Tuesday, December 28, 2004

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I am so embarassed to report that while I did originally suspect a coastal low off the Virginia capes, I backed away from that claim, and thus my two Aunts.... Sandy and Helen in Hayes, VA of Gloucester County... got walloped with 6 or more inches. This one caught everyone by surprise, including the NWS. Here's the email from Aunt Helen I received Monday night.

"Havin some fun in Ole Virginny! Rich, I didn't hear from you about this one! Seems to have caught everyone by surprise! Right now at 2:25 p.m. we have at least 6 inches and it's still snowing furiously! Hope everyone is keeping safe. I had to prove to you that we got blasted, but if you were to watch the weather channel, you would never know! "

Yet another part of the country to see surprise snow to the delight of many children, adults, (and pets).

Saturday, December 25, 2004

1 comment:

Would you ever expect to use the words "snow" and "palm tree" in the same sentence? The people of South Texas... from Brownsville to Corpus Christi to Galveston, have enjoyed their first white Christmas since 1918. Congratulations, y'all...accumulations ranged from 3" along the coast to 13 INCHES at some inland areas. Unbelieveable. There are some stunning photos on the local TV news station gallery, which you can access with this link. You'll want to show all your friends, because snow on palm trees is a once-in-a-lifetime picture. Just imagine the fun, building a snowman on the Gulf Coast, with palm branches for arms! Read this interesting article from a South Texas newspaper for more details and photos.

New Orleans did not get anywhere near that kind of snow, but did have flurries, light accumulations and icy roads, as reported by the Times-Picayune. The late Christmas deliveries continued, dumping nearly 6 inches on eastern Massachusetts and in the Canadian maritimes.

Where I am in State College, PA we had two ZEROS Christmas morning... it was 0 degrees F at 8 AM (an overnight low of -3) and 0 inches of snow on the ground, like the millions of other people around the east coast. Someday, around the next ice age, we'll get snow eventually.

Merry Christmas everyone, for those not wanting the cold, a brief warmup is coming next week.

Thursday, December 23, 2004

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A series of unfortunate events will Grinch out all hope for snow in the Northeast corridor this Christmas. The real story will be the supermaxi cold, and the new ice age that's been unleased in the Ohio Valley. Congratulations Dayton, you've just set your all-time record for most snow in one storm ever in record-keeping. Those of us east of Ohio (including MD, PA, NJ, VA, DE) will feel the effects of this near super-storm because of the lingering snow cover out there. Why? Notice the temperature chart for Christmas morning.

Due to the reflectivity of snowcover, the high pressure system overhead will cool to match the lack of energy at the surface. Thus the cold will get more extreme with each passing day. Friday morning, the Arctic front sweeps to the east coast, and you'll see temps drop 30 degrees, from near 60 today. Dayton will see a low of -12 to -15 Saturday, and the cold will spread out from there, as you can see the influence of the snowcover in central Ohio on the temperature map.

Overall, this will be is the coldest Christmas for most of the nation since 1989.

As for a White Christmas, keep dreaming. Unfortunately that the only place it will exist this year. The rule is: WYHNOTGIWYG. What you have now on the ground is what you get. Blame the Arctic air... it has simply come too far south and too fast, overwhelming the southern subtropical jet in such a way as to keep it mostly offshore. The polar and subtropical jets have to "phase" for a good whopping east coast snowstorm, and there's NO sign of that happening anytime in the next 2-3 weeks.

The only good news for weeping Powderhounds is this great website I found about snow. It's the best I can do for you until the atmosphere gets a little more cooperative.

In closing... I updated the Blue Christmas Roundup in the previous post. Have a great holiday, get some sleep, and I'll check back in with you late in the weekend to see who won the "How Cold Was It At Your House Christmas Morning?" Contest!

Wednesday, December 22, 2004

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The "You" in this case is snow on the ground Christmas morning. This is a Thursday morning update to the roundup for all my customers out there, from south to north. This is a combination of model interpretation and my own realistic assessment.

- Deep in the heart of Texas: Yes Brownsville, your new name will be Whitesville for a day. This'll be the first White Christmas for you since, oh, probably the last ice age. Snow on the palm trees, now there's a sight I would pay real money to see. Figures that one of the SOUTHERNMOST cities in the U.S. gets snow on Christmas. I HOPE YOU ENJOY IT, dangnabbit.

- New Orleans: Yes, Virginia, your name should have been Louisiana, because rain changing to sleet and snow is on the way for your area Christmas eve. First time since 2002 you'll see snow falling out of the sky in the Big Easy. Go dry some water from the marshes 'cause you'll need road salt.

- Florida panhandle: First hurricanes, then tornadoes, then hard freeze, now snow and sleet? Geez Santa, I thought you only put coal in the stocking on just one night, not every night.

- central Alabama: I am going out on a limb here, but I believe the cold air to your north and the system to the south will be close enough for leftover flurries Friday or Saturday. The Bourbon street storm will keep to itself south of you.

- South Carolina: You'll be sideswiped by a mini-coastal Low Friday night into Saturday, but the odds snowfall are low. Perhaps some flurries in the mountains as the cold air charges southeast behind the Ohio valley snowstorm.

- Virginia: Definitely some light snow in the mountains as the front sweeps by Friday morning. Along the coast, rain for the parade.

- central Maryland: Heavy rain Thursday gives way to much colder Friday with flurries, and super cold Saturday. What you see now is what you'll have on the ground Xmas morning. Sorry. Some lake effect in the mountains, but don't hold up hope for snow in Myersville, downsloping will likely evaporate any leftover moisture. Metro Baltimore and DC, natta, zilch, el numero zippo on snow for you Christmas. Okay, I don't have to rub it in.

- Ohio Valley: You win the Super SnowBowl, with 12-20 inches on the ground from the current storm raging. These accumulations will cover most of Ohio, Indiana, and pieces of western PA. After that, frigidly cold. Lows Xmas morning WAY BELOW ZERO.

- central PA: Heavy rain Thursday turning into snow showers at night, with left over light snow Friday, just so you can say. " Hey, I saw on Christmas Eve" after the Altoona church service. No weather problems for Grandma and Grandpa if they want to travel on Friday. Any standing water will have dried up or drained off by the time the cold air sweeps in.

- eastern PA: Some leftover flurries or a touch of light snow as the front passes. Hint of a coastal, but will probably be confined to southeast only.

- I95 corridor to NYC: Rain Thursday, then colder with flurries Friday, clearing and very cold Saturday. Highs not breaking 30, lows in teens to upper single digits in suburbs. Hold on to the shopping bags when leaving King of Prussia, or you'll have unintended recipients of those gifts. Warning to my father: Stay out of the proposal/package lane Friday.

Monday, December 20, 2004

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After Monday's disappointment, this probably seems like ratings hype to you, but it is a forecast confirmed by two different computer models... the GFS and the ETA. And loyal readers like you deserve to get the inside story.

And it's been consistently showing up in model runs for the past couple days. Although it will warm up and rain heavily Thursday, as the Accuweather graphics below indicate, another Arctic front will sweep south. If you though the current blast was cold, this one coming for the weekend is even colder. A gulf/coastal low is expected to form along the front boundary. It is a questionable call for the Mid-Atlantic, though, because I have seen this kind of arrangement before, and two things happened, either:

1) Southern storms have had a tendency to snow themselves out before reaching the NE big cities. Although this storm may be an exception, it is rare to have a snowstorm reach from Texas to New England.

2) The Arctic front moves too swiftly, and like what just happened, all the moisture gets shoved out to sea. The result is a historical storm in the deep south, but the snow never gets farther north than Norfolk. Hence, lots of weeping and gnashing of teeth as the I-95 corridor gets jipped again.

For all of you (like us) who will be gallavanting over the river and through the woods to Grandmother's house, I too shall keep the vigil over the computer models. If it looks like this will turn into a Christmas Coastal whiteout, you'll be the first to know, as it is sure to impact the travel for millions everywhere.

