Tuesday, January 18, 2005

IT’S DÉJÀ VU ALL OVER AGAIN, AS WEEKEND
MEGASTORM TO RESEMBLE JAN 96 & FEB 03

If you just want a snapshot view of what I project this storm will do for your area, scroll down to the bottom of this post for details on a geographic forecast for the Mid-Atlantic. (Warning: This is a wordy, long pre-storm post, difficult to read in one sitting.) I will post some graphics on Wednesday for back up the claims made in this forecast.

If you are new to this site, a brief introduction:
I am an Earth Science teacher at Dundalk High School in Baltimore County. I have been forecasting weather at a semi-professional level for over 10 years, and began this hobby/adventure 20 years ago with weather broadcasts on my high school morning TV news program and morning announcements. I have interned at the National Weather Service, forecasted for several semesters at the Penn State Weather Center, and earned an Earth Science degree at Penn State with a concentration in Meteorology and Geology. But I prefer teaching about the weather because it is more fun working with kids than staring at a computer screen all day, which is what meteorologists have to do most of the time.

This site has been in operation since late January 2004. I forecast the weather based on my analysis of the same computer modeling programs and reports that are viewed by professional meteorologists, whether at the NWS, Accuweather, or The Weather Channel. I have been wrong from time to time, just ask my wife! However, where it counts in this business is the big call. I don’t really focus much on the day-to-day weather, just the long term patterns that can give rise to the life-interrupting or -thrilling events we call storms.

I have been successful in nailing several of the most recent big storms in memory:
(Warning: brief resume of forecasts, not a brag sheet)

On Friday, February 14, 2003... I told my colleagues at school that Baltimore would receive 18-24 inches of snow by Monday the 17th, and we would be out of school one week. The total in my backyard at Dundalk: 23.5. The BWI airport: 27. We did not report back to school until the 24th.

On Monday, September 12, 2003, I told my students and colleagues that Hurricane Isabel was likely to charge right up the Chesapeake Bay, and those living near water should consider preparing to leave their homes. It did, and some of my students and their families unfortunately were flooded out of their homes in Southeastern Baltimore County.

My personal favorite is:
In October 2002, I told my Earth Science students there would be snow the first week of December. Then on December 4, a Wednesday, I said to my classes, “Happy Friday!” They thought I was nuts. That night, we had 7 inches, and school was closed Thursday and Friday. 4 days to sleep in…. yeeehaw. Remember that one, Brandon?

METEOROLOGICAL and CULTURAL ANALYSIS OF STORM POTENTIAL

You were warned, that if you did not want to get locked into reading a big long post..then scroll down to the end. Since this storm is going to be one of the “Big Ones” I am going to take license and flesh out all the parameters of this event. (Then again, it could be a big bust too… either way, this will be big.)

The next section is my analysis of the overall situation, taking both climatology and past experience with storm forecasting, as well as the political implications of the forecast’s outcome.

Let’s cut to the chase already… why I believe the East Coast is primed for a major winter storm this weekend.

1. Déjà vu all over again.. I have the same feeling right now as I did for the February 2003 storm. I see similar elements falling into place. The abundant uncertainty that accompanies any big storm forecast by the major agencies, the diverging model trends, etc. etc. But I also see the weather through the forecast:

- Much above water temps off the East Coast. This was present in Feb 2003.

- A series of pre-storm clippers that recharge the area with fresh cold air
- A large blocking high to the north that noses out in front of the storm, slowing it’s forward motion, which results in a higher than predicted snow total.
- Daytime temps for this coming Saturday have been dropping all week… NWS temp forecast is now 24 F for Baltimore, and we’re still 4-5 days away. I’ll bet we barely break 20 F in the final outcome. The colder it is, the more snow there will be… that translates into a TON of snow for PA from Philadelphia to Pittsburgh. Whoever said 18 inches for Philadelphia is not far off the mark, that’s what the GFS is advertising as of late Tuesday evening.

And a final puzzle piece that win the Publisher’s Clearinghouse $10 billion prize for who pegs it first… will this become a PHASED event? If the northern stream storm dives far enough south through the Tennessee Valley to get the southern jet stream involved. If that happens, 2 feet in York County, PA is not unrealistic give the high liquid-to-snow ratios. Imagine how the Eagle/Falcons game will be in a blinding snowstorm... wonder who'll win? Hmmm.

2. Similarities and Differences. This section outlines how this storm is similar and different to notable ones of recent memory, so we can understand how the forecast will pan out over the next 5 days.

SIMILAR: Feb 11, 1983…the bonafide “Blizzard” was also a glorified cold core clipper than dug far enough southeast to tap Atlantic moisture, and just exploded along the coast… giving Philadelphia it’s second all time highest snowfall of 21.3 inches in 24 hours.

