One Year Later: Remembering the KU Boxing Day Blizzard HECS

[MJO812]

[Chris L]

As for the duration factor, this was quite a sight to see sheets of snow falling at 2-3" per hour, priceless for several hours.

[green tube]

here's the thread during the heart of the storm 2:30pm to nearly midnight, 10/26/10

http://www.americanwx.com/bb/index.php/topic/6360-nycphl-dec-26-27-boxing-day-blizzard-part-9/

[earthlight]

At this exact time last year the famous discussion between myself, baroclinic instability, and dsnowx occurred where we basically said the models had to trend 15 miles west with the shortwave over the Plains to make this storm happen. Here are some of the posts

Earthlight

Posted 24 December 2010 - 03:14 AM

The NAM took a huge step towards a more amplified solution at 06z thus far..everything looks better.

Earthlight

Posted 24 December 2010 - 03:18 AM

Literally gut wrenchingly close at 54 hours when you watch the interactions aloft.

Earthlight

Posted 24 December 2010 - 03:26 AM

Closed off at 60 hrs with an absolute powder keg at H5...nobody along the coast is out of the game yet.

baroclinic_instability

Posted 24 December 2010 - 03:38 AM

I am impressed with the end results. The NAM looked like garbage compared to the ideal 0z GFS and it still ends up close. If it had the exact same upper level height configuration, this would have been even more impressive than the 0Z GFS. NAM is also ridiculously unstable near the circulation, and convection going to play a huge role here.

And my favorite one of all

Earthlight

Posted 24 December 2010 - 03:39 AM

We're teetering on the edge here. If the guidance continues to trend stronger with the shortwave that amplifies into OK/KS and then essentially scoops up the shortwave on the Gulf Coast...we're going to see dramatic results. If not, we're going to see a dramatic trend backwards. GFS is an extreme outlier with the shortwave over OK/KS but if it comes in stronger, you can pretty much picture yourself lighting a match in a room filled with kerosene.

And then later this morning

Earthlight

Posted 24 December 2010 - 11:05 AM

it's a Christmas miracle :lmao:

[tmagan]

It wasn't until the 15Z SREF's came in later that day though that we knew the worm had turned.

[earthlight]

Probably one of the coolest moments I've ever experienced in forecasting/meteorology.

[earthlight]

This post was awesome too.

http://www.americanw...post__p__176910

That's enough reminiscing for tonight....just glanced at the 00z Euro..I'm off to bed to go drown in my tears in hopes that they will flood my area therefore altering the weather pattern and by some act of god causing high latitude ridging.

[tmagan]

http://www.americanw...post__p__176304

Probably one of the coolest moments I've ever experienced in forecasting/meteorology.

Amazing fact about that game: It was tape delayed a la 1980's NBA games.

[earthlight]

Amazing fact about that game: It was tape delayed a la 1980's NBA games.

Haha yeah that's a cool factoid I always tell people.

Man, it is almost sad to look back at this storm a year removed from it. Reason being.. I know that it is highly unlikely we will ever experience something like that again in our lives. I wish I could've let the whole thing sink in a little more.

[nzucker]

Haha yeah that's a cool factoid I always tell people.

Man, it is almost sad to look back at this storm a year removed from it. Reason being.. I know that it is highly unlikely we will ever experience something like that again in our lives. I wish I could've let the whole thing sink in a little more.

I said that after all the awesome storms of 09-10 and then 10-11 happened. Big storms are becoming more common so I'm sure we'll see another Boxing Day in the next few years, minus HPC initialization errors. Sure was surreal how that played out.

[NJwinter23]

I don't understand how whenever this storm is brought up, even in it's own memorial thread, a few people manage to downplay it and then make claims that the January 26-27th 2011 storm was somehow better/more impressive. I understand a lot of people got screwed in Boxing Day and got more snow in the Jan storms, but Boxing Day ranks light years ahead of the late Jan storm from every standpoint possible: snowfall-wise, cold, winds, Meteorologically, societal impact-wise...It really shouldnt be a discussion. and lets keep it on topic to appreciating how incredible this storm was. Just take a look at the last couple posts by Earthlight to appreciate how everything came together on this one.

http://www.erh.noaa....s/12262010.html

Snowfall reports from the 5 boros more 20+ inch reports than <20 by the way.