So those of you along I-95 from Atlanta to Boston, don't despair at the heavy rain, and possibly even thunderstorms on Thursday... it is a temporary blip in the Arctic march. You'll see things begin to change rapidly come Friday morning.

UPDATES: I'll do a few blurbs between now and Wednesday night, then Thursday morning a full overview of the Christmas Weekend Storm, if there is one. I must warn you that the next wave of cold air IS COLDER than the current one.

1 comment:
12/20 - 4:25 PM
courtesy of Accuweather.com


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This is a test post to see if I can email posts from school to the website. If so, I can do a better job of updating if we have a rapidly evolving situation.

A few comments about the big disappointment felt across central Maryland this morning...

- Don't underestimate Mother Nature (hint to salting crews)

- Never tell motorists that ice should not form when you know an Arctic front is coming (hint to NWS)

- The more that forecasters downplay a situation, the more likely you'll be surprised by it (hint to public)

- Be prepared for more "character building" incidents this winter as it is now clear districts will not close or delay under the "cold little kiddie" clause. Unless of course parents make their voice heard to their district. My family would hear nothing of this 'too cold waaa.' business. They'd say, "I walked up hill both ways to school in 2 feet of snow while chopping wood by candlelight at the same time." (hint to students and teachers)

In hindsight, would I have changed the forecast? Did I feel foolish as a result?

The answer is: NO and NO. I think the meteorology was there and appropriate for what I predicted. Areas of central Maryland did receive 2 or more inches, but was confined to Anne Arundel County. We did not see as much of the Bay enhanced snow as I expected, mainly due to the Arctic front moving faster than expected.

And I do not use other's misfortunate at their expense, but I am saddened by the many accidents that could have been avoided if the Weather Service had taken the icing potential more seriously. That potential was outlined in this website well before NWS decided to down-play the ice formation theory.

The big loser was of course the snow. The low did form, it did move as expected, and there was more moisture back over MD, especially eastern shore, but those areas had rain longer, which turned into much more ice than central MD received once the front moved through. Thus the reason why schools in lower Eastern shore were closed, which is unusual, and the big city districts were open. This shows a eastward bias in the computer models of perhaps 50-75 miles, and I will use that to your advantage next time we have a storm.

So now the 800-pound gorilla in the room is.... WHITE CHRISTMAS OR NOT?

I know there's probably a few more skeptics out there now, and rightly so. But I have to do my job as a forecaster and forge ahead. I am pleased to report that students did not grumble at me as much this time. Maybe they accepted that we were all equally confused as to why this situation was not "severe" enough to warrant a delay. But you're ready to put this behind you, and set your sights on the reward coming at the end of the week.

So there are three choices...
1. I tell you what the computer models are saying about Xmas Eve and Day.
2. I downplay the whole thing because you are recently stung by this event
3. I just go out on a limb again and stubbornly hold to my ideas...with scientific evidence to support.

I will take my wife out to dinner and ponder on these things, and then get back to you this evening on my decision and forecast for Christmas Weekend.

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Here we are at 5:45 AM, and a few school districts have either closed or delayed, but not the ones that you're looking for. Unless there is an llth hour update or change of heart, it would appear that the big four in Baltimore (Howard, Balto City, Balto County, Harford) have all decided to go in tandem with each other, and send you out into the deep freeze. So prepare your world for bad news.

Who ever said life was fair? At least all you in schoolhouseland only have 4 days this week. Business folk work on Friday. So have that oatmeal this morning, wash it down with hot choc and bundle up, you'll survive. And congratulations Nervous Nellies, you win.

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Pardon the sarcasm so early in the morning...but I'm glad the Weather Service didn't bother to warm motorists about the possibility of black ice, icy secondary roads and hazardous sidewalks. Because after all, "ice should not form due to warm ground temperatures." (this was stated in the Winter Weather Advisory all Sunday)

And pardon the early gleefulness...but Prince Georges and Anne Arundel have now gone with 2-hours late, can we make it a clean sweep of the Baltimore metro area? Charles County has already closed, so at least my "Will it be enough? theory" was enough for them.

Sunday, December 19, 2004

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Last update of the evening. Reports coming in from many areas of light to moderate, wind-driven snow and slick roads. The amount of snow is not really the issue, it's:

Will the combination of bitter cold temperatures, wind chills near zero, winds of 25-35 mph and gusts to 40, and slick roads with a glaze of ice.... be enough to delay schools Monday morning? I think so.

Either way you slice it, Monday morning's commute is going to be unpleasant for anyone, whether they are waiting for the bus, walking to school, driving a long distance or riding a bike. So get to bed early. As for me, I am going to bed soon and dream about a "Series of Fortunate Events" to which I hope to awaken, and be delightfully surprised by what I find on the TV in the morning. Next update at 5:30 AM.
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THE FINAL UPDATE BEFORE THE FUN BEGINS. After much anticipation, consternation, wrangling and general hashing and re-hashing, we have a forecast I think everyone can live with. While the snow amounts have been adjusted slightly, the CONCEPT and INTENT of the forecast remains the same. FOR THOSE WHO JUST WANT THE QUICKCAST WITHOUT ALL THE ANALYSIS, HERE IT IS:

Less than 3" of snow and a thin layer of ice on the ground Monday tomorrow morning in the I-95 big cities from Washington DC north to Philadelphia, which will cause a 2-HOUR DELAY for schools located in rural-urban combo areas, such as: Chester and Delaware Counties, PA south to Howard County, MD, including Cecil, Harford, Baltimore, Carroll, Frederick. Farther north and west, less than 2" and lack of the ice glaze will not interfere with school west of Lancaster County, PA and Frederick County, MD. Exception is the far western mountains beyond Hagerstown and Altoona, which should pickup 2-4" or more in higher elevations.

City schools including Philadelphia, Baltimore, Washington will probably not have a delay due to a slight urban heat island effect. New York and north and east will see 4" or more, and delays are likely but not closures. No matter what happens, travel throughout the NE corridor will be adversely affected by this system for the entire day.


1. Wherever you live, don't stay up late tonight. There will not be much to see... a lot of wind, some rain, some snow and very cold air. I am going to bed at normal time, about 9:30 PM. Make sure you have your winter gear ready for tomorrow, IT WILL BE BRUTALLY COLD.

2. Students: DO YOUR HOMEWORK or study for the test. Teachers: HAVE YOUR PLANS ready. Don't just throw caution to the wind because you want a snowday. This is not your classic lock of a snowstorm, it is a series of events which have to go the right way to turn in your favor. There is just as much of a chance you are disappointed.

3. Decide if you are a "Pumped Up Powderhound" or "A Nervous Nellie" and then consider what the other side has to say on the debate section below. If you end up going to school or work tomorrow, and there's no delay, the Nellies won, and you'll know why that happened. On the other hand, if you see the little ticker tape on bottom of the TV screen with your school's name on it, then Hallelujah, and you'll know why that happened too.

The most current radar map shows that the front is crossing the Appalachians, but there is already moisture along the coastal plain. I am happy with the rain... in fact, just keep on rainin' baby. I like it, I like it, and you'll see why when you read the debate below. There probably will NOT be accumulations near 4" for anyone south of NYC, but please keep in mind the 2 most important factors here: CONDITION OF THE ROADS and TIMING OF THE SNOW. That is the kicker which I think will at least let you roll back over for an extra hour of sleep Monday morning. If that doesn't happen, I will invoke the "NO GROANING RULE."

NOTE TO NEW READERS: When storms threaten a certain area, focus of posts on this site shift away from the overall view to specific regions at risk for significant weather. I am a teacher by craft, so naturally the focus becomes “will we have school or not” but I also aim to provide worthwhile information to all readers, including travelers, business people, family and friends in affected areas.

