Wednesday, December 7, 2005

THE FINAL WORD ON DECEMBER STORM # 2


(SUBTITLE: THE "ON AGAIN, OFF AGAIN SNOWSTORM")

FIRST GRAPHIC IS THE PROGRESSION OF ACCUWEATHER'S SNOW CALL OVER PAST THREE DAYS, SO YOU CAN SEE WHY YOU'VE BEEN GETTING WHIPLASH TRYING TO UNDERSTAND HOW MUCH SNOW IS SUPPOSED TO FALL.

Dec Storm 2A

SUMMARY: Winter Storm and Heavy Warnings blanket the Map from Ohio to New England, and all the elements seem to be in place for a quick hitting, fast moving Mid-Atlantic and Northeast Snowstorm. While this could end up a surprise 6-12" bonanza for the major cities, it may only come at the very last second and in the daybreak morning hours on Friday. Overall accumulations for most areas under currently under a warning will range closer to 6" than to 12". The snow will fall in a short time period, from midnight Thursday to 9AM Friday, and by afternoon, the sun should peek out before setting on a cold and snowy wind-swept landscape. Many schools will close as crews quickly discover how difficult it will be trying to keep up with snowfall rates of 1-2 inches per hour, and the morning commute on Friday will be very hazardous and nerve-wracking for those who have to venture out. Analysis follows below and snowfall accumulations to be posted this afternoon.


SECOND GRAPHIC PROVIDES A BIRDS-EYE VIEW OF WHAT IS GOING ON IN THE ATMOSPHERE TO GENERATE THE INGREDIENTS FOR OUR STORM

Dec 2B

WHAT FAVORS THIS STORM TO BE A BIG SNOW-MAKER:

1. Plenty of cold air in place. Lower than normal sea-surface temperatures off Mid-Atlantic coast helping to enhance and stabilize position of high.

2. Impressive southern jet stream tapping ample Gulf and Pacific moisture. Link.

3. Neutral NAO will allow storm to make a gradual East-Northeast jog as it moves toward coast, instead of bypass or get suppressed too far south. This kind of “slight ENE angling” is what we saw in the Feb 2003 blizzard and similar storms.

4. Fast moving storm will “moistent the column” overnight and by daybreak widespread heavy snow throughout region from Virginia to northern New Jersey, then moving toward NYC by mid morning and Boston by afternoon.

5. Terrible timing for Friday morning commuters…below freezing road surfaces given that snow will be falling in overnight hours means it sticks on contact, creating instantly slippery and hazardous conditions, as well as sharply reduced visibility for drivers in morning hours.

6. Perfect timing for students and teachers looking for a 3-day weekend. You can bet your boots this will close most schools from central and northern Virginia on north and east including the WV panhandle, central and eastern Maryland (Baltimore and DC Metros), Central, SE and Eastern Pennsylvania, the Philly Metro schools might be crazy enough to start with a 2-hour delay. NYC Schools will have a tougher call as snow is coming later in the day, they might end up with early dismissal.

7. Perfect timing for those who want Saturday to recover and dig out, as storm will be long gone by Friday evening, and sunshine and slightly warmer temps return Sat.

WHAT COULD PREVENT THIS STORM FROM BEING A BIG SNOW-MAKER:

Check the Baltimore/Washington NWS Forecast Discussion, they post a small list of criteria for your big time snowstorm, and sadly there are some elements in place to PREVENT this from being the storm you want it to be.

1. Placement of the High…is not to the North or West (as in the classic spot of southern Ontario or upstate New York. This kinds of High can drill a cold air damming situation in front of the storm. Granted we have cold air in place, but High is in the WRONG place.

2. There’ll be considerable mixing with and changeover to sleet/rain in southern parts of the storm, lower southern Maryland, eastern Virginia. This almost always robs a storm of energy which generally cuts down on snowfall for everyone.

3. Balt/DC NWS said it best…when there are multiple lows in play, this also reduces the likelihood of big snow because the energy required to concentrate on one big cyclogenesis is spread too thin among several systems.

4. Fast-moving storm will limit the amount of time it has to drop snow. That alone is going to knock a few inches of everyone’s 12 inch expectation.

