Thursday, January 27, 2005

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LET'S GET READY TO RUUMMMMBBBLLLEE!

Thank you for all your comments and questions today, and welcome to new readers in West Virginia and North Carolina. I first want to put out my statements on the storms this coming weekend and early next week. Then I will go back later this evening and revisit your questions and do a "picture show" post where I will provide straight-forward answers based on the science behind the storm. Between now and then is dinner with my wife, and then we will do storm preparations. Hint.

1. BASIC FORECAST FOR NEXT SERIES OF STORMS

1-27 Update: The next 4 to 6 days will feature a highly complex and widespread series of storms for the Eastern two-thirds of the United States. Four separate but inter-connected storm systems will affect the Great Plains, Ohio Valley, Southeast, Northeast and New England from Friday well into Wednesday.


A large, very cold high pressure system will dominate most of the East Coast from New England to Georgia well into Sunday. A large, slow-moving, moisture-laden Low pressure system has developed on the fringe of this high in the southern Rockies (Storm 1) There is a second system now developing in Arizona (Storm 2). Each of the two Storms (1 and 2) will spawn a secondary Low along the East Coast in different locations, thus the end result will be four distinct storm systems.

If you were hoping for a simple solution, then all I can say is that it will probably snow, sleet and ice where you live if that's anywhere north or east of Atlanta between Friday night and Wednesday morning. But this is an extremely complex storm that has thrown the computer models into a conundrum. I have tried to break it down as succinctly as I can.

STORM 1 will move across the Southern Plains and into Tennessee Valley toward the Mid-Atlantic by Saturday. By early Sunday morning, the primary Low pressure (Low 1A) will reach West Virginia. By Sunday morning, the first high is sinking south and east, and a new Arctic high moving southeast from Canada will send a reinforcing surge of cold air into the Northeast.

Low 1A will affect Northern Georgia, interior South and North Carolina, eastern Tennessee and Virginia with significant icing of up to 1/2 inch as well as heavy wet snow. Concurrently, a secondary Low pressure (Low 1B) will develop along the Carolina coast, move northeast and draw in considerable moisture from the Atlantic. The second Arctic high will provide a fresh supply of cold air to allow Low 1B to become a significant coastal storm, producing snow, sleet, freezing rain and some rain affecting the I-95 corridor from Washington north to the metropolitan areas of Philadelphia. Other regions to be significantly impacted by this storm include interior North and South Carolina, the Shenandoah Valley of Virginia, southcentral Pennsylvania, coastal New Jersey and parts of Long Island.

STORM 2 will follow the heels of Storm 1, with a Primary Low pressure (Low 2A) taking more southerly track, and reaching the Tennessee/NC border by Monday afternoon. A secondary Low pressure (Low 2B) will also develop near the North Carolina/Virginia coast, deepen rapidly, and head north-northeast by Tuesday morning. This system will move slower due to a blocking Arctic high pressure system which will fill in behind the wake of Storm 1.

Both events will bring a long duration of winter precipitation over a period of several days, and may become very significant storms for the I-95 corridor from Atlanta to Boston.




2. REGIONAL FORECAST: STORM ONE (Saturday to Monday morning)

North Georgia to Carolinas: Snow, sleet and freezing rain in mountains on Saturday late afternoon into the evening, and light rain changing to snow and sleet in northern Atlanta. Interior western SC and NC will see freezing rain and sleet, causing possible power outages depending on amount of ice. Snow amounts of 2 or more inches are likely, with ice accumulating from 1/16 to 1/8 inch. Interior and western Carolinas will see ice amounts of up to 1/4" This will become a major, near-crippling ice storm for this region.

Virginia-West Virginia: Low 1A will produce interior mountain snows accumulating 6 or more inches begins Sunday early morning. Snow also begins early Sunday morning in the piedmont and coastal plain, changing to sleet, freezing rain, and rain along the immediate coast as the daytime warming occurs. Areas impacted include Charlottesville northwest to Harrisonburg, and then southwest beyond Lynchburg and Roanoke. Richmond will see snow change to sleet and then rain.

Maryland and Del-Mar-Val: Low 1A will produce interior mountain snows in western Maryland, accumulating 6 or more inches. Metropolitan DC and Baltimore northeastward to the PA line will see snow begin around midnight Saturday, moving from south to north, and accumulate 2-4 inches by evening Sunday. A mix with and changeover to with sleet and freezing rain overnight Sunday is possible. A changeover to all rain along Del-Mar-Va coastline is likely until Low 1B begins to pull down colder air from Canada.

Pennsylvania: Low 1A will produce some interior snows near and just north of the Pennsylvania border, but any heavy accumulations should stay south of I-76. Overall, accumulations of snow and ice will be higher farther south and lesser to the north. A changeover to sleet, freezing rain, and rain is possible on the WEST side of the Appalachians, due to cold air in place on east side of mountains. Snow totals from Low 1A in southcentral PA are 2-4 inches by Sunday late morning, before a brief changeover to sleet and freezing rain.

Metro Philadelphia will be impacted by Low 1B of Sunday night-Monday, where heavy wet snow will develop from southeast to northwest, overspreading the area by midnight Sunday. Accumulations will be generally 3 to 6 inches of wet snow, with some locally higher amounts in the far western suburbs.

New Jersey-New York City-Long Island: Some impact from Low 1B, as the developing coastal system pulls away. Main impact will be felt from Storm 2A and 2B. Coastal Low 1B begins to rapidly develop Monday morning along Virginia/Carolina coast. Some fringe snows will reach NJ and NYC, but accumulations will be less then 2”. By late Monday afternoon, wet snow will spread across coastal regions of Long Island and New Jersey, ending by midnight Monday. I still think this region has the potential to get hammered by Low 1B.

Southern and Southeastern New England: The track of the secondary Low 1B is expected to go northeasterly, thus precipitation is likely to avoid most of New England except for extreme southern areas such as Martha’s Vineyard. The main impact to this area will be the Storm 2’s primary and secondary lows, which will not reach this region until Tuesday. A Canadian high filling in the wake of Low 1B will deliver fresh Arctic air to the region, allowing almost all the precipitation from Storm 2A and 2B to be snow.

STORMS 1A & 1B: SUMMARY OF SNOW and ICE PROJECTIONS

Interior and mountainous regions of Southeast/Mid-Atlantic: 4-6 inches

Metropolitan and Interior areas of Central and North, Georgia, N and S Carolina:
2 or more inches of snow, followed by 1/8 to 1/4 inch ice

Metropolitan areas of MD/Northern VA/SE Pennsylvania: 2-4 inches

New Jersey/New York City: 1-2 inches

Southern/Southeastern New England: light accumulations (Storm 1 only)

STORM 2: EARLY PROJECTIONS FOR SNOW and ICE

While the precise dynamics of this second system are still being analyzed, it is becoming more apparent that cold high pressure will be in place as Primary Low 2A and Secondary Low 2B arrive on the East Coast Monday. It is possible that extremely significant snows will result over a very large portion of the Coast from the Carolinas northward to New England. A persistent snowpack over most areas from the Mason-Dixon Line on north will insure lower-than-expected daytime and overnight temperatures, thus snow ratios in Storm 2 will be much higher. I cannot give estimates as this time, but suffice to say that the “Storm C” description outlined in a post earlier this week would be the basic idea for Storm 2. That one is likely to be the major east coast blizzard type event I have been alluding to all week, and Storm 1 is just the front-runner.

2. ANALYSIS OF FORECAST

I have reviewed the latest NWS forecast discussions along the East Coast this evening. You can too, just click on the name of the city under "Forecast Discussions" and scroll down to where they start talking about "Long Term." Here is an example from the DC-Baltimore office which is alluding to my version of the storm evolution. First paragraph is this morning, second paragraph is this evening.

MORNING 1-27: GFS AND ECMWF BOTH TRACK THE SFC LOW TO THE SOUTH OF THE REGION FROM THE LOWER TN VALLEY...ACROSS THE VA/NC BORDER AND THEN NORTHEAST ALONG THE EAST COAST. THIS TRACK COULD PRODUCE SNOW...BUT WELL TOO EARLY AND WILL STAY WITH CURRENT FORECAST OF RAIN/SNOW MIX.
EVENING 1-27: GFS SUFFERING FROM LESS THAN DESIRABLE CONSISTENCY. GIVEN MDL DIFFICULTIES IN INTERPRETING A CMPLX PTTN...HV STAYED CLOSER TO AN ENSEMBLE/PERSISTENCE FCST... STICKING TO A CPL OF PRINCIPLES. THESE ARE... 1/ PTYPE SHUD START AS MAINLY SNW...SINCE THERE WL BE A DRY AMS TO EVAP MSTR INTO... 2/ WAA WL YIELD AT LEAST SOME MIXED PCPN...AND THE MIX WL BE GREATER IN SRN/SERN SXNS. UNSURE ABT QPF AMT...NOT TO MNTN PTYPE. A GENERIC SPS WIBIS TO HIGHLIGHT A POTENTIAL WEATHER EVENT. ALSO...HV UNDERCUT MAXT TO BE MORE IN LINE W/ MIXED OR FRZN PCPN.