SO HERE WE ARE, DAY OF THE STORM. It’s not really a “storm” but more a glorified front with supercold Arctic air behind it. Outside at 12:00 PM in Baltimore, the air was very still, there is a little drizzle, and the temp is nudging downward to 39 F. Doesn’t feel like anything big is going to happen, but soon enough, this front will blow through with a swiftness that will make you think it is a storm alright. In keeping with the objective, bipartisan focus of this site, I offer you reasons FOR and AGAINST the impending snowfall.

FIRST...A Pumped Up Powderhound’s (PUP’s) reasons FOR the forecast and schools being delayed or closed:

“We can’t wait to see the surprise on everyone’s faces when they discover snow on the ground tomorrow, and a delay or closing of schools to boot. Just read and weep you Nervous Nellies.”

1) The fog and frost this morning in central Maryland indicates low-level cold air is already saturated.

2) Sunday’s temps did not get as high as forecasted (TWC says 45, it’s barely 40 F) that means overnight cooling will begin sooner, allowing a changeover to snow earlier. The high liquid to water ratio means that .10 of rain could easily end up as 1-2 inches of snow or more.

3) With the air saturated at present, any rain or snow falling will not evaporate. Roads will be wet at arrival of the front. Temps will plunge quickly, allowing the slickness to glaze over into a very thin coating of ice. On top of the ice will be a light covering of snow. The National Weather Service has said “ice should not form due to warm ground temperatures.” This is deceptively dangerous to put the expectation in the mind of a commuter that they should not encounter any ice at all. Translation: My Dad's office in Paoli, PA will probably be closed because their criteria is 1/2" snow and a thin glaze of ice.

4) The Arctic front will arrive quickly, with winds of 20-30 mph and gusts above 40 mph. This will produce isolated power outages at a critical time when school officials are making the decision to delay or close. Baltimore area schools have had early dismissals this year for strong winds.

5) Morning air temperatures will be in the upper teens throughout the I-95 NE corridor. Wind chills will be near zero for most of the day. Highs will not crack 25 on Monday in DC and BAL, and not crack 20 in PHL and NYC. When elementary children are at the most risk from the weather is when it is most likely you’ll see a delay.

And finally, a PUP’s reason for sticking with the forecast… Combine all these factors together and have them all occurring in a short period of time (rapidly falling temps, strong winds, isolated power outages, deceptively slick roads, snow falling in the early morning hours) and… the realization that county officials will probably not waste too much road salt on such a “minor event” and you have the makings of at least a 2-hour delay. Roads suddenly become surprisingly slick, salt trucks did not make their rounds, and now the slick spots are covered with perhaps just an inch or two of snow. Now you see why powderhounds are pumped up for this, as am I.

SECOND...A Nervous Nellie’s (ANN’s) reasons AGAINST the forecast and schools being open and not delayed.

"Okay you powderhounds, you think you got it ALL figured out. Your perfect little plans will come together just at the right moment to let you sleep in tomorrow? Natta, no way, ain’t happenin’ and here’s why."

1) This supposed “storm” you keep talking about hasn’t EVEN FORMED YET. Another classic example of all those eager beaver forecasters who say ‘and this front will sweep down, and this moisture will rotate in, and the wraparound cold air will change it all to snow..and… and..’ You know what, it never happens as quickly as you think. In fact, most of the time, these lows that are FORECASTED to form simply don’t. All you’re left with is flurries, so deal with it.

2) Dude, the ground is above freezing. Can you say “math and science?” If you want school to be closed or delayed, all the snow in the world won’t do a thing unless the ground is already BELOW freezing when the snow reaches it. Not at freezing, but BELOW… like 30, 25, or so. Newsflash: Better do your homework tonight.

3) Yeah, yeah, the snow ratio bit. We’ve heard this before “the colder the air, the more snow you get.” La De Da De Da. However, professor, remember that cold air is also very dry at upper levels. Supposing your little snowstorm EVAPORATES before it reaches the ground, then how will you explain the 2-3” of partly cloudy, eh?

4) Storms From The West Don’t Bring Extra Rest. Remember that little ditty from last winter? When was the last time you had off school for a glorified COLD front? Come on, get a life, or at least go back to your day job.

5) Playing the “cold little kiddie card” won’t get you any sympathy. What do you think these kids are going to freeze solid in 20 degree weather? We think they know how to wear a jacket, we also think the superintendent is not that easily hoodwinked by a cold front either.

6) Besides, getting the kids to school is probably better than having them home. Just what parents need is for their kids to be running around in sub 20 degree weather with shorts and a t-shirt. Then they’re all sick and coughing and whiny come the holidays, hence the movie "Nightmare Before Christmas."

SO THERE YOU HAVE IT, BOTH SIDES OF THE FORECAST. I'm going to take a break from the weather, and do schoolwork now...just in case I do get some extra time tomorrow, Mrs. Foot and I can get stuff done around the house. And so my esteemed colleague Mrs. Evans, my department chair, doesn't think that all I do is weather forecasting all day. And to prevent Mrs. Foot from making me sleep outside in the brutal cold, because there is more to life than blogging the weather.

The next update later this evening right before bed... around 9:00 PM. See you then.

Saturday, December 18, 2004

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evening update:

Well now, interesting how things do change every now and then. Suddenly, the Baltimore NWS has decided that it really is going to snow after all. Forgive the smugness, but they're the ones being paid your tax dollars to figure this stuff out. I just do this for fun. But you should check out the latest NWS Winter Weather Advisory, which is a far cry from the pooh-poohing and down-playing of snow earlier this weekend and Friday.

To be totally up front with you, I completely understand why major forecast agencies (except Accuweather) took the "non-event" route up to this point. I understand the science behind their reasoning. And I will outline the reasons for and against my current prediction. The headline quote above could apply to either me or them, or all of us together. To be safe, you should plan to go to work or school as usual on Monday. If by chance, you wake up Monday morning, and the forecasters are saying, "Well, this situation really changed a lot overnight...." You can be pleasantly surprised, and know in advance why it happened, as I will explain below. Then again, I might be the one with egg on my face, and if so, oh well, life goes on, and there will be another storm to ponder over soon enough.

But just for a moment, consider the science behind my seemingly blind faith towards snowfall Sunday night. I cannot take full credit for this, as it is the product of my experience forecasting similar storms, my research into the computer models on the internet, and comparisons with forecasters at Accuweather. This can be considered a "Pumped Up Powderhound's" Reasons FOR the storm."

1) IT'S ALL ABOUT THE MATH. A massive Arctic blast will sweep to the coast tomorrow, bringing cold we haven't seen in about 5 years. Monday's highs from PHL north MAY NOT BREAK 20. I am not making this up. Highs from DC north to BAL may not break 25. Any snow occuring will be in this super cold Arctic air. This is why the 2003 Blizzard was so snowy. It was 18 F at 2PM in Philly on Sunday at height of the storm. The colder it is, the more snow you can squeeze out of the same portion of the atmosphere. SO JUST DO THE MATH... All the major cities in the I-95 corridor will have at least .10 liquid, but with a ratio of 1:30 due to the cold air, that translates into 3 inches on the low side. Folks, I have seen this before several times, I am telling you, this smells of a major forecast BUST for anyone who's written off this storm. My forecast can equally bust, so we are all even in this game right now.

2) NO LAW OF PHYSICS SAYS SNOW CAN'T FALL BEHIND A FRONT. True, you would be skeptical of a forecast which called for snow behind a fast moving Arctic front. Doesn't it make sense that the front would PUSH all the moisture out to sea, and behind it is just cold dry wind? The structure of this front produces a unique arrangement where precip is in back of the front. This happens because there is low level cold air on the ground right now where you live on the East Coast. The front moving east has to push that air out of the way, forcing it and the moisture associated with it, upward. The resulting upward motion tends to pull a little moisture off whatever water body is nearby, be it the Chesapeake, Delaware Bay or the ocean. Rapid condensation occurs, but in the few hours between all that, the Arctic front has SWEPT through underneath. The moisture FALLS through the much colder air on backside of the front, and what would have been a 1:10 ratio is now 1:30. What would have been big wet flakes becomes tiny little flakes, and you thought you'd get half an inch, turns into 3 inches or more. If that .10 somehow makes it up to .25, at 1:30, we're talking 7.5 inches for some lucky chap somewhere along the I-95 corridor from NYC to DC.