...BRONX COUNTY...

BEDFORD PARK 23.7 830 AM 12/27 PUBLIC

SOUNDVIEW PARK HOMES 22.5 800 AM 12/27 TRAINED SPOTTER

BRONX 20.9 1200 PM 12/27 PUBLIC - BRONX ZOO

WEST FARMS 20.5 1000 AM 12/27 PUBLIC

EASTCHESTER 20.0 925 AM 12/27 PUBLIC

RIVERDALE 19.4 840 AM 12/27 PUBLIC

PELHAM BAY 17.2 840 AM 12/27 PUBLIC

EAST TREMONT 16.0 800 AM 12/27 PUBLIC

PARKCHESTER 15.7 840 AM 12/27 TRAINED SPOTTER

...KINGS COUNTY...

BROOKLYN 24.5 800 AM 12/27 PUBLIC

MARINE PARK 24.5 800 AM 12/27 PUBLIC

SHEEPSHEAD BAY 24.0 700 AM 12/27 TRAINED SPOTTER

...NEW YORK COUNTY...

CENTRAL PARK 20.0 700 AM 12/27 CENTRAL PARK ZOO

...QUEENS COUNTY...

MIDDLE VILLAGE 21.5 1250 PM 12/27 PUBLIC

FLUSHING 21.0 207 PM 12/27 TRAINED SPOTTER

BAYSIDE 20.5 1200 PM 12/27 TRAINED SPOTTER

HOWARD BEACH 18.0 200 PM 12/27 TRAINED SPOTTER

RICHMOND HILL 18.0 1200 PM 12/27 TRAINED SPOTTER

ASTORIA 16.1 801 AM 12/27 PUBLIC

FRESH MEADOWS 16.0 1000 AM 12/27 PUBLIC

JFK AIRPORT 15.6 700 AM 12/27 FAA CONTRACT OBSERVER

LA GUARDIA AIRPORT 14.0 700 AM 12/27 FAA CONTRACT OBSERVER

WOODSIDE 14.0 645 AM 12/27 TRAINED SPOTTER

...RICHMOND COUNTY...

GREAT KILLS 29.0 900 AM 12/27 PUBLIC

WESTERLEIGH 26.0 500 AM 12/27 PUBLIC

ELTINGVILLE 22.0 800 AM 12/27 PUBLIC

STATEN ISLAND 17.8 800 AM 12/27 TRAINED SPOTTER

[NYCvort]

Incredible looking back at how different the GFS and ECMWF were at this point. At this time last year no one knew what to believe and to top it all off we had HPC claiming GFS model initialization errors. The GFS had the storm all wrapped up and a nice hit for us but the ECMWF still had mostly an open 500mb wave and a complete mess.

12z/24 GFS:

12z/24 ECMWF:

[CooL]

I have learned a lot since 1 year ago looking back. I thank this board for that!

Merry Xmas!

[NJwinter23]

I was out celebrating my birthday on the 23rd last year and arrived home Christmas Eve morning to pretty much a no-go on this storm...was very disappointed, and wrote up this article pretty much throwing in the towel...it was right as the 12z gfs was rolling out and the famous HPC bad initialization statements.

http://www.examiner.com/weather-in-newark/storm-on-sunday-looking-mostly-a-miss-to-the-east-light-snow-still-possible

"Over the past 2 days, we've seen a convergence on the computer models of a further east track of the storm on Sunday that would keep the heavy snow offshore. So It is looking like a significant snowstorm will not occur for us unfortunately, but will definitely continue to monitor the situation as it is not set in stone quite yet. We will watch for the short term model trends now to hopefully catch some of the fine details and/or any drastic trends should they occur. At the moment some light snow is definitely possible as the coastal storm comes up the coast Sunday PM, and any gradual/significant trends west could still yield an accumulating snow event.