5. Several low pressure systems have well over 1000 miles to cover between now and Friday morning, and must undergo a lot more transformation to become the blinding white snowmonster some are wishing. Granted you can see the moisture inflow from the Pacific and Gulf, but that moisture has to interact with the northern branch of the jet stream just right in order for those heavy snow warnings to materialize.

6. Low-level warming as a result of that return flow from the departing high I mentioned in earlier post. If we start to see southeast winds during the storm, this will first raise upper level temperatures, then surface, inducing a mix and changeover, which robs the storm of energy, cutting on accumulations for a large area. Also consider that snow-to-liquid ratios in the I-95 corridor will not be 20- or even 15-to-1 but more like 10-to-1, which means whatever the QPF (liquid equivalent forecast) is for your area, that's likely to translate pretty easily to the inches you'll see.

AFTER I RETURN FROM SETTING UP TODAY'S LESSON PLAN AT SCHOOL, I WILL POST MY ACCUMULATION FORECAST, AS WELL AS THE GRADE FROM LAST STORM.

36 comments:

Mr. Foot said...

A comment on a question from anonymous 21 yesterday, who asked whether NWS was saying 3-5 or 6-10. When I read the Winter Storm Warning Text, it says 3-6, yet my local NWS forecast has 3-5, then 3-5 again. I am leaning on a general 6 inches for most areas (most meaning MD, PA, VA because of deep moisture availability) and some localized spots might top out at 8 or 10. It seems NWS can't decide how much mixing will cut on snowfall accums, so they are going midrange. It would appear there is more than enough moisture to provide well over 3 for everyone, but not enough to get 10 for everyone given lower liquid ratios. Will be a fun storm to watch.... SNE I am looking into what will happen for you too.

Frank said...

Looks like here in CNJ I am hearing a lot of 3-6 and 4-8" amounts. They are mentioning mixing up here as well, that may cut down on totals. Seems like they are saying everything to make up for the bust call in the early week storm (even though they all act like they got it right)

Mr. Foot said...

Frank:
Better chance of mixing this time, especially early in the storm... then a period of snow and mix, then as storm departs, very likely ending as period of wind whipped snow.

Katie said...

Mr Foot, I have an activity scheduled for BCPS tonight at 7pm. Should I be worried about weather yet? Do you think the county will cancel evening activities?

Mr. Foot said...

There is no need to cancel evening activities as snow will begin after midnight. I am concerned there's going to be a BUST-O-RAMA for someone... there is huge separation between the two Lows, look on any radar to see what I mean. There is a GIANT dry slot that will take a lot of moistening to close. I also notice Accuweather continues to shift the band of heavy snow much farther north. There might be some big disappointment on the other side of this storm:

1. Totals in Northern VA/DC/BAL area due to sleet/freezing rain mixing could be below the 6" expected. I might have to say 4" for Dundalk instead of 6. School will still be closed due to icing, but not as much snow as we thought.

2. I wonder if all those heavy snow warnings in PA are overdone. I think a lot of that is going to get yanked back to just Winter Storm Warnings, or even just Snow Advisories. I notice NWS has also been trimming their totals all day.

3. The real winner might be as AccuWx has it...central/SE New England. How about this idea... the dry slot prevents the two storms from transferring, and areas predicted to get some snow get hardly any, and areas predicted to get a lot (6-10") get twice that.

I AM REALLY BOTHERED ABOUT THAT BIG DRY SLOT BUSTING A LOT OF 4CASTS INCLUDING MINE. I'll post again before bedtime...but not earlier than 10pm. Meantime, check the radars, that'll be the true indicator on what our storm is doing..not local on the 8's.

DerbsATerp said...

all of these differing predictions are making me wary of the forecasts.....i think i would be a good idea to have the paper ready for tommorow

kristine said...

Will someone please make up their minds??? I cant take the indecision anymore! :)

Frank said...

Kristine, you said it best. The forecasts are still pretty different at 10:25. Mostly hearing 3-6 though for central NJ. But only being a few hours before the main event, there is still a lot of indecision. I have a bad feeling it will be a bust for my area. Once they mention the word mixing, they are never wrong with that. I am thinking the 3" mark might be the right call, but here's hoping for the best!! :)

Mr.B said...

aporching 6" here in greencastle.

John said...

There is 3" here in Pikesville, MD

terpguy said...

0503-
Baltimore County Schools are Closed!