I can tell you that I believe the fingerprints on the smoking gun is the current trend of the NAO. Read Tuesday's post about the North Atlantic Oscillation. It is a statistical improbability that a storm will go up west of the mountains during a negative NAO, or turn to all rain along the East Coast. Just ain't gonna. As a result, you will see NWS forecasts start to trend colder and more snowier with time, as they pick up on this trend, which as of this evening, it appears they are starting.

Here's snippet from the Boston NWS Office: (I expanded their abbreviations)

"Storms, model ensembles and operational runs from the gfs/ecwmf and ggem all support several coastal events somewhere from the Carolinas to New England next week and beyond. Long term, later..low pres/snow risk Sunday should be for the snow starved region of the Mid Atlantic south of the Mason Dixon line while a secondary cold front gets stuck here in SE New England awaiting further and more important mid Atlc coast developments for Tue/Wed as now agreed by ecmwf/gfs operational runs."


And the Raleigh-Durham, North Carolina NWS Office is beginning to see the colder trends I have been talking about... (caution, this is long. The caps are their doing, not mine. Trust me, they are not shouting at you.)

WHAT LOOKED LIKE MORE OF A QUICK NUISANCE ICING EVENT YESTERDAY NOW LOOKS A LITTLE MORE DIRE. THE 00Z/27 GFS CAME IN DRASTICALLY DIFFERENT FROM ITS PREVIOUS RUN... AND CLOSER TO THE FORBODING ECMWF... WITH ITS DEPICTION OF A COASTAL CYCLONE DEVELOPING OFF THE SE COAST SAT NIGHT... EXITING SUN NIGHT... AND FOLLOWED BY ANOTHER LOW APPROACHING FROM THE WSW LATE MON. THE MID LEVEL WAVE THAT THE GFS BRINGS ACROSS THE OH VALLEY/MIDATLANTIC LATE SAT THROUGH SUN IS A NEW FEATURE WITH THIS RUN & LOOKS TOO STRONG SO HAVE IGNORED ITS ASSOCIATED QPF BULLSEYE...

And here's Philadelphia recognizing how the GFS has led us astray with it's "BIG WARMUP"

1-27 MORNING: THE GFS HAS TRENDED COLDER DURING THE BEGINNING OF NEXT WEEK...WHICH BRINGS IT MORE INTO LINE WITH THE OTHER MODEL GUIDANCE. THE GFS HAS BEEN THE OUTLIER...WITH ITS WARMTH... FOR THE PAST FEW DAYS. HOWEVER...IT CONTINUES TO BE THE MOST ROBUST WITH THE MOISTURE AND ENERGY APPROACHING THE REGION TUESDAY AND WEDNESDAY.

1-27 EVENING: THE HIGH OVER THE AREA GRADUALLY PUSHES AWAY AS LOW PRESSURE TRIES TO MOVE UP FROM THE SOUTH. HOWEVER, IT APPEARS ON THIS LATEST 12Z RUN THAT THE HIGH MAY BE STRONG ENOUGH TO KEEP EVEN ANY SMALL EFFECTS IN THE SOUTHERN HALF OF THE AREA SUNDAY INTO SUNDAY NIGHT. ANOTHER SURFACE WAVE APPEARS TO WORK SOUTH AND EAST OF US EARLY NEXT WEEK, BUT THE ASSOCIATED UPPER TROUGH COULD PLAY A ROLE IN GENERATING MIXED PRECIPITATION (DEPENDING ON LOW LEVEL TEMPERATURES) INTO TUESDAY NIGHT. CONFIDENCE AT THIS POINT IS LOW, BUT IT DOES NOT APPEAR TO BE A STRONG STORM FOR US WITH A LACK OF PHASING BETWEEN LOWER AND UPPER LEVELS OF THE ATMOSPHERE.


We'll see about that last part.. no phasing of the streams? We shall indeed see what happens.

3. PHILOSOPHY BEHIND THE FORECAST

I developed the storm descriptions you read above yesterday, then revised them today around 1:00 PM during my lunch break, before the newest run of models came out, and before the NWS started hoisting the storm flag. Then I noticed afterwards that Accuweather started trending colder in their forecasts, as has the NWS in Baltimore, Philly and Boston.

I am not going to flop around each time the models change. That's why you see a different, bewildering forecast on the Weather Channel every 6 or so hours. I think some offices at the NWS are once again blindly following the GFS, while others are recognizing it's demonstrated weaknesses thus far this winter, and are not giving it a lot of credence right now. There is huge disparity in the modeling for this storm, but the one constant that IS GOING TO RECTIFY ALL FORECASTS toward a snowier stormier solution is the negative NAO. It cannot be denied.

This is an extremely complex situation that we have not seen in a long time. These 2 storms will probably be harder to predict than the February 2003 Blizzard, and the complexities will lead to even more variance in the forecasting as we get closer. Be prepared to see almost every time of solution imaginable even up to 12 hours before the event, some will say all rain, others will say all snow, and most everyone else in between.

If I end up being way out in left field, and it rains all over the place for three solid days starting Sunday, and Boston washes down into the harbour, then I will gladly explain why my forecast went wrong and what lessons can be learned from it. I do notice how TV forecasters are hedging quite a bit and trying to resolve how the colder air redelivery will impact the secondary Low. I just don't think you can have a large moist Low heading through the Ohio Valley, given this pattern, and NOT have a secondary develop off the coast, pull in colder air, and bomb out on it's way to New England. I think you ignore that possibility at your own peril.

I believe the TWO primary storms have the potential to surprise a lot of people with higher than expected amounts of snow, ice and wind...given that they each will spawn a secondary. And... this has been said before...THE STORMS ARE GOING TO COME FARTHER NORTH THAN EXPECTED. There is a rain element in both storms, but not a total washout, and confined to a few hours of daylight in the north, or in right along the coastline south of Philadelphia.

These events are the beginning of an extended period of record-setting period of storminess, snow and cold for the Mid-Atlantic, Northeast and New England. I said earlier this week that there would be at least 3 major storms for the Northeast over a short period of time, each storm getting progressively worse, more intense, and snowier. Now it looks like that number should be 4. Accuweather has alluded to this in a graphic this morning. The next major event looks to occur next weekend, and it could be...well, extremely significant. Yeah, I know you hate that word. It is so overused these days. So I'll just say it. Translate significant into SNOWSTORM. Florida got 3 hurricanes in a 30-40 day period, why not 3 blizzards/major storms.

Tonight or tomorrow, I'm going to get a LARGE RED gas can to be my main supply, from which I can create the oil-gas mix for my snowblower, just in case I am unable to go anywhere for a couple days. Or in case I have to plow out 6 inches of heavy wet snow. Bostonians... recommend you clear off your roofs soon, so you are ready for anything.

CONSIDER SOME WHAT IF’S…WHY I THINK FORECASTERS ARE HEDGING

WHAT IF…The high currently in place stays longer or ends up being stronger than forecast. Weekend temps will end up being lower than we expect, and thus temps at onset of the storm are several degrees below what is currently forecasted.

WHAT IF the high moves a bit southeast instead of due south as GFS is predicting. This will capture more of the Northeast under the cold dome well into Sunday.

WHAT IF the second High coming in Monday simply links up with the first high. This would give rise to a situation where we thought we’d have “retreating cold air” as Accuweather has stated, and instead we have “firmly entrenched” cold air into which all this Pacific, Gulf and Atlantic moisture is driven.

WHAT IF
the Storm 1 moves in quicker than anticipated, and the high moves out slower. Then you have precipitation arriving during the overnight hours either Saturday night or early Sunday morning. Overnight precip is going to be mostly snow, and evaporative cooling will lower the atmospheric temperature a few degrees, eliminating any changeover to rain on Sunday. The Baltimore NWS finally recognized this potential and went with a Special Weather Statement today. It’s all about the Negative NAO. Accu-weather forecasters follow this mantra… “If you predict the High, then you’ll predict the storm.”

And that’s what I’ve been focusing on… where will the High be and how strong once it is there. If you've read all the way to this point, CONGRATULATIONS. You are a true blue (white) Powderhound. Again, I will review your questions this evening and post a response later tonight with some pictures to back up the answers.

Regardless of what happens, it will be an exciting weekend.


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BEHIND SOME GOOD MEN IS A BETTER WOMAN
6:00 am Thu - UPDATES TO "ANALYSIS" SECTION TOWARD BOTTOM OF POST

Now this is not to imply that single men cannot be good, many of them are. I just feel fortunate and blessed to have such a great woman by my side, who is also a great Mommy to our 18 month old Jayla. Mrs. Foot has given me a lot of freedom the past week to do what needs to be done with this site to make it better for our readers. We love our daughter to pieces, but is has been nice this week while she is visiting Grammy so Mommy and Daddy can get quarter grades done...and I can analyze ad infinitum on the next storm.