Accuweather has provided a good explanation of why this happens, so I quote from them:
You know that low level dense air has a tough time getting over the mountains for a few hours. This jams up air just west of and in the mountains and enhances precip. When it does, it rushes in creating a zone where precip weakens. That may be just east of the mountains, say the Piedmont. But further east, the warmth of the Atlantic and Chesapeake, the increased convergence from the pressures staying low over water and rising so fast in the area where the air is rushing in, and the "bounce" factor.. in other words what goes up, must come down. These factors all warrant concern that late Sunday night into Monday morning there is a 3-5 hour period of strong winds and moderate to heavy snow with rapidly falling temps right along I-95 in the Mid Atlantic.

The forecast I outlined Wednesday and Thursday remains the call. There is no change. Here's a summary:

Snowfall in Maryland from Sunday evening to Monday morning:
-Western counties: 2-4"
-Central counties: Frederick, Carroll, Howard: 2"
-Baltimore, Anne Arundel: 3"
-Harford, Cecil, eastern shore: 4"+

Snowfall in Pennsylvania / New Jersey from Sunday evening to Monday morning:
-Central PA: 1-2"
-Lancaster and Chester counties: 2"
-Delaware County: 3"
-Philadelphia County: 3-4" localized spots of 5"
-Western/Central Jersey: 3-6" and more closer to the coast

Sunday, I will do a brief wrapup of reasons for and against school being closed or delayed, this is the long-awaited "Pumped Up Powderhounds versus Nervous Nellies" debate. From that, you can decide if it is worth staying up late to see what happens, or just playing it safe and going to bed on time.

Friday, December 17, 2004

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- President Franklin Delano Roosevelt

Thank you to all the loyal, supportive readers out there. I enjoy putting the site together as much as I hope you enjoy reading it. I must admit this impeding weather situation is a bigger challenge for forecasters than they would like for the first eastern storm of the season. However, as the event gets closer, the NWS and Accuweather are doing a good job of keeping options on the table in the event the storm shifts in either direction. I fully understand why they are hedging... as it helps to keep hype down while holding everyone's attention at the same time.

The map below will help you understand why it seems I am stubbornly sticking with the forecast, because I am. But just for fun, I will also do a pros and cons summary called the "Powderhounds v. Nervous Nellies" debate. This outlines the reasons for and against this storm, and schools closing or remaining open, in a fun and open-minded way.

This is NOT a waffling, however, as the forecast explained in previous post stands:
(Accumulations by Monday 9 AM)
-Overall 2"+ in Frederick County, 3" in Baltimore County, 4" in Harford, 4-6" in PHL area.
-Higher amounts the farther north and east you go, lesser amounts west.

Now, let's consider the "latest" computer model run and see what it tells us...

The graphic on the left is the GFS 60 hour forecast for about 1AM Monday morning. The graphic on right is the 10 AM Saturday morning forecast. Herein lies the reason why I am sticking to my forecast the way I think the snow will stick when it begins to fall .

1. The Philadelphia and Baltimore NWS admitted earlier today in their discussions that the GFS (Global Forecast System) has been projecting these systems too far east, and then brings them back west with time. That little bluish blob on the right.. WAS NEVER expected to get as close to the coast as it has now done. It has been worrying forecasters all week that it would end up a surprise sideswipe storm for the immediate coast.

2. This means the GFS is showing an EASTWARD bias, indicating that it is predicting storms to be too far out to sea, with a general 50-100 mile error. Accuweather is the one that identified this error, and has adjusted their forecasts accordingly. You can also read evidence of this in your latest "Special Weather Statement" put out by the NWS. Thus, the computer has had to back track the bluish blob up there closer and closer to the coast with each 6 hour run.

3. The third and most critical piece for why I am sticking with my forecast is the continued appearance of the light precip on EAST side of the MD mountains late Sunday night. Notice the big elongated gap in precip between the East coast and the Appalachians. Normally when systems from the west have snow, the mountains squeeze out all the precip, and the coastal plain is left with nothing. Not this time. There appears to be ample dynamics to keep the snow falling in the I-95 corridor after the cold front has passed to our east.

THE CRITICAL COMBINATION OF THE NORTH TRENDING UPPER LEVEL JET STREAM RIGHT OVER THE CHESAPEAKE, (dashed lines) AND THE DELIVERY OF LOW-LEVEL COLD AIR MOVING SOUTH (solid lines) IS A CLASSIC SETUP FOR CONVECTIVE SNOW BURSTS. What this means is a lot of energy is being squeezed together in an already compacted, turbulent area of the atmosphere. The super cold air (-20 C at upper levels), is going to wring out every last drop of precip. That's why the green blob is located where it is... in the zone of greatest enhancement. If there is a 50-100 mile eastward bias in the models, (God forbid, and Marty Bass take note), then move that green blob in the left graphic over just a tad, enhance it with Chesapeake moisture, and PRESTO! you have a surprise 4-5" when everyone else said flurries. One way or another, someone will have egg on their face for breakfast Monday, and someone will have cake. If we get a snowday out of this, I hope to have my cake and eat it too.

There is more to be said, as I think you will find the "Powderhounds v. Nervous Nellies" debate to be a fun read. But Jayla's grandparents are coming Saturday, and I have to help Mrs. Foot get the house ready, I can't just sit here and blog all night or that cake will be quite cold as I'll be eating it outside. :-)

I do have a few microscopic tweaks to the "Hourly Estimates" that I will post later when I get a chance.
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Note to hungry powderhounds: If you want current details on the Solstice Snowstorm, scroll down to the end of this post for the "Hourly Estimates" on specific details of snowfall rates and accumulations.

Note to nervous nellies: I know you are uneasy about this forecast because the Weather Service, Weather Channel and everyone else keeps changing their forecast. I am not going to change my forecast based on every whisper in the wind. The forecast stands, and if I am wrong, I will freely admit why and move on to the next storm.

This map is the projected "Mean Sea Level Pressure" (MSLP), Precipitation and upper level air currents for the period 1 PM to 6PM Monday. This data is put out by the National Weather Service and reorganized into a readable format by the Accuweather.com Professional site. This information is from a program called the "GFS" (Global Forecast System) and is one of the primary computer models the pros use when they talk about "our latest computer models indicate...." Forecasters all over the U.S. utilize this model as one of their sources, whether it is Norm Lewis, Marty Bass, Dave Roberts, Glenn Hurricane Schwartz, Al Roker or Foot's Forecast.

A simple key will help you understand what it means:

The Blue Line: The "540 thickness line" is an indication of how compressed the upper atmosphere is, as well as a general indicator of the ever famous "rain/snow line." As a general rule of thumb, any precip inside the blue line is mostly snow. Precip near the line would be snow/sleet mixed, and precip close to the line is rain/snow mixed. As you can see, the entire I-95 corridor is well inside the blue line, which is located way offshore by 1 PM Monday.

The Colors: Precipitation over a 6 hour period. Remember that the liquid to snow ratio is usually 1:10. The widespread yellow is a trace up to 1/10th of 1 inch. For snow, that translates into mostly flurries or in a very cold air mass, light snow. The green is .10 to .25 (up to 1/4 inch liquid precip). That translates into 1.0-2.5 inches snow. The purple inside the green is 2.5 to .5 (1/4 to 1/2 inch liquid precip). Now we are talking noticeable accumulating snow of 2.5 to 5 inches. You get the idea by now and reading the chart below, you can see that the brighter colors translate into higher precip amounts.