SIMILAR: Jan 6-7-8, 1996….a glorified Arctic front-type clipper dove southeast, then got blocked by a monster High off the coast. Sound familiar? Snowfall was mainly in the Ohio Valley, Mid-Atlantic and Northeast, much like the Feb 83 storm, but snow totals were off the charts, 25-50 inches in interior sections of PA and MD. Philadelphia set it’s all time record, totaling 30.7 inches in downtown.

DIFFERENT: Jan 22, 1987… this was your classic southern origin nor’easter, with the New England High drilling cold air down the Appalachians, and the storm riding up from Georgia. Snow fell from Atlanta to Boston in amounts averaging 8-12” in the big cities. This is not likely to happen.

DIFFERENT: Mar 11, 1993… The "Storm of the Century” began as an already intense low pressure over the Gulf of Mexico, then slammed Florida with hurricane force winds and tornadoes. Drawing in cold air from a Canadian High, it went on to shut down every East Coast airport from Georgia to Maine. That is not likely to happen in this storm

IN BETWEEN: Feb 17, 2003…The “President’s Day Blizzard of 2003” will forever rank in the minds of Baltimoreans as the single biggest storm of modern times..27 inches over 2 days. Our upcoming monster will be a hybrid version of this, minus the intense supply of Pacific and (probably) Gulf moisture. The Feb 2003 storm was loaded with 2-3 inches of liquid equivalent, which under a cold dome of temps no higher than 20 F, made for extremely high liquid-to-snow ratios of 1:30.

3. Beware the Blue Bandwagon
A prediction about upcoming predictions. You will notice little whisperings and sidebar comments in the news about this big storm by Wednesday or Thursday. And then… with a drum roll and clash of cymbals, you will get whiplashed on how the NWS is going to suddenly just completely reverse course later this weekend. I guarantee they will come out with all guns blazing about a significant winter storm. I call it the Blue Bandwagon… because for several days, the most of the foreign weather forecast models have been advertising this storm. THEN… out of the blue, the forecast will dramatically change for the worse.
Even the JMA… the JAPANESE Meteorological Agency has a model predicting this. But the US-based GFS? Eh, can’t be bothered. Now come on, when a computer model program IN JAPAN is predicting a major storm on the US East Coast, it is time to get with the program.

4. Let’s Share and Compare
Read for yourself recent comments made “internally” by the NWS but posted on their respective sites. It is called the “Forecast Discussion” and gives you a better glimpse into what forecasters are thinking with what they just issued to the public, as well as their analysis of what’s coming. Notice how they seem to cleverly avoid mentioning the European or UKMET models too much, which are both advertising a major storm of nearly historic proportions. Granted this is 4-5 days away, but the GFS is the first computer program to accurately predict the March 93 storm 5 days in advance.

Philadelphia.. 9:45 PM Tue.

MAIN CONCERN FOR THE LONG TERM IS THE POTENTIAL STORM FOR THE WEEKEND. THE UPPER SYSTEM PROGD TO PRODUCE THIS IS STILL WELL OUT OVER THE PAC OCEAN SO A LOT CAN HAPPEN BETWEEN NOW AND THEN. HAVING SAID THAT...RECENT TREND OF THE GFS IS TO TRACK THE SFC LOW CENTER A LITTLE FARTHER N AND A LITTLE DEEPER...SO WE HAVE KEPT A CHC FOR PCPN SAT THRU SUN. CURRENT FCST IS FOR ALL SNOW BUT THERE ARE SOME INDICATIONS FOR MIXED PRECIP OVER THE SRN PART OF OUR CWA.

Baltimore…9:00 PM Tue

THE WEEKEND SYSTEM IS BASICALLY A LARGE CLIPPER FOR OUR AREA. THE GFS IS A LITTLE FASTER THAN THE ETA...BUT BOTH VERY SIMILAR AND THE GFS HAS GREAT RUN TO RUN CONSISTENCY WITH IT. 12Z EURO JUST IN AND ALSO SOMEWHAT SLOWER THAN THE GFS. A SFC LOW TRAVELS OUT OF THE DAKOTAS WITH A LARGE AREA OF WARM ADVCTIVE FORCING AHEAD OF IT. EDGE OF PRECIP BY THE GFS TIMING HAS IT REACHING OUR FORECAST AREA IN NW MD EARLY SAT MORNING AND OVER THE ENTIRE AREA BY LATE MORN SAT. THE LOW UNDERCUTS US ALONG THE VA NC BORDER...AND TRANSFERS ITS ENERGY TO THE COAST WHERE A SEC LOW TAKES OFF AROUND ORF. THE BULK OF OUR EFFECTS FROM THIS LOOK TO BE FROM THE PRIMARY LOW. WITH THE PRECIP FROM THAT MAXING OVER THE AREA MIDDAY SAT THRU MIDNIGHT SAT NIGHT. IF THE UPPER TROF CAN GET MORE NEG TILT THAN IT CURRENTLY IS FORECAST TO HAVE...THEN THE COASTAL COULD SLOW IT/S DEPARTURE AND SNOW COULD LAST WELL INTO SUNDAY. AT THIS POINT IT DOES LOOK LIKE WE DO GET INTO THE COLD CONVEYOR SNOWFALL ON SUNDAY FOR A TIME...BUT THE DURATION AND STRENGTH OF THE UPPER TROF WILL BE CRUCIAL. AT THIS POINT AM LOOKING FOR A LIGHT TO MODERATE EVENT SAT INTO SUNDAY.