Many of you will also be thankful for Mrs. Foot, because she read the site today for the first time in a while…. AND COULDN’T FIND THE FORECAST!! This is a problem. I am embarrassed. If my own wife has trouble finding the weather on the site, then changes are needed. Fast. So we went for a walk, and talked (about other things too, not just the weather) and she recommended some modifications that will make it easier for you (and her) to find what you are looking for. I
t is neat that this new format would come into play on the ONE YEAR ANNIVERSARY to the date this site has been online. That's right, the first broadcast was January 26, 2004. What a year in weather is has been, and will continue to be.

SO HERE IS THE NEW FOOT'S FORECAST FORMAT. It has three simple parts.

1. The straight weather forecast (whatever the hot topic is… a snowstorm, hurricane, etc.) The basic nuts-and-bolts forecast will be issued first for the area under threat of bad weather. No computer model mumbo jumbo, no NAO this and PNA that. Just the weather.

2. The scientific analysis. If you are skeptical of the forecast, have told your friends to start buying snowblowers, or want the scientific basis behind my call, read on to this section. If you are satisfied with the call made in section 1, you can skip section 2 and 3.

3. The philosophy. You understand the weather and the science, but are hungry for more and want the full picture with all it's complicated half-witted analogies and more. Then read on past the analysis to the philosophical background of the forecast.

DISCLAIMER: During megastorm mode, I cannot guarantee this will always be followed, as fatigue, frustration and excessive blogging late at night in advance of major storms may lead to a mangled merger of the 3 sections above, but I will do my best. I strive to put the best safety interests of my readers ahead of weather lingo and ego.

BEFORE WE GO ON TO THE WEATHER… Grading January 22-23 snowstorm/blizzard # 1

Baltimore to PA/MD line: Forecast 8-12 Actual 6-7 Score 6/8 = 75% C

Dundalk, MD (my home): Forecast 8-12 Actual 5 Score 5/8 = 62% D

Southern PA (York Cty.) Forecast 8-12 Actual 6 Score 6/8 = 75% C

Western PA ( 7 Springs) Forecast 12-18 Actual 10 Score 10/12 = 84% B

Philadelphia (airport) Forecast 12-15 Actual 12.6 Score 12.6/12 =105% A*

New York City (JFK) Forecast 10-14 Actual 11.5 Score 11.5/10= 115% B

Boston (Logan) Forecast (initial 6-8” by Sunday night, final call was 30” total)
Actual 22.5 Score 22.5/30 = 75% C

Washington (Dulles) Forecast 4-6” Actual 6” Score 6/4 = 150% E

Overall storm forecast GPA: 2.12 Grade C
If you discover an error in my number, either the forecast amount or actual, let me know.
Explanation of snowfall grading scheme:
All future storms (including today’s micro-blizzard in Mass.) are graded on a single number issued for a specific location where an accurate observation can be verified, such as an airport, or a general trend as reported by colleagues.

I will give a range of expected snowfall, but at the final forecast before the storm begins, the grade is based on the single accumulation number which I will announce. For Boston, I originally called for 4” and should have stuck with that, but revised it to 9” for Logan International based on higher QPF. For the region surrounding the graded location, it is assumed there will be a variance of 2” on either side of the number, but the grade is on that number.

So the Boston area grade is: 5.6 inches reported at Logan as of 1:00 AM Thu / 9" predicted= 62% and that’s an D. So at least I passed. Because despite the higher QPF, the heavier snow portion of te storm moved out quicker, and the real bomb-out did not occur until the Low had moved well-offshore. Some light wraparound snows added another inch overnight.

Wednesday, January 26, 2005

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LET'S DO THE TIMEWARP AGAIN...
-Rocky Horror Picture Show

SIGNIFICANT WINTER STORM TO DROP ANOTHER 6 TO 10 INCHES ON EASTERN MASSACHUSETTS TODAY. Boston to easily break it's all time snowiest January. For my powderhounds, it is pure heaven. For powderhaters, it must be a horror show.
Official Foot's Forecast for Logan International... 9 inches.
Based on daytime temp of 25 F, which is a ratio of 15:1 or so and a QPF of .60.
New site updates include excellent US loops of the ETA, GFS, NGM and UKMET. Enjoy! This should help us all stay on top of the next big storm.
I'm not the only one concerned about a potential storm. Accuweather has some graphics illustrating their initial predictions on this late weekend threat. Models are misbehaving so I will take a closer look at the situation tonight.

Tuesday, January 25, 2005

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TWO ROADS DIVERGED IN A YELLOW WOOD... AND I TOOK
THE ONE LESS TRAVELED BY, AND THAT HAS MADE ALL
THE DIFFERENCE.

- Robert Frost, from "Stopping By A Woods On A Snowy Evening."

WARNING: Ultra long post. It has to be that way because I must lay the groundwork for the basis of this storm forecast. But if you don't care about the philosophy or the science, and just want the straight talk, then just scroll to the end, I won’t be offended.

The picture above was taken at Seven Springs this past Saturday afternoon as I was skiing in beautiful fresh powder. Looking at this picture, I think to myself… here is a vast field of trees, with many different trails to take. All those trails at first lead to a variety of places, but as I continue along any particular trail, after a while, I reach two possibilities. One, the wrong trail leading me out of bounds and into thick woods. Or…Two, having skied these trails several times before, I have a fairly good sense about which one to take that will eventually connect with others, and ultimately take me to the bottom of the mountain, and my final destination.

But before I overwhelm you with intense scientific analysis, please consider my second analogy.

Earth’s climate and weather all follow a regular pattern. The pattern may not seem very discernible to us mere mortals at times, especially when it is in cycles of 60 or 120 day or 10 years or 200 years. But each weather pattern is an on going highly complex chemical formula, that continually repeats and resolves itself. Recognizing the pattern is more than just looking at the cover of the Da Vinci Code, and saying… “there’s that book!” and then reading the inside flap. To get a real sense of what author was trying to convey in cracking the “Code” you have to immerse yourself in the intricacies of the book and try to pull out some meaning that you and others can understand. Then, when someone asks you, “What’s that book about?” You can give them a reasonable explanation based on your understanding. Usually, when a lot of people read the same book, there are different opinions as to the meaning, but most everyone will come up with some kind of synopsis that is close to the main ideas. Rarely would you have someone give you a synopsis of a book that is totally out of synch with what everyone else read, or you would probably say… “Were you reading the same book that I did?”

And that’s what we have going on with our next big storm. Everyone is reading the same book (the forecast models), and most of the readers (forecasters), are coming up with pretty much the same synopsis of what the book is about (the weekend forecast). Everyone else around them has said, “Since you read the book already, I’ll just take your word for it, and not bother reading, saves me time. Besides, your analysis seems to fit with what everyone else is saying.” But you have read my synopsis of the book, and are thinking, "How is he coming up with that?"

Now relate these two analogies together, so you understand where I am going with this. I have skied for 15 or more years now, and visited a good number of resorts. I have gained an intuition about how trail network is laid out, that I can find my way back to the base lodge easily enough without getting lost. I can just take the standard trails I see everyone else skiing down, and that’ll get me back quickly, little effort. But part of the thrill of skiing is finding those interesting and little known trails, which are clearly marked on the map, but not as well traveled. Such as the picture above… glades, among my favorite type of trail. So I venture through the glades, and I think… “Gosh, this is so pretty here, I wonder why more people don’t come this way?”

And then it hits me… first, I don’t want them to come this way, because too many will spoil the pristine atmosphere at the moment. Second, they aren’t going to come this way regardless, because it looks too different and unfamiliar. It is “off the beaten path” maybe too dangerous, maybe too risky, not sure where it leads, how would I ever get back? That picture was middle of the day, and it appears that not too many people had gone that way since morning. But I took the one less traveled by, and that made all the difference, because I inadvertently found a new route back to the base lodge, one that no one else had skied yet, because it was all fresh powder underneath.

And that my friends, is what I also plan to do with this forecast. I will take the trail less traveled by, because I believe I have enough scientific basis on my side this time, and the confidence to veer away from the traditional routes. My hope is to explain to you the new trail I am taking in a way you'll understand, before everyone else finds it.

ANALYSIS FOR SECOND EAST COAST STORM LATE THIS WEEKEND

Now that you’ve survived the philosophy missive, let’s get on to the real deal.

PART I, TAKE A HAMMER TO THE GFS

(This is the NOAA’s flagship computer model, the Global Forecast System. While is an excellent tool, it is replete with significant errors which have led to debacle after debacle in the big storm arena.)

1. Frustration over wildly vacillating Accuweather 15-day forecasts is a waste of our valuable time because most of those forecasts are tied directly to the GFS database. I’m sure it’ll keep printing out 50 degrees for Boston until the day before the storm.

2. The GFS was the same computer model which consistently predicted that Hurricane Jeanne would GO OUT TO SEA and never hit Florida, let alone in the same place that Frances did. You what really happened.

3. In February 2003, the GFS was unable to initialize in it’s data runs the fact that a gargantuan Arctic high was going to park itself over the East Coast and block forward motion of an intensely moisture laden system coming out of the southwest and Gulf of Mexico. I saved the last Special Weather Statement issued by the Baltimore Washington NWS Office, before I left for the weekend and go to…. Where else? Seven Springs. Would you believe the NWS was still expecting a mix with and changeover to sleet and freezing rain in THAT storm? On Friday, 2/15…forecast highs were in the low 30’s for Sunday at Baltimore. The actual high? 18 F. What was going to be several inches of wet snow at my house (as indicated by the weather service ended up as 23.5 inches, and the rest you all experienced yourselves.