Mr.B said...

7" of snow but schools not closed yet but will have to be soon. "Roads covered"

NeedaSnowday said...

ICK.. here comes the freezing rain in Towson area!!

kristine said...

Heres to the first SNOW DAY!! Yahoo! Just be sure it clears up by tomorrow for my son's birthday party. Enjoy your day in the snow!!

Evan said...

In timonium the snow is gone and there is 3.25 inches of snow and a thin layer of ice in the middle of it.well at least there is no school today.

E.H. Boston said...

In Woburn, there is NO SCHOOL as well. Predictions between 6" and 9".

However, I am getting wary with this light SE wind that we are getting. When I woke up it was 23 deg. Now it is quickly approaching 30!

Needless to say, it is snowing very HEAVILY...accumulating about 2" since it started at 6:15 am. Later on this morning they are forecasting the snow to fall at the rate of 1-3"/hr. Wow! What a snowy day. Mr. Foot, you never put out your snowfall grade amounts. No cheating, just kidding.

Hoping for a lot of snow and a white Christmas.

Frank said...

Just about stopped here in CNJ. All schools are closed. We got 6" in about 6 hours. When I woke up at 7 visibility was about 1/4 mile, and snowing with giant flakes. Very cool to see. There was about a 15 minute period of light rain/sleet at the very end. We did receive the upper end of the 3-6" that was predicted, so I am very happy. The only bad thing is I had to take the drive into work on roads that were barely plowed!

Mr.B said...

7" in greencastle no school what a day. Now for the blowing snow with winds 20-30 with gust to 40mph. Temp at 33 maybe gettign up to 34.
Foot really looking forward to a post soon. What about next thursday and friday?

Lee said...

6" in Altoona (the northwestern observatory station). Shoveled up real nice, but the drifting is a pain.

Julee said...

What a BEAUTIFUL day! Not a LOT of snow, but due to the sleet and freezing rain, the hemlocks outside my window look as though someone threw a handful of diamonds on them! The tulip poplars are adorned with "cotton balls."
Hope everyone can enjoy something about this lovely snow day.

terpguy said...

Dear Julee-

Please call Liriodendron tulipifira the Tulip Tree, it is not a poplar, but a member of the magnolia family. Yeah, I know, some tree guides call it that...

Thanks for indulging an old f@rt Field Biology teacher his pet peeve.

Enjoy your day off!

TG

Julee said...

TerpDogg - I do INDEED know that the Tulip TREE is Liriodendron tulipifira. I used to be a trail guide at Oregon Ridge.
Just be happy that I didn't call it the "Tulip Popular" as one Baltimore County science teacher did while I was guiding his students through the woods.

Mea Culpa.

My tulipifiras are adorned with "cotton balls."
Okay, THAT sounds X-rated.

terpguy said...

Dear Julee-

Sorry..knee-jerk reflex. Still love me?

Anyway, I think they're "popular"..I have a bunch in my backyard.

Enjoy the beautiful whiteness!!

linda said...
This comment has been removed by a blog administrator.
linda said...

Well we got 6-7 inches up here in Bucks county. I don,t know what the official reading will be, but it sure looks beautiful. With the wind and wind gusts it really feel cold out there. I really like when we get snow starting early in the morning because I love to watch a storm in progress, maybe next time. Where have you been all day Mr Foot, I hope you and your family are just enjoying the snow.EH I'm with you, It would be wonderful to have a White Christmas. And I hope you snowstorm is progressing nicely.

Andy, Southern York County PA said...

Hair under 7 inches on my deck in York County this morning. Not bad at all! Looking forward to a possible storm next Thursday. Sure the forecast will change a 1000 times by then, but it's fun to follow the trend.

Nbcweatherman said...

Picked up 7" total here south of Altoona,PA. Drifting snow is a problem all area schools were closed today.

Mr. Foot said...

EH... I did technically issue my snowfall forecast when I said "most areas will be closer to 6" than 12" nudge, wink. :-)

But you are right I forgot (or never finished) the calls... so I'll post here what I emailed my faculty about the Balto metro area. I'm not going to give myself a blanket A..but I thought it worked out well that I said closer to 6" be the general rule.