Richmond…3:00 PM Tue

BELOW NORMAL TEMPS WILL CONTINUE TO BE THE RULE THRU THE EXTENDED FCST...WITH THE POTENTIAL FOR A SIGNIFICANT STORM SAT AFTN THRU SUN. MDL TRENDS HAVE BEEN SHOWING SYS DIVING FM UPR MIDWEST EWRD TO THE OFF THE MID ATLC CST SAT THRU SUN. THE LAST COUPLE OF MDL RUNS HAVE THIS SYS TRACKING FARTHER N...THUS SHOWING WRMER AIR BROUGHT INTO THE SYS AS IT APPROACHES OUR REGION...THEN TURNING COLDER AGAIN AS SYS EXITS OFF THE CST AND OUT TO SEA. SO...AT THIS TIME...HAVE INTRODUCED CHC OF R-/S- INTO SRN CNTIES DURINGSAT...THEN EXPANDED IT NWRD TO ALL AREAS EXCEPT EXTRM N CNTIES SAT NGT THRU SUN MORNG. HAVE KEPT JUST CHC OF S- FM N OF RIC ACRS TO OCN CITY MD THRU THE ENTIRE EVENT.

Pittsburgh…2:15 PM Tue
HIGH PRESSURE BUILDS INTO OUR AREA FROM THE NORTHWEST DURING THE DAY ON FRIDAY. FRIDAY NIGHT THROUGH SUNDAY LOW PRESSURE SWINGS SOUTHEAST THROUGH THE MIDWEST...THEN EAST ACROSS THE LOWER OHIO RIVER VALLEY...AND FINALLY OFF THE CAROLINA COAST. STRENGTH AND TRACK OF THIS LOW WILL DICTATE PCPN TYPE AND/OR SNOW AMOUNTS. PRESENTLY WE ARE GOING WITH THE COLDER SOLUTION AND KEEPING PCPN TYPE AS SNOW. HIGH PRESSURE BUILDS BACK INTO OUR AREA FOR MONDAY AND TUESDAY.

5. And finally, those who don’t study history ….
The February 2003 storm caught many by surprise from the swiftness in which it changed its colors. Those in Maryland remember how you first got a couple inch preview on Saturday, then it stopped. The Weather Service AND the Weather Channel were still saying, “It’ll go south, from DC down to VA.” I was in Altoona, PA watching all this and thinking that the storm was going to stay south and slow down.

Thus, we could sleep in from our long day of skiing and take our time getting home Sunday. The next morning, we awoke at 6:30 AM to a winter wonderland. There was already 2-3 inches and it was coming down hard. Marylanders awoke to 6 or more inches of fresh powder, with another 18 on the way. So much for the going south theory. I just don't think this storm is going to head south either and miss the major metro areas.

So in the final analysis, I believe anyone who disregards this storm does so at their own peril.

ABOUT YOUR COMMENTS AND QUESTIONS

Thank you to all who posted such interesting and thought-provoking comments. If you have read along this far, congratulations on your patience. If you skipped directly to this part, that's okay too. Let me just say that while any forecast is speculation, this one is not without a lot of historical comparison and detailed analysis of the big picture. I believe the elements are in place to create a storm of historic porportions. I would not lead you astray and falsely hype something. The major media outlets were stung by the March 2001 debacle... where they called for the end of the world (24"+ in Philly, for example, and it was 4 inches). So in the years since, they have learned to be cautious and not excessively hype the public over big storm prediction.


As for snowfall... I know other forecasters would never go out on a limb and give you real hard numbers this early. But I am going to trust my instincts and just use simple math. The CPC (Centers for Climate Prediction) is projecting a general .90 to 1.20 inches liquid as a general range for the Mid-Atlantic in this storm from 8PM Friday to 8PM Sunday. Be sure to click on that link and see the liquid equivs map... it's fun and scary. If the snow liquid-to-snow ratio is 1:20 at daytime and 1:25 at night, then it is easy to see how anyone from Virginia to the PA/NY border can get 10 to 20 inches or more. So yeah, if you were going to get that snowblower or bag of salt, I figure you have one more day of "pre-hype" before word of this storm gets out and it is all over the news.