4. How quickly we forget. The GFS was the LAST model to come on board with Blizzard #1, as E.H. in Boston pointed out, and even then just 12 hours before onset of precip. And you’ll remember that’s when most of the NWS offices went berzerk with their Day After Tomorrow-type snowfall predictions. The GFS was consistently advertising that Blizzard #1 would head southeast and out to sea, not to affect New England at all. Did I not say that when we think it will not be as bad, it ends up being much worse than we expect.

5. The GFS has also consistently underestimated the strength of high pressure systems coming southeast from Canada. This is why you have seen forecasted daytime highs and overnight lows for Thursday and Friday dropping all week long for the East Coast. All those 3 and 5 day outlooks? Print them out, put them on your fridge, and keep checking your thermometer to see how accurate they end up being. In fact, Friday morning may be the COLDEST it has been all winter from DC to Maine and everywhere in between. All that cold air is going to filter down the east side of the Appalachians.. all the way to the Carolinas. With a stagnant Arctic air mass dominating the entire Northeast, what scientific basis is there for all that low-level cold air to be suddenly scoured out by Sunday?

These are only a few qualitative example of how this computer model has consistently underperformed it's peers. So why would the NWS continue to follow it, seemingly blindly at times? Politics and power. It would be treason to base a National or Regional forecast solely from a foreign computer modeling program? You don't think certain NWS offices get indirect pressure to lean more favorably on the U.S. model? Then think again about office politics.

PART II : UNDENIABLE EVIDENCE OUR BIG STORM IS COMING

There are several factors crucial in determining whether a big East coastal low will become an all-out-blizzard, a pesky ice storm, or an annoying cold rainstorm. They are…

1. The North Atlantic Oscillation
2. The Arctic Oscillation
3. The Pacific North American Teleconnection
4. Water temperature anomalies off the East Coast

I don’t include the jet streams in that list because the three major upper air phenomena are what drive changes in the jet streams in the first place.

So get a cup of herbal tea, I hear it helps you think clearer, because this is going to be heavy science. But it is worth the read. If you can understand this, then’ll you have also have a clearer picture on where my seemingly out in left field forecasts come from.

1. The North Atlantic Oscillation (The NAO)

What is the NAO? (These are excerpts from a NOAA site I found, and condensed it down for the site.) The North Atlantic Oscillation is defined by differences in pressure between the persistent low over Greenland and Iceland (the Icelandic Low) and the persistent high off the coast of Portugal (the Azores High) During a positive NAO, both systems are stronger than usual. That is, the low has a lower atmospheric pressure and the high has a higher atmospheric pressure. During the negative phase of the NAO, both systems are weaker, lowering the difference in pressure between them. (end of NOAA summary, found here)

You know that a tight isobar gradient indicates strong winds, as the pressure difference between the high and low are very large, thus intense storms often wind up and become these highly compact systems. A high pressure system, by contrast, is a large, expansive dome of air. When the NAO goes negative, it means that the Icelandic Low and the Azores High both become larger and more spread out, as the pressure differences between them are not as much. This in turn allows for the Icelandic Low, which is naturally much more closer to the North American coast, to influence the weather of that coast. This diagram shows what happens in a negative NAO.. as the Icelandic low, with it’s counter-clockwise rotation, moves closer to the U.S. East Coast. By doing this, it begins to cause what forecasting term “blocking” in that it interferes with the normal jet stream induced flow of storms, as well as re-direct the movement of Arctic highs coming down from Canada. The highs get shunted into the Northeast U.S., and any southern stream storms coming out of the Gulf of Mexico, usually loaded with moisture, get funneled into the path of those Arctic highs.

The Negative NAO signal. Look at the
current NAO chart yourself. Look what happened right around the 23rd…. the NAO flipped from strongly positive to mildly negative. NWS forecasters do know about this stuff, it’s their data. Perhaps they forgot to check it, I don’t know. But I can tell you there is a very strong correlation between changes in the NAO and the occurrence of big storms along the East Coast. Boston… when was your last storm since November? Look at the NAO chart. Does that verify? Notice how the positive NAO in December corresponds to the much-above normal temperatures we all experienced throughout the Northeast last month? Then look at January. Started out warm, and the NAO just kept dropping and dropping as the month progressed, eventually flipping to negative just last weekend. What followed immediately after the flip? A little Alberta clipper that kept growing until it became one of the top 5 biggest storms in New England history. Knowing what you do now about the NAO, don't listen to any forecaster who blames the bad calls on the fact that the storm just "came out of the blue. " Nonsense, their homework went into the blue.

Where is the NAO headed? It is already trending STRONGLY negative and forecasted to continue that over the next two weeks. View for yourself NOAA’s 7, 10 and 14 day projections. I think local NWS offices are for some reason discounting that the NAO signal is already significantly OFF the forecasted value. Look very closely at the second chart, see that black line? That is the current NAO "value" based on observations. Notice how far off that line is from the forecast for where it is supposed to be. It may not look like a big difference to you, but in forecasting lore, the value was supposed to be about a .75 deviation to positive. Instead, as of today, it is over 1.5 deviations to NEGATIVE. That's the equivalent of forecasting 7 inches of snow, and the result is 22 instead! Does that sound familiar, Boston?

Now, look at the second, third and fourth charts... what is the overall trend for the short term to about January 27? Is NAO forecasted to be... negative, neutral or positive?

The correct answer is...FORECASTED TO BE POSITIVE for the immediate term. That forecast was made a week or so ago.

THIS IS WHY YOU SEE A "WARMUP" IN YOUR WEEKEND FORECASTS. The GFS INITIALIZES THE NAO FORECAST IN IT'S DATA RUNS, BUT SOMEHOW SEEMS TO DISCOUNT THE NAO OBSERVATIONS. Please forgive the caps, I am not shouting, just trying to strongly emphasize that we have found the smoking gun, have we not? The bias toward a positive NAO is in direct contradiction to current observations, so the NWS offices have to manually adjust their temperature projection because the GFS has an above-normal temperature bias because of the positive NAO signal.

What will probably happen is once enough observational data comes through between now and Friday, the GFS will start to change it's tune, and back off the warm trend. Then slowly, you'll notice the NWS forecasts start to ever so slightly trend colder, first temps will nudge down a degree, then the precip type will begin to shift toward a more snowy solution. And finally forecast discussions will begin reflecting this in the next few days.

I will discuss these three factors in more detail with Wednesday evening's post.

2. The Arctic Oscillation

3. The Pacific North American Teleconnection

4. Water temperature anomalies off the East Coast

PART III: THREE STORM SCENARIOS

This is the three most likely situations that will occur late in the weekend to early next week, as some computer models have slowed the potential system down quite a bit.

Storm A...All washes away. The cold air this weekend is quickly replaced by warm air advection from southwest flow of the moderating high pressure. A storm does form in the east side wrinkles of this high, but cuts up through the Chesapeake and into the St. Lawrence River Valley by Sunday night, bringing widespread moderate to heavy rain and the potential for significant flooding in snowpack areas of New England and the Northeast. Mr. Foot wears a big grocery bag on his head and posts a picture on the website for all to see.

Storm B...Big trees falling down everywhere. The cold air this weekend remains firmly in place, filtering all the way to South Carolina. A low pressure in the Gulf moves off the Carolina coast, and over-running moisture falls through the surface layer cold dome. With 2-3 inches of liquid available, this becomes a major to nearly catastrophic ice storm for the Carolinas and Southeast Virginia. The Northeast is spared any serious impacts other than a few inches of wet, sloppy snow and some tail end freezing rain as the storm departs east. Mr. Foot wears half a grocery bag.

Storm C...Can you dig it? (even if there's 2 more feet of it?). An unusual confluence of events results in a strongly Negative NAO signal which correlates with the arrival of an large Arctic high into New England on Thursday. The high moves south and expands, temperatures are notably colder than originally forecasted. At the same time, an active southern jet stream sends a developing low pressure system through the southern Ohio Valley, which eventually redevelops off the Carolina coast. The high drifts off the coast, and becomes entrenched due to it's proximity to the Icelandic Low. The resulting blocking of the storm's movement enables the low and high in conjuction to tap warm Atlantic waters, feeding tremendous moisture into the cold dome of air over the Northeast for 2 or more days. The result is a historic paralyzing blizzard with snowfall amounts of 12 to 24 inches for all major cities from Washington to Boston, and 24 to 36 inches in interior sections of Pennsylvania, Maryland, New York and New England.

Mr. Foot mails a grocery bag to every NWS office on the East Coast with his web address printed on the side.

Only time will tell what really happens, but by Thursday we should have a better sense of which scenario is likely to play out. Of course, you know I am still leaning on Storm C.

Brief update tomorrow morning, followed by fine tuning of the three scenarios tomorrow night and continuation of Part II.


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THREE HURRICANES IN ONE MONTH
WHY NOT THREE BLIZZARDS?