The Solid Lines: These are lines of equal surface air pressure, measured in isobars. Air/wind will generally move about parallel with those lines. Around a low the air moves counterclockwise, and the isobars over all of the northeast are all running north to south. That means a direct discharge of stiff northerly winds and very cold winds blowing straight south behind the storm from eastern Canada to North Carolina. The closer together the lines, the stronger the wind will be.

The Dashed Lines: These are upper air current indicators. When they are bowed south like you see, it means upper air trough of low pressure, and generally cold air. When the dashed lines have lots of space between them and are arched north, it means upper air ridge and generally warm weather.

NOW YOU HAVE THE SAME TOOLS AS THE PROS, and the forecaster of this site.
What can reading this map tell you about the likely weather for Sunday night into Monday?

1. Snowfall for the DC-Baltimore area on west and northwest will not be significant.
Overall: 2" in Frederick County, 3" in Baltimore County, 4" in Harford County and more as you head north and east. Earlier maps showed large areas of green in central MD, southeast PA, indicating 2.5" to 5.0" hence the reason the general snow forecast for central MD is 2-5"

2. Philly, New Jersey and New England will get the bulk of the snow, as you see the storm rotating north. Those areas might end up with 4-6 inches under this arrangement. Central PA from Williamsport on south and west (including State College, Altoona, Pittsburgh) will not see direct accumulations from this storm above 3 inches, but lake effect could easily push that total higher in the aftermath Monday night-Tuesday.

3. Daytime temperatures on Monday will be plenty cold for snow, so it will be powdery and not wet. Cold air will rush in behind the storm, blowing the snow around quite a bit.


Hourly estimates of weather conditions for I-95 corridor from DC to NYC and Central MD/PA.

12 PM Cloudy, breezy, a passing flurry and light rain mixed.
6 PM Overcast, light rain snow in western MD and PA
9 PM Overcast, flurries and intermittent light snow in central MD / PA

12 AM Light rain and flurries give way to light snow in central MD and eastern PA
2 AM Snow becomes light to moderate

4 AM Light to moderate snow continues...2 or more inches in most areas
6 AM Moderate snow with a few brief squalls through the area as coastal low moves north...2-3" on ground. North winds increase, blowing the snow around.
9 AM Moderate snow. South of PA/MD line, 3" on the ground. North and east: 4-5"
12 PM Tapering from moderate back to light. Very windy and cold, highs upper 20's
3 PM Light snow and then flurries with increasing north winds as low moves toward New England.
6 PM Accumulations: Another .5 to 1" in central MD to an area average of 4" between DC and PA/MD line.
Western MD/PA...2-3 inches, more in higher elevations due to lake effect snow.
Central PA...2 inches as bulk of storm passes to east. By this time, New England has begun to bear full force of storm, where accumulations north and east of NYC could top 12 inches.

Cooler and windy behind the storm, temps in the 30's PA and 40's MD/VA.

This is a slight tweak from the Thursday post.

Metro Baltimore and DC: Rain changing to snow Sunday, and falling temps overnight Sunday. Nervous nellies take note...with an on-going snow event early Monday morning, then yes, schools will start with a 2-hour delay, then re-evaluate at 6:30. Plows will have ample time to clear the snow as comes to an end Monday afternoon, thus schools will be OPEN on Tuesday 12-21, no delay.

Philadelphia and suburbs (Chester, Delaware, Montgomery): The farther north and east, the heavier accumulations are anticipated. With a potential of 4-6", I expect all PHL public and parochial schools will go with a 2-hour delay, as well as most suburban schools. Very wind and very cold. Highs in the upper 20's Monday and Tuesday. Yes that's you T/E and Great Valley. More likely that New Jersey schools will be closed.

Central PA: A delay is not likely as bulk of snow is to your east.

New York City: Delays are likely, but it takes at least 6” to close all NYC schools. But this is a powdery snow, not wet. Winds whipping through the cavernous city will create temporary whiteout conditions.

Boston: Rain at first, then change over to snow as storm lifts north and axis tilts westward. More likely you'll miss school on Tuesday.

Interior New York and New England: You're used to big snow, so fuggetaboutit. Although it will be bitterly cold with highs in the teens and wind chills well below zero.


If you only want weather details, look above. If you are new to this site and want some verification of it's accuracy and reliability, the post below aims to explain how the site operates, with some humor thrown in for good measure. As the winter storm season arrives, there is likely to be an increase in the number of people asking: “What is the address of that forecast website?” So new viewers should understand what this site IS and IS NOT.

Foot's Forecast....IS NOT a “Wishcast" site where the forecast is based on what I want to happen. It also IS NOT designed to criticize or support the decisions of any government or school agency on whether or not they should or should not have opened or closed their facilities based on inclement weather.

Foot's Forecast IS designed to give public viewers the opportunity to see the science behind weather forecasting, as well as compete with professional forecasters on the outcome of predicted events. Large scale organizations such as the NWS and Weather Channel will not make specific predictions about a certain area far in advance, that is not their role. This site however, utilizes the very same upper air and observation data as the big agencies, and makes a call based on experience with past weather patterns and a knowledge of how the atmosphere behaves under certain conditions.

If large scale computer models project a .25 to .5 equivalent amount of liquid in the atmosphere at a certain time, and the upper level temperatures are such that snow is the likely type of precipitation, then the call is made for a 2 inch to 5 inch snowfall. That is how I arrive at a snowfall prediction days before the other guys. But then you ask:


In becoming interested with a weather forecast which calls for snow, some people inadvertently fall victim to PRE-STORM PARANOIA. The symptoms are:

1. You start thinking about and making all kinds of plans for what wonderful things you will be able to get done on a particular day in the future because the forecast indicates your school or place of business might close for inclement weather.

2. You start to tell your spouse or significant other about all your wonderful plans for what you think you’ll be able to get done on this particular day in the very near future.

3. You begin altering pre-established plans for the time period immediately before and after the supposed inclement weather event. (Well, that meeting we had planned for Monday... you know, I mean it's looking like the weather will be....)

AND… the most significant symptom of PRE STORM PARANOIA

4. You begin checking the online weather forecast for the particular day in question, at least 5 times a day, seeing if you can find out “the latest.”

THE PURPOSE OF THIS QUEST IS: You are, quite consciously, trying to find meteorological justification for continuing your high expectations that the vast, complex, highly inter-connected, world-wide atmospheric thermodynamics will all cooperate in just the right order to enable you to allow your special plans to come true: Such as decorate the tree, catch up on grading or assignments, shop for presents, get the oil changed, shovel the walk, walk the dog, and sleep in, all on the same day.

AND THEN THE FORECAST CHANGES. So in your multi-hour checking of the Weather Channel, or Accuweather, or the Weather Service, or even Foot’s Forecast, you discover that the forecast changes slightly about every 6 hours. And with the forecast change comes a wide range of rollercoaster type emotions, usually correlated to the predicted amount of snow to fall. In the morning, the forecast calls for snow and wind, then by noon, it has changed to flurries. By dinner, you notice with horror that it just calls for cloudy and windy. Then the next morning, the storm is back and the forecast is for more snow than you hoped, then it’s gone again by the next evening. AND YOU WONDER… “Why does it keep changing like that?”

The medium and long term forecasts you read on the Weather Channel, NWS, Accuweather are mostly determined by an automatic computer reporting feature. In Washington, DC at the National Meteorological Center (NMC), vastly complex computer programs collect observation data from all over the world every second of the day. Every 12 hours, the computer then processes all that data into a program called the Global Forecast System (GFS). A “new run” of the GFS computer modeling program is conducted every 6 hours. The short term (1-7 day runs) occur first, followed by the 8-14 day runs, which occur 6 hours later. Thus forecasters all over the world get “the latest” scoop on what the computer sees coming down the road. There are a variety of other forecast models, run by different agencies, such as the European, the UKMET, The Air Force has one, so does the Navy, and so on.