Here's what I posted on email to my school at 12:00 Noon Thursday:

Quick moving, heavy hitting storm will drop 6-8 inches on the Baltimore Metro area in the overnight and early morning hours on Friday. Road surfaces are already at or below freezing due to recent cold, so any precip falling out of this storm will freeze on contact with sidewalks, roads, bridges when it occurs in overnight time period.
Dynamics of this storm will produce a variety of precip, including sleet and freezing rain early on, followed by bursts heavy snow, and quite possibly thunder and/or lightning for a few moments sometime between 3AM and 6AM. Snow may be falling at the rate of 2-3 inches an hour for a brief time, making travel very hazardous.

ACCUMULATIONS BY 9AM FRIDAY
Dundalk...6" with sleet. Towson...7"
Owings Mills...7"
Elliott City...5" with sleet Landsdowne/BWI area....4.5" +sleet Baltimore City...5" with sleet. Bel Air...7"
Aberdeen...5" with sleet. Southern PA...8"

I do have readers who originally saw this on their school email so they can vouch for the validity of this call. Without any objection I will grade the storm based on these numbers.

Mr. Foot said...

Sorry everyone I did not post earlier, was on the road with family Thursday night and getting two little ladies ready for travel is challenging.

Am looking ahead to the next pattern and will post on that soon before weekend is out.

DerbsATerp said...

here in college park we got a half day, and about 2 or 3 inches of this snow/ice/sleet mixture...most of it was melted by the time i got up ;)

E.H. Boston said...

Mr. Foot, I was just joking.

Finishing off a snowy day in Woburn...we finished the day off with just over 12" of snow.

About 4.5" of gloppy snow fell by 1PM and then it was all down hill. Frequent thunder and lightning was noticed and we had WHITE OUT CONDITIONS for 3 straight hours. It was unbelievable and we got 8" of snow in 2.5 to 3 hours. It was unbelievable. The snowbanks at the end of my driveway are 5-7 ft!

I think Boston officially received around 6", but I am not sure, and north and west of me some places received between 14-18" of snow. Craziness, when they were just calling for 5-9" this morning.

Mr. Foot, is this cold and stormy pattern sticking around or are we going to be getting a break?

Winter 05-06 is starting off great...Andy of York, Co., PA, you called it!

Julee said...

EH

You forGOT to remind me that I was going to move to BOSTON this winter!
WOW! What a start to your snowy season!
I had NO idea when the weather guys said that NE was getting a "pounding" that you were getting . . . a pounding!

Mr. Foot -- when are WE going to get a pounding? and what's this about ANOTHER storm on Thursday? Wild speculation or is there a real foundation for this? Too far away to comment on now?

E.H. Boston said...

Julee, move to Boston...

Woburn Snowfall So Far
October 29: 1.5"
Thanksgiving: T
November 27: T
December 4: 2.5"
December 9: 12.5"

SO FAR: 16.5"

Boston:
October 29: 1.1
December 4: 1.9"
December 9: 9" (Logan Airport)

SO FAR: 12.0"

Yeah, I have heard speculation about a storm Thursday and I have heard that it could be one that orginates out of the Gulf, again, however, this time, it may be an inland runner, which would bring RAIN to all of the major east coast cities. Not sure, but there could be another significant storm to deal with in about 5 or 6 days.

What a day!

Andy, Southern York County PA said...
This comment has been removed by a blog administrator.
Andy, Southern York County PA said...

For Karma purposes lets say it will be rain. Over the years every time they raise the snow flag we seem to get cheated a the last moment. Let's raise the rain flag and hope for the best. Some of the best storms were never forcasted to evolve the way they did. Actually, most storm never evolve exactly the way they are forecasted.

Mr. Foot said...

Good morning everyone... a crisp and beautiful 32 degrees in suburban Philadelphia at my parents. We are good at sitting around watching the children play on a Saturday morning, and otherwise doing nothing.

E.H...way to go dude! 12 inches, I am impressed. Of course I should expect nothing less for SNE.

Julee...do you need help packing?
Andy...I think your calls have been more on than mine for these storms.

Next weeks storm...I have read two reports that argue for either an Appalachian runner (rain for I-95..seems more likely) or a Nor-easter (snow for I-95...seems more like wishcasting). When I get home from the weekend trip, I will post on this developing situation slated for the Dec 14-15 time frame.

Enjoy the sunshine and fresh white blanket of snow.