Second of three major winter storms to grip East Coast late this weekend from South Carolina to New England...each storm will be more intense and widespread than it's predecessor. National Weather Service beginning to recognize atmospheric parallels to previous patterns which have led to crippling, immobilizing storms in the past. Accuweather already hinting at possible major storm, but computer models are all over the place as usual.


HOUSE-KEEPING AND SITE UPDATES

- I have added a variety of new links in this "calm before the storm" to help you understand the science behind the forecasts, if you wish.

- I have yet to complete the wrapup of Blizzard #1, and my new grading scheme. I will post that tomorrow along with my grades for snowfall totals across the Northeast. The overall storm forecast was a B- and I'll explain how I arrived at that so you can see it is fair statistical formula.

- Before I go back into giant megastorm mode, I thought it appropriate to re-introduce myself a little more to new viewers and discuss my background with weather so you know where I am coming from.

WINTER STORM WATCH FOR SOUTHEASTERN NEW ENGLAND TONIGHT

Another vigorous clipper (according to ABC 2 in Balto, is clipper #5 as of late) will swing through Pennsylvania today, bringing a light snow/light mix to the southern portions of I-95 from Philly on south. Central PA might pickup a couple quick inches due to lake effect, as will mountains of western PA near Seven Springs Resort. Reaching the Jersey coast, all eyes are on New England as it is believed this system may slow down some (have we learned our lesson?) and tap that readily available above normal Atlantic water. Thus a general swath of 1-4" looks likely from central and northern PA to north of NYC and into SE new England. Then late tonight as Atlantic moisture is tapped, some regeneration of the Low enhancement is expected along the coast, with a wraparound that can drop up to 4 inches in Boston and 6 inches along the Cape by early tomorrow morning.

For a few hours, it may look like Blizzard #1 was making a comeback, just like the quick bursts of snow we all saw Monday afternoon.

GRADING SNOWFALL FORECASTS. Please note in my new snowfall projections that I am now issuing a SINGLE number. The expectation is that the results will be 2 inches on either side of that number. So if I predict 4 inches for Logan Airport, and 3 inches fall, the score is a 75% and the grade a C. If the storm goes berzerkoid, and Boston gets 6 inches, that is 125% but still 25% off, so the grade is still a C.

ANALYSIS OF BLIZZARD # 2 FOR THIS WEEKEND

Explanation of maps above.

Panel 1, left top is the European for late Sunday night. It has changed somewhat recently, but has consistently advertised a fairly hefty system rolling up the east coast late Sunday. Notice the high PARKED IN THE WAY ahead of the storm. Same setup as notable Blizzards of the past, namely 83 and 03.

Panel 2 and 3 is the Global Sea Surface Temperature Anomalies for Jan 03 and Jan 04. Notice the extremely warm water (reds and oranges) off the Northeast Coast right now, as compared to Jan 03. Notice how the Gulf is a degree or so warmer now than it was 2 years ago at this time. This water temp variance will be critical in the next 3 weeks as it is pretty much the Quarterback of this game.

Panel 4 is the North Atlantic Oscillation, a measure of changes in atmospheric mass/air pressure between the Icelandic Low and the Azores High. When the "NAO" flips negative, the East Coast is more often than not, hammered with a big storm. WHEN THE NAO STAYS NEGATIVE FOR A LONG PERIOD OF 10 DAYS TO 2 WEEKS (as NOAA is forecasting it to do), then the East Coast is in for a period of successive storms and very cold weather.

So here's what to do this week...

1. IGNORE THE GFS (Global Forecast System). It has a history of supressing these storms too far south or sending them out to sea. How many NWS forecast offices said Blizzard #1 was not going to go north? Eh?

2. FORGET THE 'BIG WARMUP' that TV forecasters and everyone else is calling for this week. Some of the coldest air of the season is coming for Friday and Saturday. Why? Because the GFS has trouble incorporating the fresh snowpack influence on surface level temperatures. Your temps Thu-Fri-Sat will probably bust 10 degrees below what was originally forecasted on TWC and everywhere else. 50 degrees in Baltimore? Whatever. 45 in Boston? Let me know when that happens this week, cause it ain't gonna.

3. WATCH THE DANCING MODELS. No not that kind, geez. Get your mind out of the gutter. I mean how all the computer programs are going to waffle ALL OVER the place with this all week long, and it will drive all of us insane. You are going to see every forecast under the sun for this weekend all up and down the East Coast, from rain to partly cloudy to heavy snow to freezing rain and sleet to nothing. Then suddenly on Friday, presto! Major snowstorm and Special Weather Statements galore. You just watch what happens, we'll see how it ends up.

4. ACCUMULATION MANIA. I believe this storm will be a cross between Jan 22, 1987 and Feb 11, 1983. If you notice the QPF's for Day 4-5 on the links above, you'll see that what ever is coming out of the Gulf will be LOADED FOR BEAR. 3+ inches of liquid at kickoff.

Answering your comment questions

There is going to be a period of tremendous hedging by almost anyone in the forecast business about the eventual outcome of this storm. I especially enjoy watching the go-between of Justin Berk and Norm Lewis on Baltimore's ABC 2. Norm is the Chief Meteorologist on for the evening broadcasts and Justin is the early morning guy. Justin comes on Monday morning and says.. "Another coastal storm possible this weekend." Then Norm comes on Monday night and says, "Just some freezing rain, nothing big to be concerned about." Now Tuesday morning, Justin returns with a moderated "Coastal Storm Mix." Interesting to see what Norm does tonight. Once again, we have to issue a MARTY BASS alert for our Baltimore viewers, as he is going to have to make a call about this storm sometime, and it will be a tough one for him. Julee, Chip and Hereford friends, keep us posted on what Marty is up to.

So what is the reason behind everyone hedging versus me coming out with guns blazing?

NWS is hedging on this storm because they believe...

1. The cold High coming in behind this clipper is going to slide off the coast sooner than they expected, and the cold air will be retreating somewhat. That will create a southeasterly flow directing TOO MUCH warm moist air into the developing Carolina Low, resulting in more of a rain/snow/ice mix.

2. That kind of sloppy arrangement would cut down on accumulations, obviously. Coastal cities would see some snow, changing to sleet, then freezing rain and then rain.

I am not hedging on this storm because I believe...

1. Computer models are still underestimating the strength of the high coming Thursday and Friday. GFS projects that snowpack will diminish, thus moderating the high somewhat. Hey Philadelphia, you tell me by Thursday how much of that 13 inches melted away, okay?

2. This is going to be a southern stream intrusion into a cold Canadian high. Classic setup.

3. By Friday, there is another high very close by just above the lakes. Both highs will not be that much different in their pressures by Saturday. Has ANYONE considered the possibility that instead of being two distinct systems, they link and more cold air than was originally thought is able to bleed out in front of the storm? Is that a totally unreasonable idea? And if the storm develops as expected, who is to say the counter-clockwise motion is not able to tap cold air available in that second high?

4. Underestimated strength of high and lower than expected temperatures will allow for considerable cold air damming down east side of Appalachians. Many times before NWS has indicated that it is hard for the upper level warm air advection to scour out the surface level cold air. Cloud cover should be limited Saturday, allowing night time temps to plummet.

5. New England should consider themselves UNDER THE GUN because position of high on Sunday is going to slow forward motion of storm, enabling it to gather abundant moisture before the final assault. Impacts could range from a very wet, sloppy snowstorm with strong wind to a paralyzing ice storm if there is less cold air in place when moisture arrives. Imagine what would happen to all your roofs even if just several inches snow/rain/ice mix fell on top of the 18-38 inches already there? Thousands of roofs would collapse, ensuing a regional disaster. On the other hand, once the storm gets wound up with a fresh supply of cold air, what was forecasted to be several inches of wet snow becomes...1-2 feet of wind-whipped powder all over again.

SO YES VIRGINIA, ANOTHER MAJOR SNOWSTORM IS POSSIBLE AND YOU SHOULD BE READY.

Tuesday night, I will do a more specific day-by-day breakdown of how I think this will play out. In the meantime, you go get that snowblower, you'll be happy you did, and fill up about 3 of those red gas cans with the 32:1 gas oil mix. You are going to need them the rest of this winter.


Monday, January 24, 2005

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WILL LIGHTNING STRIKE THE SAME PLACE TWICE?

Don't get too comfortable in the Northeast with the idea that storm was it for us. There are rumblings in the computer models (the more RELIABLE ones) that another, more potent system may develop late next weekend. With several large extremely cold Arctic highs rolling in from eastern Canada, temperatures this week will stay well below whatever you see forecasted. The GFS especially is mis-reading the influence of snowcover, and thus local forecasters have to adjust the numbers.

What appears to be setting up is by Friday... a medium sized high parked near Montreal, with COLD AIR DAMMING down the Appalachians, and a coastal low forming along the Carolinas. I am not making this up for ratings sake. If the northwest flow continues and the upper trough shows to be tilting back toward the Great Lakes, by Saturday or Sunday we could be looking at EITHER:

- ANOTHER MAJOR STORM OF NEAR-HISTORIC POTENTIAL this weekend for the Northeast OR
- A CRIPPLING ICE STORM FOR THE CAROLINAS AND SOUTHEASTERN VIRGINIA by Sunday.