As for Christmas Day, It will start out in the low-mid 20s when you're opening presents and be heading for a high near 35º with increasing clouds in the afternoon. If we're lucky, perhaps a few snow flurries or snow showers will be around on Christmas night to really top off a seasonable Christmas Day."

[earthlight]

My post from 4am after the storm ended

Things are rapidly ending here now..and the radar confirms it. I'm off for a few hours of sleep..and I will never sleep so happy. Just an unbelievable day.

Before I go I have to give one more shoutout to everybody in this thread. Just an absolutely incredible 5-7 days of discussion. This thread has improved ten-fold over the past few winters, and for everybody involved in this event you should really take it all in. This is a really historic event when you put it into perspective. People are going to come in with 30" reports...and two days ago this storm was modeled (by every model) to head 300 miles out to sea. Event's like these do not occur very often in the current day of technology we have in the field of meteorology. They talk about the surprise bust, or the surprise event...there's a reason these are so few and far between nowadays. The guidance we have is so good, that these are becoming exceedingly rare.

But for everybody who stayed up late each night, talking about the GEFS mean departures and the big block, everybody who spoke about the amplitude of the ridge axis and it's positioning over Boise, everybody who stayed up and watched the southern stream shortwave come onshore, everybody who was deflated as the heights were just a "hair" too deamplified on the east coast, everybody who watched the models dig a huge northern stream shortwave into the Plains and phase in the shortwave, everybody who literally couldn't believe what they were seeing on Christmas Eve and Christmas Day modeling as the GFS, Euro, GGEM, Uk, etc all came on board, and everybody who posted in this thread or added a single ounce of discussion, or learned something...this storm was for you...and I hope you all enjoyed every single flake of it. So thank you. I certainly enjoyed every moment of it.

And now for a long winters nap. Tons of shoveling to do in the morning. Totally worth it.

[Thunderdude]

Winds were so impressive with that storm aside from the heavy snows. There was isolated areas of thundersnow with this. That was probably the 2nd most impressive storm aside from the Blizzard of 96.Jan 27th event was wild too with many areas having thundersnow where in my area there was little of thundersleet/freezing rain. Snowfall rates were insane in both storms. I call the Jan 27 the "Thunderblizzard" with widespread thundersnow where it my area there was one flash of lightning followed by a rumble of thunder when the 2nd batch of heavy precip came and then turned back to snow within an hour. I had 14" with the Boxing Day Blizzard and 12" with the Jan 27th event. Amazing that winter had three KU's storms due to the amazing strong blocking and -NAO. That allow for the storms to take the right track and keep the cold air in place.

[earthlight]

I had thundersnow four or five times during the boxing day blizzard, i don't know how isolated it was. There were several reports in queens and jersey city as well.

[Weathergun]

I had thundersnow four or five times during the boxing day blizzard, i don't know how isolated it was. There were several reports in queens and jersey city as well.

I didn't hear thunder. But the winds were the strongest I've seen in any snowstorm.

[H2Otown_WX]

I didn't hear thunder. But the winds were the strongest I've seen in any snowstorm.

Yeah I agree, the winds with this were something to behold. It was a frustrating storm snow amount-wise here (man oh man did you NJ guys cash in), but the winds were like nothing I've ever experienced.

[Guest Pamela]

I measured 12" here during the 12/26-27/10 blizzard. I suspect some (not necessarily all) of the higher reports from LI might have come from eager young snowfreaks with the subconscious "if NYC got 20 inches I must be undermeasuring" attitude. Combine that with the fact the heavy drifting made the snowfall measurements somewhat of a judgement call, and I wouldn't have the self-doubts that you are having. You did your best at the time and it may be better than the next guys effort.

I remember feeling the same at the time about some nearby towns being higher, so I remeasured and remeasured but I just couldn't justify changing my total. You've got to go with your best effort, otherwise it's all make-believe. I am quite comfortable with my 12" snowfall measurement here; it's still eating at me that we didn't get more in that particular storm, but it is what it is.

After checking the liquid equivalents at the two closest stations to my north and south yesterday, I am a good deal more comfortable with the # I came up with for 12/26/10...