SYNOPSIS OF STORM EVOLUTION

I believe the Mid-Atlantic, Ohio and Tennessee Valleys will be affected by THREE separate low pressure systems … the FIRST is diving southeast Friday that will lay down an advance cover of an inch or two, while the SECOND low develops over the Tennessee Valley and draws in Gulf moisture… though NOT as much as the Feb 03 storm. The first low fades by Saturday night, the second low moves toward Virginia, and a THIRD low begins to develop off the NC Coast. It is these two lows, plus the high to the north, that will form a classic “triple barrel” situation that rides rich Atlantic moisture in over PA and MD into a dome of very cold air. The result... easily 2 feet.

PRELIMINARY STORM FORECAST FOR THE MID-ATLANTIC

Virginia/West Virginia: Northern mountains to get hammered… snow begins early Saturday morning, continues through the evening. Totals above 12 inches in higher elevations, including the southwestern PA mountains and ski resorts such as Seven Springs will see totals above 12 inches by daybreak Sunday. Coastal SE Virginia to escape brunt of storm, with light snow and rain mixed.

Maryland… Western: The traditional snow counties of Washington, Garrett, etc, will also get hammered with 12 or more inches by Sunday morning.

Central MD: Baltimore metro and surrounding counties to see snow increase in intensity throughout Saturday, accumulating 3-6” by midnight. Once secondary and third low develop, another 6” on top of the first snowfall by mid-day Sunday. If the third low is slower to develop, and moves slower than expected, totals will easily top 12 inches.

Eastern MD: Snow begins by late Saturday, continues overnight, accumulating 2-3” by daybreak Sunday. As lows approach, there may be a lull, followed by another pulse of snow as the wraparound effect of the departing low drops it’s heaviest load of perhaps 6” or more.

Southern MD: The tricky part is here. If the double low sets up, areas inside and near the center can often be shut out of any snow at all. I think the SE Chesapeake and Tidewater of VA where my Aunts Sandy and Helen are get away with light snow/rain and fog as the center of the low passes over them.

Pennsylvania… At this point, it appears that almost the entire state has the potential to be crippled as it was in the 96 storm, due to the double/triple barrel effect that sets up this massive conveyor belt of snow directly from the Atlantic. I think the core of heaviest snow, if I follow the GFS current printout, is fully 7/8th of the state from Philly north to Scranton, west along I-80 to Meadville, south to Pittsburgh, back east to Philly. I am not kidding, the GFS has 18 inches plus mapped out for this region I described. That could change, but given high snow ratios of perhaps 1:20 to 1:30, and .75 to 1.25 inches liquid... just do the math. (.75 x 20 = 15" on the low end). Skiing in the Poconos? Better get there by Friday night, plan to stay until Monday. My advice: Get to the store by Thursday to beat the storm crowds.

Delaware…same as eastern Maryland. Potential for a coastal backlash as wraparound snow on Sunday night brings another quick 2-3” on top of 6-9 inches.

New Jersey….due to the nature of the double barrel conveyor belt, and proximity of the state to the coast, it is possible that coastal locations like Atlantic City see some mixed precip, but not a lot of snow, which will be more the farther west you go towards Philly. Accumulations: 3-6” in western NJ, less than 3” in Eastern. Of course the storm could expand and include Jersey in the belt, in which case totals are closer to 6-12".

New York…There is always the potential this conveyor belt idea shifts a tad bit more north than we think it will. If that happens, southern interior NY gets into the act, with 6 or more inches. If there is a sharp cutoff to the precip, it might look like the storm is simply obeying state lines, and bulk of snow stays south. The low would have to really ride the coast to deliver big snow to the Southern Tier.

Coastal New England.. I think Boston and extreme eastern Mass get just clipped by this, with more wind and cold then snow. Perhaps Martha’s Vineyard gets heavy snow, but not for downtown Beantown.



WHAT TO EXPECT ON THIS SITE THE NEXT 4 DAYS

I will read your comments carefully and try to address all questions in a general post during the evening. Here's what I plan to do with this storm:

Wednesday night: Detailed maps of snowfall and storm evolution

Thursday night: Final predictions for snowfall totals and school closings next week

Friday night: No post until probably 9 PM as I will be at Seven Springs Ski Resort, hoping to get snowed in at a resort for once in my life.

Saturday night: Live update from the heart of snow country. Once the storm plays out, it should be a fun time to post some pics for you of the condition out there.

And so it begins!



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