Since I am going to school today, I will not have as much time to analyze this situation, but will have the inside scoop for you by the end of the day. I also want to do a storm wrapup because there is much to discuss so you understand where I will be taking the February forecast. And I will also do a wrapup of the situation in southeastern New England.


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THE BOSTON BLIZZARD... BEYOND UNBELIEVABLE

I wanted to post a couple good pictures for all to see just how incredibly incredible the snow is up in Patriots Country right now. Beanfolk... can you help me out? Know any good links for pics I can post to show the drifts up to 5 feet, up to the 1st floor of some houses, etc? I think our powderhounds down south need to see this, because the dynamics which pummeled you can very well do a second act next month for the Mid-Atlantic.

Anyone looking for some phenomenal stats on this storm, check out the Boston Area NWS Storm Reports. 38 INCHES IN SALEM! 84 MPH WIND GUST IN THE NANTUCKET AREA. And good indepth reports from the Boston's Channel 5 WCVB

It has been quite a rollercoaster emotional weekend for all of us, especially all those Eagles/Steelers/Patriots Fans. What a combination of events, huh? Playoff mania surrounded by Blizzard mania all at the same time. I think ESPN and the Weather Channel had the highest ratings of anyone this weekend. And the digging out up there will be historic in it's own right. If the storm mayhem and playoff anticipation did not exhaust you, then the shoveling probably will! But thank you to all our newly acquired Boston readers for all the great comments. Please feel free to continue posting your obs about the recovery. I still think your schools are out the entire week.

Game prediction as of 8:50 PM... Final Score: Patriot 38, Steelers 27.

I will do a final grade for storm totals on Monday, after I turn in my quarterly grades while on duty ON TIME at my school. Chip, if the inservice day is on, I'll be reporting at 7:30 AM, I promise. Either way, I am very grateful we have this day to at least mentally recover after a wonderful but tiring ski trip. It is a total toss up what will happen tomorrow morning... some schools may delay, others will be on time, and some will close.

(12:50 AM update...a number of the surrounding school systems around Baltimore have all closed for Monday... Harford, Cecil, Anne Arundel. No word from Howard or Balto County yet. But you know the rule, as Harford County goes... so goes the region, right? I've been in Baltimore County only four years now, and in that time, I can't recall an instance where BCPS was open and Harford was closed. What do you think? Maybe the solution is to get a "dual certificate" so we can also teach in Boston during the winter.)

I think most Philadelphia metro and suburban schools will be closed just tomorrow, and some may have a delay Tuesday, but crews will get it all cleared by the end of Tuesday.

Will be posting in the next day or two a detailed wrapup of the 2005 Blizzard, why it happened, how the computers missed it, and what are the factors which can lead to this repeating in February for a larger portion of the East Coast. No joke. If three hurricanes can hit Florida in one month, is two Blizzards impossible? I am concerned about what is coming Wednesday. A quick snapshot of the satellite shows a very active stream of moisture from DEEP in the tropics heading north, with another series of shortwaves heading southeast around the Rockies high pressure ridge. Something smells fishy in the forecast, yet again. If BCPS bows to the pressure of it's neighbors, (fingers crossed, wearing lucky wool slippers, while eating a fruit cup) then I'll have more time today to analyze this situation.

Congratulations New England Patriots and Philadelphia Eagles.... what a weekend it has been. One of the most exciting Superbowls in a long time is now on the table, occuring in a month which may go down in weather history as the most exciting in it's own right.


Sunday, January 23, 2005

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TWO ROADS DIVERGED IN A YELLOW WOOD,
AND I TOOK THE ONE LESS TRAVELED BY,
AND THAT HAS MADE ALL THE DIFFERENCE
- from "Stopping by a woods on a snowy evening" by Robert Frost

As of January 26, this site will be been on the air one year. It has been an amazing time, and I look forward to the increasingly interesting weather coming for the remainder of our lifetimes. I enjoy big storms, forecasting big storms, and most importantly, providing information that helps you be safe in the big storm.

So as we turn the corner and go into the second year, it is time to pause and get your input on what YOU want to see with this site. I run this just like my trips with the Dundalk Adventure Club. We find out what kind of trip the kids want to do, then put out some proposals, and they decide on the trip. So think about some ideas that can help the site be more informative for everyone. Consider recommending any specific links you'd like to see, what areas of the Northeast do you think need better forecasting coverage on this site, etc.

Remember the primary focus is the I-95 corridor, except for when tropical systems threaten the U.S., or if a snowstorm would hit the southeast (haven't forgotten about you central Alabama).

I will explain the meaning of the headline when I can post the pics I took in the storm out here at Seven Springs.

Change in snowfall forecasting

1. Accumulation predictions will be a straight number for a city or specific area, such as
"12 inches for Philadelphia" or "8 inches for York County" the caveat is that forecast implies their may be a 2 inch variance on either side of that number.

2. I will begin grading the accuracy of the forecast based on a percentage system. How close in percent was the actual accumulation to the forecast. If Philly gets 11" and I said 12", then it is about 90% accurate, which would be an A. York County, if I said 8" and the actual was 5" then 5/8 = 60% roughly? That's a D which in my book is not really passing. I will grade all my forecasts when the storm is over based on the LOW number to be consistent.

3. I'll do an average roundup of all the predictions for a final storm grade based on percent accuracy.

About the comments

1. SPORTS AND WEATHER. I used to drive my parents nuts (right Mom?) about the weather at home back in the day. I was probably one of the first viewers of the Weather Channel when it came on the air... (anyone know the date? ah, good guess.. it was March 1, 1982). So I get as emotional and OCD about the weather as sports people do about their teams. So my fellow powderhounds in Beantown... IT IS OKAY to let your emotions spill over onto this site about your sports teams. In fact it helps to broaden and diversify our viewpoints on life, as my family would vigorously nod their heads were I to say there is more to life than weather. My statement about the Steelers country servers was just to throw a snowball at you for fun. Then again, it's so powdery, I can't make snowballs.

2. STORM REPORTS. I think other viewers really seem to enjoy reading the storm reports from far away. Us PH's love a good snow, even in July. Just hearing about it. And the NWS reporting system is not ideal, so it helps us understand the dynamics of the storm with your observations. Keep on postin' !

LOOKING AHEAD TO THE NEXT BIG STORM

Fear the Florida Factor. I am running out of internet cafe time, so this is a preview of my next big call, which is not hype, it is grounded in science. Bostonians, get your seatbelt out. I think this storm was only a setup for what is coming in February. Florida provided that lightning strikes twice, or three times, or four times. Water temp profiles off east coast are running 4-6 deg C above normal. That's why you'll have 25-30" in Boston today.

So the early word on February, another storm bigger than this one, believe it or not. More later.

Saturday, January 22, 2005

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"I'M MAKING FRESH TRACKS ON INTERSTATE 95."

That is the headline of the day from my friend Mike Arles, who make an almost 8 hour trip through the southern part of the storm.. Williamsburg, VA to Philadelphia. But Mike is home safe now, thankfully.

I only have a few minutes at this point, and will do a quick roundup of the major issues right now, then a larger post this evening. I would like to write more but it costs $ to do that at a ski resort. And we have super great lake effect right now so I want to get back out and make some fresh tracks of my own:

STORM ROUNDUP (from Southwest to Northeast)

Pittsburgh/Allegheny Mountains/Altoona-State College
The worst may be over, accumulations fell in the lower range, closer to 6-8 than 12. Lake effect will add to that in the traditional snowbelts areas, pushing their totals another 1-2 inches higher.

South Central PA- Central Maryland-Baltimore Metro
Hopefully the 8-12" call was not too far off the mark. I heard 7 inches in Dundalk, and a shortwave swinging southeast might do a little surprise number on the heels of the secondary low. Big problems with blowing and drifting snow Sunday and Monday. NO SCHOOL Monday for anyone in the Baltimore Metro area. The reason I will explain later, but trust me on this. If you get any more surprise snow, there's a 2-hour delay Tuesday or possibly even closed.

Philadelphia Metro
9" in suburbs, probably more in the city. May fall short of the 12-15" call, but there is still wraparound possibility, and the shortwave. Winds and blowing snow tonight and Sunday may reach Blizzard Watch criteria. Power outages likely. The game will go on as scheduled. School?
At least a 2-hour delay for most Phila metro schools

New York City
Here's aiming big guns aiming at you, baby. Too many details right now, but the basics are:
- power outages, winds 35 mph plus and snowfall rates of 2-3" per hour in the next few hours until early Sunday. Impossible for crews to do anything about the snow until late Sunday. NYC will resemble scenes from Day After Tomorrow, at least in appearance. City will be pretty much shut down for 6-12 hours. Total snow... 10-15 in city, 15-25 along the Island, 25+ inland areas north of Long Island.