The problem is that the information from the GFS is often automatically spewed right out to public sites, such as the Weather Channel local forecast. And you, the public viewer, end up seeing the forecast vacillate back and forth between rain or snow or wind or flurries, or no storm at all, all in the same day.


The forecast on this site is designed to digest all the various data sources, and synthesize it all into one precise statement that answers the question people want to know: “WHAT WILL HAPPEN WHEN, AND WHERE, AND HOW MUCH.” While I will admit when my forecast was wrong, I update the projections less frequently because it is not necessary to change it every 3 hours just because the computer said so.

So the nickname for this site has been: "The Final Word in Weather"

If the call for our first storm does not come true, I will explain why it didn’t, and see you on Monday. If it does come true, you can roll over to the cool side of the pillow, and dream some more about everything you’ll be getting done on “that particular day” you’re so worried about. Let's all hope that dream comes true.

NEXT UPDATE: A weekend overview Friday evening. Updates on the weekend will be mid-morning, mid afternoon and late evening. And be sure to check back in Sunday evening as we all watch and see what really happens.

Thursday, December 16, 2004

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Now this is what we mean by a real winter kickoff...


Computer models have aligned on the likelihood of the first major East Coast storm to develop along the VA/NC border Sunday afternoon. A fresh recharge of Arctic air will be moving toward the Northeast as the storm develops. This new supply of air will enable our anticipated storm to deepen rather quickly Sunday night, and allow for windy and snowy conditions from eastern Virginia northward to Maine. Compared to similar arrangements in previous winter patterns such as the one we're in now, this has the potential to become a SUPERSTORM much like the March 1993 Storm of the Century, but it's overall impacts will be limited to the Mid-Atlantic and New England. More later about why that is possible.

Foot's Forecast makes this call for the following total storm accumulations:
This is based on a detailed analysis of the 1:15 water-to-snow ratios expected due to cold air filtering into the storm overnight Sunday into Monday. Remember all you Earth Science folk out there... 1 inch of liquid is 10 inches of snow at 30 degrees, the colder the upper air temp, the more snow you can squeeze out of the same portion of the atmosphere

2-5" in the DC-Baltimore Metro regions for Sunday night into Monday.
4-8” in Central PA and Western MD mountains due to influence of lake effect snow
4-8” in southeastern Pennsylvania from the Philly suburbs northeast to NYC.
6-12” in NYC suburbs and interior New England

(this might be an underestimate if what forecasters are thinking about this storm comes true)

Accuweather forecasters are saying on restricted public access sites (which I pay to view) that most computer models have come into agreement on this developing storm situation, and have already begun to advise their major corporate clients across the East Coast on planning ahead for the resulting cold and snow.

So you Powderhounds, rejoice. And with the arrival of this system on the eve of the change in seasons, I predict it will become known as the "Winter Solstice Snowstorm of 2004." This event does have the potential to evolve into a Superstorm later in it's lifespan, but NOT for the DC-Baltimore region, as snowfall will be limited south of Philly because the storm is projected to develop along the Virginia coast and then move north. That means New England will get eventually clobbered, while everyone from DC north and east gets maybe isolated pockets of 6 inches, with an overall 2-5" spread.


Metro Baltimore and DC: Rain changing to snow Sunday, and falling temps overnight Sunday, with a on-going snow event Monday morning 12-20 is enough to close schools. Plows will have ample time to clear the snow as comes to an end Monday afternoon, thus schools will be OPEN on Tuesday 12-21. Lingering flurries and light snow will dot the area into Tuesday.

Philadelphia and suburbs (Chester, Delaware, Montgomery): The farther north and east, the heavier accumulations are anticipated. With a potential of 6" or more, I expect all PHL public and parochial schools, as well as most suburban schools to close Monday 12-20, but reopen Tuesday. In some rural areas where total could exceed 8 inches in isolated spots, perhaps a 2-hour delay on Tuesday. Very wind and very cold. Highs in the 20's Tuesday.

Central PA: Probably a delay on Monday, depending on how quickly the lake snow machine kicks in and interacts with the eastern snow.

New York City: Delays are likely, but it takes a lot more than 6” to close all NYC schools.
But this is a powdery snow, not wet. Winds whipping through the cavernous city will create temporary whiteout conditions.

Boston: Rain at first, then change over to snow as storm lifts north and axis tilts westward. More likely you'll miss school on Tuesday.

Interior New York and New England: You're used to big snow, so fuggetaboutit. Although it will be bitterly cold with highs in the teens and wind chills well below zero.


The timing of the snowfall is critical when considering if schools would be closed. In the Baltimore and DC metro region on Sunday afternoon, rain and snow will wet the ground. Slightly warmer conditions Friday and Saturday will have allowed the atmosphere to moisten a bit before the storm arrives. So as pointed out by my astute colleague Mr. Henry, it will not take as long for the “column to get saturated” which is a requirement for the snow to reach the ground.
If upper air levels already have a high relative humidity, it wont' take much for the air to reach saturation at cloud level. Factor in some evaporative cooling, which is an effect that cools the atmosphere as moisture converts to snow, and surface layer temps begin“falling with the snow.”

When overnight surface temps fall into the upper 20's...icy road conditions will result. On top of that slight ice layer will be another 2-3" of snow by Monday morning, and snow will continue to fall through the morning. This presents an unsalvageable situation for school officials, as a decision on whether to keep a 2-hour delay in place or change to closing would have to be made at approximately 6:45 AM. It will likely still be snowing at a moderate pace by then, which seals the deal for all those out there in schoolhouseland.

Combine all this with another surge of Arctic air behind the storm thanks to the counter-clockwise wraparound effect, and it will be a wind-whipped, snowy, Christmasy kinda time for everyone.And there's another one in the offing for Thursday-Friday, and this will spell White Christmas for much of the eastern half of the U.S. And behind that is even more cold and snow that will make this little clipper look like a flurry. It's beginning to look a lot like winter, finally.

During developing storm events, this site is updated around 6AM daily, then again at 6PM. Once we get into official storm mode (Watches and Warnings issued by NWS) updates occur at 6AM, 4PM and 9PM. The next regular update will be at 9pm Thursday.

Tuesday, December 14, 2004

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Here's a little advance tidbit for early next week. Check out the map below and compare this snowfall projection to the one a couple posts ago... it was a forecast for 8 AM Wed 12/22. This is for 8PM Monday 12/20. Although the accumulations look weak, you cannot put a lot of stock in the amount. The important thing to note is that 2 weeks ago, computer models were hinting at something a few days prior to Chrismas. Now a week later, the same time frame is still being alluded to.

The indication is that upper level systems are beginning to line up in the right sequence, and with plenty of cold air in place at the surface, we could be looking at our first shot at accumulating snow early next week.

There is also some consternation about what might happen late this weekend. I notice the Weather Channel now has "Rain and Snow Showers" for Sunday. While this probably will not end up being a big surprise storm, it does bear watching as it could surprise church goers on Sunday morning.

Monday, December 13, 2004

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And since we've no place to go, there ain't snow, there ain't snow, there ain't snow.

I know, not the kind of ending you were expecting to that song. I continue to search the crystal ball of future forecasting, and all I am getting is a cold reception. Although the first real arctic front is going to sweep through the northeast today, all we along the I-95 corridor will get is a brief burst of scattered snow showers... enough to tease and annoy, but nothing more.

This front will deliver the first real taste of winter cold, and it is going to stay for a while. Highs Wednesday 12/15 will not reach 40 anywhere from DC north. The map below shows the coldest Christmas Eve on tap in many years. While I still believe snow will be on the ground Christmas Day, the real big storms are looking to hold off until after Santa completes his rounds.

There is a little hint of something which might slightly whiten the ground this coming weekend...
Dec 17-19, but don't get your hopes up too much.