Boston
Here's aiming MONSTER BIG GUNS.. YOU ARE THE BIG KAHUNA. SAY GOODBYE TO FEB 1978, YOU WILL BREAK YOUR RECORD. It is not inconceivable to hear 30" reports in downtown. These winds mean business, gusts to storm force (55mph+). They might use Fanuiel Hall (sp? I'm tired) for scenes in Day After Tomorrow II. Snowfall rates 3-4" an hour overnight Sunday. Thundersnow and Lightning due to excessive lift rates. I am not making this up. Waves 5-10 feet in the harbour. Massive power outages and collapsed roofs from weight of snow. Significant threat to safety of elderly who may not be accessible for days. (Did you check in on Grandmother yet?) . Snow ratios 30:1, schools closed for the entire week. I am pinching myself. Now I pinched the person next to me. Am I really writing this?

Although a massive, crippling storm like this is a serious threat to health and safety, if you take the necessary precautions to protect your family, it can be the most significant event of your life. The Blizzard of 83 in Philly is the catalyst that got me into weather. Ask my mom, she's the one who posted earlier today.

So much more to write about, so little time. The slopes beckon. You Beantown guys stay safe, take some pictures, I want to hear about snowfall rates and wind speeds, the whole kitchen sink and more. You keep commenting until your fingers hurt, because hundreds and possibly thousands of fellow powderhounds are reading what you write. In closing..

BOSTON... YOU ARE NOT JUST THE BOMB... YOU ARE THE THERMONUCLEAR BOMB. From this moment forward, you guys will be in the Foot's Forecast Hall of Fame, and I will do specific projections for your area just like I do for my area. You're earned this badge of courage.

Gotta go... next post late tonight.

Friday, January 21, 2005

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IS THIS "THE DAY AFTER TOMORROW" OR WHAT?

WHEW! I don't know where to begin. You probably have whiplash from just trying to keep up with the earth-shattering changes in the forecast since early Friday morning. I only have a few minutes to do a quick analysis and respond to some great comments and observations.
The storm does seem to be taking on almost a mythical aura as it has turned into the most monstrous looking "clipper" I have ever seen in 20 years of following and forecasting weather.
I think the original ideas about this storm are beginning to pan out, best summarized in
"The Final Word" I issued Friday morning:

QPF (liquid equiv in atmosphere) will be HIGHER than expected, temps will be COLDER than expected, the primary low will eject off the coast a LITTLE SLOWER than expected, thus everyone will receive slightly MORE than forecasted.

That certainly seems to be the case with the entire I-95 corridor... GO BOSTON AND NEW YORK CITY/LONG ISLAND/SE NEW ENGLAND! You take the prize for the most rapid about face in a forecast I think I've ever seen. Snowboards call it catching air, I think the NWS guys at Upton were probably spun around so fast by the model changes that they did a 720.

SO WHERE DO WE GO FROM HERE?

1. Please continue to post your observation if you can, in between shoveling and resting with those neat back warmer things. Kids... go out and make money with this storm!

2. Will accumulations change again from here? Now that the ante has been upped all to Day After Tomorrow Status (NYC, Boston getting pummeled with crippling historic blizzard), I don't know how much farther up they can go..but it is possible some areas top 3 feet with the way this is panning out.

3. You can tell we've entered the twilight zone of forecasting when you start seeing calls like: "Total storm accumulation 1-2 feet" it's what the kids call "off the charts." The snow ratios will probably end up being 30:1 in New York and Boston, 20:1 in Philly and Baltimore.

4. Is there a chance this busts like the March 2001 NOstorm and falls apart? We had a similar forecast that time for 12-24 inches across PA, NJ, NY etc, and it never materialized. The difference this time is our primary storm has already demonstrated it is loaded with moisture, and moving quickly. That forecast 4 years ago busted because the expectation was a big blizzard would form ON the coast, with no preceding storm. We will have a monster storm ARRIVING at the coast already a force to be reckoned with.

A QUICK ROUNDUP OF ANSWERS TO YOUR QUESTIONS

First of all, you guys and gals all make me blush. I do this because I love storms and enjoy keeping my friends, family and colleagues well-informed so they can be safe. Out of admiration and respect for my fellow powderhounds in Beantown, I will be adding a variety of features in the links column so you can get a regular storm info fix for the short term and long term. And I'll add a NWS link for you as well.

Woburn! My heart goes out to you as my Environmental Science class and I did an in-depth study of the W.R. Grace situation. As you can probably see from the recent changes, most of Mass is going to get hammered, so 12-24 might be LOW for Boston as QPF's are 2.5+ just off the Cape. If that shifts ever so slightly west, with those high ratios, Good Lord you could see historic amounts of snow. 30 inches is not unrealistic.

How did I know about this a week to 10 days out? I trust my instincts and compare the pattern to previous storms I have forecasted, won or lost. And since I am not the government or private industry, I can say what needs to be said in a professional way and not worry about upsetting my boss, or department, agency or co-workers. The real boss is the Lord and the weather he creates. You and I are just the happy recipients of the blessings he will let us enjoy for a couple days here. So everyone be safe, take your time, and stop for a moment to take it all in for what it is worth.

Because February may have something EVEN MORE dramatic in store for us. (drum roll.....)

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SOME THINGS ARE TRUE
WHETHER YOU BELIEVE
THEM OR NOT...PART 2 

JANUARY 21, 2005
THE FINAL WORDS ON THIS STORM: STAY THE COURSE

PREPARE FOR SIGNIFICANT SNOW IN MAJOR CITIES OF THE
I-95 CORRIDOR, NEW JERSEY AND INTERIOR PENNSYLVANIA

Reasons for my snowfall predictions:
1. While western origin storms do not usually bring a lot of snow to the East Coast, the situation continues to be the high snow-to-liquid ratios due to the entrenched cold air and a fresh supply of Arctic air in a nearby high pressure to the north.

2. The NWS is holding back or staying conservative because their flagship model, the GFS is doing that. What you see above is the ETA, which is more in line with what I see most TV stations and Accuweather going with. The farther away from DC you get, the more that I see forecast offices being willing to consider other models in their call. If you spent millions of dollars of taxpayer dollars on a ground-breaking computer model, would you disregard it in the shadow of Washington DC and opt to follow other programs?

3. Waters off the Atlantic Coast continue to be above normal. This will allow for more moisture to be pulled into whatever coastal low develops, even if it is weak.

4. Daytime and overnight temperatures will be colder by 2-5 deg F than forecasted throughout the northeast. This will lead to a bump in accumulations from 2-4" depending on where you live.

QPF/SNOWFALL ANALYSIS
I agree with the prognostication of many readers who have posted, especially Philadelphia, York County and Boston. There seems to be the feeling that when a snowfall amount that is generally "less than a blizzard" is made, the reality ends up being a bit more than that. Contrast with March 2001, when everyone was calling for the end of the world (24-36"), and major cities saw a few inches at best. Contrast THAT with the 2003 Blizzard and many a New England Nor'easters, all of which were either going to go south or out to sea.. then you woke up to 6-12" and more coming. Reminds me of the famous phrase I once heard someone call into to a TV Weather Station: "Mr. Forecaster, could you please come to my house and help me shovel the 6 inches of partly cloudy on my driveway?"

In the final analysis... I think QPF (liquid equiv in atmosphere) will be HIGHER than expected, temps will be COLDER than expected, the primary low will eject off the coast a LITTLE SLOWER than expected, thus everyone will receive slightly MORE than forecasted.

Here's my final QPF/snow breakdowns... might be slightly different to account for adjustments in liquid forecasts. Then I am off to school and the ski trip. Next post late tonight from Seven Springs Resort.

Boston: .50/15/25:1/6-12" (slightly more than the banner listed at top)
NYC/Long Island: .5/20/20:1/8-12" Philadelphia: 1.0/25/15:1/12-15"
Pittsburgh: .75/20/20:1/12-18" Interior/Central PA: .75/20/20:1/12-15" (incl. York County)
Baltimore: .75/25/15:1/10" Washington: .5/30/10:1/4-6"
Richmond: .25/30/10:1/3-5" Norfolk: .75-1.0/35/2-4" then rain

Please continue to post your questions and observations once the fun begins! I will do my best to keep you updated throughout the storm from where I will be this weekend with my students.

Thursday, January 20, 2005

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SOME THINGS ARE TRUE
WHETHER YOU BELIEVE THEM OR NOT

That would be the line for the National Weather Service this morning. These people do work very hard and are very good at what they do, it is just a matter of interpretation. Who among us is interpreting the computer models the most accurately? Only time will tell. If I am wrong and this is a major bust, I will be glad to post for all to see a picture of me wearing my bag, which I have worn a couple times so far this winter. Today's post will be the last detailed analysis on this storm, as I go into trip mode for a departure to Seven Springs Ski Resort in western PA. I will post from out there sometime Friday night. Read over the previous columns to understand the evolution of the storm.

Here is the morning picture show to drive home my point that this will be in the top ten or twenty all time big snows for the Mid-Atlantic and Northeast, similar to January 1996, though not as much snow. I still see the signs that could turn this from a pesky 12" snowfall into a monstrous 24" wipeout for much of the battleground zone I have outlined above. The best indicators of how this will play out in your backyard are going to be:

1. QPF results (Quantitative Precipitation Forecasts) Bookmark that site and check it about every 6 hours.

2. Surface and upper air temperatures. If you notice Saturdays temperatures start out much colder than the forecast, prepare for a lot more snow.