This pattern is one of three that I use to describe the kick off into winter. The first type is the 'Storm Rush'... which takes you from a normal pattern right into a rush of storms, dropping a bit of snow along the way, examples are Decembers in 1986, 2002 and 2003. The second type is the 'Umbrella' pattern, which scares everyone with way above normal temps for many weeks, then comes crashing back down with a lots of snow at the end of December. Dec 2001 was a prime example, with almost no snow even into New England until just before Christmas. Then the rest of the winter was very cold and snowy.

Then there is the third type... the "End Game" pattern, which starts off with a gradual step down to colder weather, very little rain or snow. This arrangement puts plenty of cold air in place, teases everyone with rumors of storms, and then WHAMO... the pattern goes out with a big winter storm at the end. Prime example is Dec 63-Jan 64, cold to start, no storms until the Mid Atlantic Blizzard of Jan 11-12, 1964. So patience my friend, we'll get snow eventually.


El Nino is on our side, as this year's reading so far show a weak to moderate El Nino. That's a slight warming of Pacific currents along the equator from Mexico west. This year, water temps are running .6 to 1.0 degrees C above normal. Looking at historical records for 10 previous winters where El Nino was rated at weak to moderate, in 8 of those 10 winters, something big happened. Something very big. In fact, those 8 example winters (57-58, 63-64, 76-77, 77-78, 85-86, 92-93, 00-01, 02-03) all produced "SuperStorms" which blanketed large areas of the northeast and midwest with big time snow.

Those with long memories remember the super arctic cold of 76-78, the 78 blizzards, and who can forget the March 93 Storm of the Century, or the I-95 Big Kahuna of February 2003.

So the morale of this story is that winters which seem to take their sweet old time getting the snow machine going... usually deliver whopping storms of historical porportions. I just hope it won't take until late January or February to arrive.

Next update later this week.

Thursday, December 9, 2004

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I know you might be skeptical of this ominous cold blast that has been promised for weeks now... but paybacks are coming. While interior PA may get some wet snow out of the Friday system, and a brief flurry in MD on the backside Saturday, this is the beginning of the winter pattern. And cold it will get. The map below indicates 8 AM temps for next Wednesday. Notice how far south the 32 F line goes, and the massive area in eastern half of U.S. with sub 23 F temps. You realize that means overnight lows may be in the low 20's to upper teens for that entire area. So winter is going to strike back big time next week. Get ready.

Wednesday, December 8, 2004

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Yes, I agree that winter is taking a while to make it's entrance. Wednesday and Thursday will make it seem that Global Warming is here to stay, but this is a necessary bump on the road if you want a long duration severe outbreak of cold and snow.

The later that the weather stays warm, the longer and more brutal the cold will eventually be.


Phase 1: The Warm Spell

Wed- Highs in low 60's throughout NE corridor from DC to PHL. Windy. 50's in upstate PA.
Thu- Less windy, abundant sunshine, highs around 60, low 50's upstate PA.
Fri- The first "transition" storm of the eventual winter pattern moves in from the Tennessee Valley. Rain for east coast by late in the day. Highs in low 50's.

Phase 2: Back Door Cold Front

Sat- Storm moves into New York, with rain along coast in AM, and snow/rain mixed turning to snow from Central PA west to Michigan, and scattered accumulations in the mountains down to Tenn/NC. Random areas of West VA to southcentral PA will see up to 2 or so inches of randon
accumulation once lake effect kicks in. Much colder air to follow with highs in 30's, lows in 20's.
Ski resorts begin making snow.

Sun- Brisk NW winds behind cold front will drive the lake snow machine, with flurries and light snow from central NY south to State College and West VA. Highs in 40's along coast, 30's in mountains.

Phase 3: The Invasion Begins

Mon- Another weak system passing to the north will unlock the final barrier between us and the Arctic air. "Cross polar flow" will begin to establish itself with a series of upper air systems that are lining up to allow direct discharge of brutally cold Siberian air to travel across pole and unload in eastern United States. (This is the upper air setup beginning on Monday, we won't feel it at surface until about Wed or Thu).

Tue- The recent warmth will make it seem like Tue's high of 42 in Baltimore is frigid. Welcome to my world... as overnight lows henceforth into the foreseeable future will not break 30.

Wed- Prepare for progressively colder and colder with each passing day. High 40, low 20.

Phase 4: A look ahead

Next weekend: Snow and ice is possible at some point next Fri-Sun
The week after: Unbelieveably cold air to make the week leading up to Christmas seem like it was designed especially for Dickens. Hence the saying, "Cold as the Dickens." All courtesy of the Polar Express from Siberia. In PA... highs in 20's lows in single digits. In MD/VA.. 30/10.

Snow days? Yes, I maintain that there will be one snow day before Christmas for all you in schoolhouse land.

White Christmas? Yes, quite likely that much of the country from Georgia north and east will have snow on the ground Dec 25th.

Enjoy! Next update this weekend sometime when we start to see evidence of this unfolding.

Tuesday, December 7, 2004

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I know you are well-trained to be skeptical of long range computer model projections. But just for a moment, isn't it fun to dream that maybe everything will be coming up roses for those of us who would love to see snow and lots of it for Christmas?

This week will feel nothing like winter or December, with daytime highs on Thursday flirting above 60 for the I-95 corridor, and mid 50's in interior Pennsylvania. But do not be hoodwinked by this mini-heat wave... because Tom Hanks is not far behind with a fully loaded Polar Express ready to charge south.

There is still the possibility that our weekend storms on Saturday will end as snow, but after the 13th, most of the nation east of the Mississippi will plunge into a super deep freeze that may make maps like the one above a strong possibility heading into Christmas.

Comparisons for the old timers? Remember 89... the year with snow at Thanksgiving, then the bitterly cold December to follow. Or how about Xmas 83, when it was 0 degrees for a high at my house in Philadelphia, or maybe the infamously cold winters of 76-77 and 63-64? All those Decembers started out warm, and then dove off the deep end. So get ready to go swimming.

Sunday, December 5, 2004

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Inflow of Pacific heat and moisture from recurving Typhoon will douse hopes of eastern powderhounds, for a few more days.

Unforunately, I will have to back off the earlier claim of the first big snowstorm this coming Friday, December 10. While it originally looked as though the elements were falling into place, this is not in the cards right now due to the influence of the typhoon which recently hit Taiwan.

The combination of a high pressure ridge off the Southeast coast, the Alaskan Low, and a high pressure ridge developing over S. California will keep a strong westerly flow of Pacific moisture into the western 2/3rd of the country until Friday.

That means what would have been snow on Friday is being replaced with highs which may approach 60 starting on Wednesday. But silver lining is that the warmer it is now, the much colder it will be later... so be patient, help is on the way. It does appear the tide will shift significantly in favor of powderhounds by Saturday and Sunday.

While we will have abundant sunshine and blue skies Wed and Thu, by Saturday night, there may be scattered snow showers and Sunday AM temps in the 20's. That will be the start of a very long period of dramatically colder weather and a parade of flirtatious storms.

It is going to be a changeable situation until we settle into a definite winter pattern. So check here first if you want the final word in weather.

Friday, December 3, 2004

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"It happened before, it will happen again. It's just a question of when."
- Charleton Heston, in opening voiceover of the movie Armaggedon


Indications are that by late next week, an I-95 special may be on the menu, with generous portions to go around for everyone else, including the interior Appalachians from West Virginia to central New York and New England. I am officially making the call that this is going to be the first real accumulating snow of the season for the big cities... from DC to NYC.

We know that the longer warm air lingers, the more severe the next cold outbreak will be. Arctic air that has been building up in eastern and central Canada will begin to spill southward by Wed 12/8 or Thu 12/9.

And not to be outdone by advancing Old Man Winter, Tiffany Tropics has delivered yet another tropical storm on the very last day of the hurricane season… Otto. He is spinning 800 some miles east of Bermuda, with winds of 45 mph. So there you have it… as one season draws to a close, the other is waiting to bust out of the gates.


While the Weather Channel and Accuweather public sites appear to trending away from snow this weekend for PA and MD, the NWS is moving back towards it. The cold front that swept through the northeast Wednesday delivered enough strong wind to knock out power to numerous schools in Baltimore County, giving those in schoolhouseland a 1-hour early closing. A minor upper-level system sweeping in behind the front may have enough moisture and surface instability to trigger some flurries or snow showers on Saturday for central PA.

While it is more likely these areas will only see flurries… this is an unusual system which has the potential to be a little stronger than anticipated. Upper-level short waves, as they are called, have the unique ability to deliver a brief, heavy dose of snow over a concentrated area. Although we currently do not have the cold air of early January… this same kind of thing happened Sunday, January 4, 2003. An upper level short wave arrived that morning, and moved a lot slower than forecast. Snow began that morning, and continued for about 6 hours, leaving 4 inches when all done. It was a total surprise to many forecasters, because there was no surface level system.

So you were warned here first… it may only be flurries, but if it turns out to be a lot more than that, you can say you knew all along.


I am trying to post a map that explains the situation graphically, but for now, here is the steps in the process. A few suggestions first...

- Get your radiator flushed and prepped for winter in the next 7-10 days.
- Stock up on your salt and ice-melter stuff before the rush. The public will be totally unaware of this storm until about Wednesday or Thursday of next week.
- Do whatever other winterizing techniques you do soon, because winter will arrive with a bang.

Steps in the process leading to our first big storm

1. A strong low pressure system will clip across the Great Lakes early next week, merge with another low coming up from the Gulf. These two will deliver a heavy rainstorm for the northeast on Tuesday 12/7, with another cold front that will blast to the coast on Tuesday like the one which just happened. So expect another round of pelting rain and then a blast of wind. I believe this system will end up being stronger than anticipated because of the rapid clash between the surging tropical moisture and the Arctic air moving south.

2. The Great Lakes Low will bring along an Arctic Front. The confluence of the low and the Arctic High will discharge bone shattering cold down the Great Plains and into the northeast. Overnight lows in the Lakes region will be in the single digits by next Wednesday. Highs in PA and MD will step down to the upper 30's and low 40's, with overnight lows in the low 20's. Delivering this cold air in advance of a storm system is key to any accumulating snow.

3. The cold front will trail from the departing low in eastern Canada all the way down to the gulf. This is a classic setup, because a lingering frontal boundary in the gulf creates instability, which eventually leads to development of a secondary low over Texas.

4. The final piece is an active southern subtropical jet. The arrangement of this jet stream is such that it has been consistently delivering warm moist air into developing gulf systems. Hence the strength of the front which just blasted through... it was enhanced by moist Gulf and Pacific air. By next Wednesday, the arctic front will have moved through, and intense cold air will be pouring south and southeast. The southern jet will send the gulf low from Texas/LA to Georgia to North Carolina to the Mid Atlantic coast by Friday morning, 12/10.

While computer models have been waffling back and forth on this for a couple days now, it is becoming clear in their overall trend that a major event is in store for the northeast next Friday and Saturday.

Thus, I believe the right pieces will be in right places to provide you with a rousing powdery kickoff to the winter season by the end of next week. If the clock and the storm communicate accordingly, we might even get enough snow for a day off school.

If this storm delivers accumulating snow, that will change the entire picture for the rest of December. Snowcover means overall cooler temperatures due to reflectivity of the snow, thus the resulting air mass left behind is colder. A second arctic front by the 15th should be the nail in the coffin for our warm trend, and send the eastern third of the country into a 10 day to 2 week cold wave that will last until Christmas.

The stage is set... so let's get ready to ruuummmmbbbbllee.

Tuesday, November 30, 2004

Thursday, November 25, 2004

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For all you powder hounds out there in snowland, Happy Days are almost here once again. Now before you flip out and go buy a truckload of salt, a quick explanation of the map above.

The color band at bottom is "Accumulated Snowcover" in inches over a 12 hour period.
This is the National Weather Service's GFS (Global Forecast System), which can project weather systems and their effects out 372 hours, or 15 days. The atmosphere has begun putting the pieces in place for a slow-at-first transition to winter starting after Thanksgiving, and then a swift plunge into the deep freeze by middle of the month.

The map above is an early indication that the first measureable snow for the Northeast U.S. may be in the December 4-5 time frame That date seems to be etched in the atmosphere's calendar, for it will be the third year in a row the I-95 corridor saw accumulating snow on or about December 5. The computer models continue to vacillate on whether this storm will be snow or rain, but it is clear a storm of some kind will be heading up the East coast during that time frame.

The only bad news at first glance is that if this minor storm plays out as indicated, it will occur on a Friday night into Sunday morning. That will automatically eliminate any chance for a bonafide "Snow Day" for any school district anywhere. The apparent snowfall looks to be in the 3-6 inch range for central VA, with 1-3 throughout the rest of the area.

The good news is that this far out in the computer models, a lot can change. If the cold we see coming from the 25th to the 5th is more entrenched than expected, perhaps the only worthwhile speculation would be that it is fair to say the computers "see" something snowy brewing for the Dec 4-5 period. It could mean that the eventual storm is stronger, or weaker than predicted. There is one clear signal this map is sending... the computer expects the cold air present at that time to be strong enough to send snow all the way to the VA coast and deep into North Carolina. That is a sign that many, many good days are ahead for those of us who yearn to see fluffy little flakes falling outside our window... only to roll back over, turn off the alarm clock and go back to sleep. (That is, if you're a teacher, and it is a weekday.)


I remain steadfast on the "snow first week of December" rule because I have seen this pattern before. Until the atmosphere makes a wholesale flip to winter, computer models are notorious for having difficulty picking up the minute indications that lead to the flip. Last year was a great example, and you see the same thinking reflected in all your NWS local forecasts for the next 10 days. Even 3 days prior to the 6 inch storm on Friday, Dec 5, 2003... all signs were rain and 45 to 50 degrees. Then on Monday, NWS caught on to the fact that the southern jet was active, and cold high pressure which had built up in Canada, was about to make a charge southward.

Friends, the same situation is setting up again. When we see a low pressure trough developing east of Hawaii, that tends to keep the subtropical jet active by sending moisture and systems across the Gulf of Mexico and into the southeast. This temporarily blocks the southeast movement of cold air, so in this early phase of transition to winter, you end up with snow in Chicago instead of DC. But as we move farther down the calendar, the high pressure ridge off the south Atlantic coast gets beaten down by the continual march of these clipper systems, dragging cold air behind them.

So the ingredients we need for an early to mid December kickoff snowstorm are:
- Active southern jet stream with a low pressure trough east of Hawaii (check)
- Above normal water temps in the Gulf (check)
- Large pool of cold high pressure parked over northern Canada (check)
- A series of southeast moving clippers to unlock the Canadian air (check)
- Weakening ridge off south Atlantic coast (getting there, not quite)

All these forces are setting the stage for what will become a whiplashing sprint from relative mild weather to overnight cold and snow.


This is based on the long term trends as shown by the Global Forecast models. The end game is this... the longer that Arctic air is blocked from entering the eastern U.S., the more likely that once it does make a move, it will stay entrenched for a period of 10 days to 2 weeks, starting around the middle of the month, with record-breaking cold and occasional storms with accumulating snow.

25-30 (Nov) Much colder, windy and dry, with a slow warm up at the end
1-5 Another round of alternating mild and cold, with occasional rain.
6-10 Mild with rain, leading to another shot of cold and windy weather, then snow by the 11th
11-24 Bone shattering onslaught of very cold air with several storms
25-31 Brief mild spell, to be followed by another record cold outbreak into the middle of Jan.

This trend will be closely monitored. You can be sure that you'll be the first to know of any signs
of a "breakout" in the pattern pointing to the first northeast snowstorm.

You have about 2 weeks to stock up on your salt and change your antifreeze.