So let me lay it out this way:

HOW THIS COULD BECOME A BIGGER MONSTER As discussed in detail Wednesday, if the liquid equivalents end up a lot higher than we expect, due to enhancement from the Gulf and the Coastal low being slower and closer, then this can easily double to a 24" storm for "the zone" indicated above. If the expected handoff from the Midwest Low to the Coastal low occurs quickly, that allows for faster development and solid 24 hour period of snow. This is where you get the big prizes of 38 inches in York County such as in the 96 Blizzard as reported by an alert reader.

HOW THIS COULD BECOME A BIG DISAPPOINTMENT Though this is not as likely, it is possible that for some unknown reason, the western Low stays stronger, and burns out all it's snow on the Appalachians. It's happened before, and powderhounds should always be on guard that western origin storms are suspect for not panning out as we think they will. The eastern moisture never gets into the act, and the coastal Low is weak, forms too far out to sea, or never forms. What was going to be 12-18 inches ends up just 3 or 4 in the big cities and the real story is the lake effect snow in western PA and MD. Again this is highly unlikely.

So now is the time to begin preparing, for the snow will arrive in western PA Saturday morning, central PA and MD by noon Saturday, eastern PA and MD by Saturday afternoon.

A quick early evening post tonight, another brief morning picture show Friday AM, and then it is off to the races!


Wednesday, January 19, 2005

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PREPARE TO GO NOWHERE FAST

SEVERE WINTER STORM TO CRIPPLE PARTS OF THE MID-ATLANTIC
AND EAST COAST THIS WEEKEND...BLIZZARD CONDITIONS POSSIBLE

FIRST, a check of where we stand with public knowledge of the storm:

- a Marty Bass alert has been issued. A Baltimore area TV forecaster, Marty is getting ramped up from what I hear, starting to drop hints about the storm.

- Carl Parker on the Weather Channel has been particularly adamant this evening about doing a "up play-down play" on this by saying things like: "There's the potential for a huge snowstorm to develop this weekend for the Mid-Atlantic." And they keep saying this about every four mintues. You know that when Paul Kocin gets on there, it's a serious situation. If you don't know who these people are, it's okay, you're probably a normal person.

- As of Wednesday afternoon, only the Baltimore/Washington and New York City NWS offices issued Special Weather Statement Wednesday afternoon. All other NWS offices held back until Thursday morning. State College, Philadelphia and Pittsburgh now have come out with their Winter Storm statements. Read their forecast discussions: (scroll down a page to get the weekend analysis), very interesting to see how they all still carefully avoid even talking about the liquid-to-snow rates. PIttsburgh, State College, Philadelphia, New York, Baltimore.

- Accuweather is calling it what it is... a major winter storm, and has a series of graphics on their site which would indicate the I-95 corridor is going to the under the gun either way. And it appears they believe a secondary low will develop off the SC coast and more northeast, delivering a wrap-around punch of snow over the big cities of the northeast.

- Mainstream media outlets, such as MSNBC, local TV station websites, etc. have not begun advertising the storm, but I think that will start to change in a big way Thursday. By Friday everyone will be in major hype mode, and the NWS will roll out Winter Storm Watches for most of the Mid-Atlantic.

SECOND, what will be the evolution of this as a significant snowfall event?

- Liquid to snow ratios will be generally 15:1 and 20:1 in higher elevations, due to the Arctic air being delivered by the clipper which just passed and the next one on Thursday. I think highs throughout the Northeast will in the lower 20's.

- The current QPF (Quantitaitive Precipitation Forecast) as put out by the Climate Prediction Center (CPC) is calling for a general 1.0 to 2.0 avaiable liquid because it appear likely Gulf moisture will be drawn into the first system diving southeast from the upper Midwest on Friday-Saturday, and then Atlantic moisture will wrap-around the second system on Sunday.

- A ridge off the Southeast coast is going to slow forward motion of the east-moving low, so the Mid-Atlantic will get a longer duration event on Saturday into the evening before energy transfer begins and the second low cranks up as it moves north from the VA/NC border.

- Colder air means more snow. While a forecast is more complicated than some simple calculations, I do base my snowfall amounts on the tried-and-true formula that gave us 23.5 inches in the Feb 2003 Storm. It is the snow ratio as determined by the air temperature, X available moisture. A rule of thumb in snow is that 1" of rain is 10" of snow at 32 degrees F. But the colder the air, the more snow you can squeeze out of the same parcel of air.

Let's say the average available moisture in this storm for the Mid-Atlantic (including all of PA south of I-80, all of Maryland from DC north, all of DelMarVa from Dover north) is 1.25 inches of liquid. Now take your location... if you are near the coast, temps are warmer, around 25 F, so you'll have a 15:1 ratio. In the mountains of PA and MD, where temps will not crack 20 F, it'll be 20:1 and possibly 25:1 at ski resorts like Seven Springs, Blue Knob, all of the Poconos, Whitetail, Liberty, Roundtop and so on).

Do the math...multiply 1.25 by the ratio of your area, to get your projected snowfall:

Northern Virginia/Northern West Virginia/Southwest PA: 1.25 x 25 = 31 inches. Not impossible, given forecast highs of 18 F around Pittsburgh, and liquid equivs topping 1.5 inches. Probably more like 18-24"

Central PA south of I-80: (Cold, highs in 20's, but slightly less moisture)
.75 x snow ratio of 20 = 12-15 inches anywhere from Altoona east to the Blue Route/Northeast extension, including State College, Harrisburg, Lancaster, Selinsgrove, Chester County, Bucks County, Allentown.

Southern PA to Northern/Central MD, the I-76, I-83, I-70 corridor: (Saturday Highs in mid 20's, but more moisture) 1.25 x snow ratio of 15 = 18.75, so I'm calling for a general 12-18 inches, with some localized amounts in the lower Susquehanna Valley near 2 feet. That would include York-Franklin Counties.

All important I-95 corridor from DC to NYC: (Saturday highs in upper teen's NY, lower 20's south, moisture will be over two storms, Saturday system, then Sunday system) 1.25 x a snow ratio of 10 south, 15 north means a general range of 12-18 inches from metro DC north to metro Philly on the ground by 8pm Sunday.

Northeast/New England from NYC to Boston: (Sunday highs in teens to low 20's) This is more tricky, because these areas will be affected by the second and third systems coming north from the VA/NC border, bringing hefty moisture. CPC has a liquid equiv of 2-3 inches just off shore NYC on Sunday, which would pretty much be a rerun of "The Day After Tomorrow" That's 2.0 x a snow ratio of at least 15 = 30 inches! Seems crazy but then again who would have forecasted 30.7 for Philly in the 96 Blizzard?

THIRD, how would this kind of snowfall affect schools?

The historical pattern in Maryland seems to be that it takes one full workday for maintenance crews to clear 5" of snow. It is a tremendous amount of work, and they go sometimes two full shifts to get it done. That means for every 5", you are going to miss one day of school.

So the early no brainer call is: NO SCHOOL MONDAY for the vast majority of students living throughout the Mid-Atlantic, (except for Garrett County, MD, which got 50 inches in Feb 2003 and never lost a day of school)If 10" then a delay on Tuesday. If 15" school is closed Monday and Tuesday, 20" is closed until Thursday, and so on.

AND FINALLY, answers to your comment questions:

1. Dad, flight should be fine, but will be delays as PHL is going to have tough time keeping runways clear. Height of storm is Saturday night-Sunday AM.

2. MA...when the hype starts on Friday, you'll start having more believers. They'll really believe you when they are shoveling 15 inches.

3. York County...20 to 30 inches is not out of the question if the air is colder than we anticipate and the liquid equivs go up above 1.25. Blizzard-like conditions are possible on Saturday night-Sunday, but only in brief bursts when winds gust to near 35 mph.

4. Glenville, PA... yes, drifting is going to be a bigger problem, as this is wind-driven powder that will fluff all over the place. I would imagine drifts of 3-5 feet would not be unusual.

IN CLOSING for the evening, if I am wrong on this, or the snowfall totals do not materialize the way I thought they would, I will keep in tradition with my students and wear a bag. Except this time, I'll do a picture of me wearing the bag on this site, just for fun.

Please note that any previous information posted below is still considered valid. The current post does not supersede a previous post unless I specifically state I have changed the forecast.

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PICTURE THIS...
YOU, A SHOVEL, AND A WHOLE LOTTA SNOW

For our visual learners out there, this is a compilation of the latest and greatest computer modeling on this upcoming potential superstorm. The top row of maps is from the ECMWF, known as the European computer model. The bottom left is the GFS snowfall totals as of 8PM Monday, and the bottom right is the NWS liquid equivalent guidance from Friday to Sunday. Hopefully it is clear enough to read. Enjoy, and go get that extra shovel. With this kind of weather, looks like both NFC playoff games will be verrry interesting.

Next update late this evening. That snow today?... an inch max, slippery at evening rush. That snow Thursday? Nothing, just flurries.