I'm located about midway between Islip (1.00") and Bridgeport (0.83")...so, in retrospect, maybe I did a good job....

[NJwinter23]

Wrote this during the evening of Xmas Eve..

http://www.examiner.com/weather-in-newark/unbelievable-trends-towards-a-major-snowstorm-with-tonights-model-runs

"I'm truly astonished at the developments tonight on the computer data which has all shifted DRASTICALLY towards a major snowstorm for the East coast which would begin late Christmas night for New Jersey. I'm almost hesitant to go all out on this update until tomorrow morning's models just because of how drastic this has been tonight and to get any sense of continuity. However, between the new model data and what I'm watching happen in real-time currently, I am just about sold on this. The key here is that a MAJOR adjustment, which would usually be very suspicious to me across one model cycle, has occured within 48 hours on the computers and I believe it is because they have FINALLY keyed in on the 2 major pieces to the puzzle that are about to phase together in the deep south to get this storm started in the Gulf of Mexico. Once this phase occurs, we will have a rapidly deepening coastal storm that looks like it will come up the East coast and cause major problems.

Tomorrow morning's model runs will be the final nail in the coffin on this one so I will wait until then. I will post an update around noon hopefully, which will include snow totals and the potential winds. Merry Christmas everybody."

[Guest Pamela]

Snowcover was the big story of the winter here. We had at least an inch on the ground from 12/27 - 2/28, double digits from 1/12 - 2/17, and 20" or more from 1/26 - 2/3.

Out here, the ground was well covered with snow 71 days for 2010-11; including 65 consecutive...12/26/2010 - 2/28/2011.

The only winter to exceed that since I moved here in December 1994 was the 2002-03 winter which had 72 days with the ground well covered with snow. Note that I did not keep "days with snow on the ground" until the last decade...so the total for 1995-96 will be forever unknown.

[Guest Pamela]

Here is how we got our 39.4" total for January in Smithtown:

1 0.0

2 0.0

3 0.0

4 0.0

5 0.0

6 T

7 2.4

8 0.1

9 0.2

10 0.0

11 1.8

12 14.0

13 0.0

14 0.0

15 T

16 0.0

17 T

18 1.2

19 0.0

20 T

21 4.0

22 0.0

23 0.0

24 0.0

25 1.1

26 6.0

27 8.5

28 0.1

29 0.0

30 0.0

31 0.0

I generally do not take measurements at midnight (unless we are going into a new month)...so my January 2011 totals are more or less event totals...I also do not record traces.

Jan 7: 2.5"

Jan 9: 0.5"

Jan 11-12: 18.0"

Jan 18: 0.8"

Jan 21: 3.8"

Jan 25: 2.0:

Jan 26-27: 14.0"

Jan 28: 0.1"

[Hailstorm]

12/24/2010 0z NAM comes in with much more favorable H5 conditions but still largely a miss.

12/24/2010 0z GFS delivers 0.50" of QPF for NYC while giving eastern LI about 1.00."

12/24/2010 0z UMKET edges the storm a bit west

12/24/2010 0z JMA shows a big hit.

12/24/2010 0z GGEM, MM5, Euro and GEFS still are big whiffs.

12/24/2010 HPC early morning discussion uses the models that do not give NYC a snowstorm:

TRIO OF SHORTWAVES PHASING INTO AN UPPER LOW ACROSS THE CENTRALAPPALACHIANS SUNDAY MORNING...LOW PRESSURE AREA STRENGTHENING OFFSHORE THE EASTCOAST...PREFERENCE FOR AN 18Z GFS/12Z ECMWF COMPROMISEINITIALLY...THE NAM HAS TRENDED SLOWER WITH THE SYSTEM MOVING OUTOF THE SOUTHWEST AND STRONGER WITH THE PIECE OF ENERGY MOVINGTHROUGH THE MIDWEST OVER ITS PAST DAY OF RUNS. ONSATURDAY/SUNDAY...THE NAM HAS TRENDED STRONGER ALOFT WITH THE MAINUPPER CENTER BUT BROADER OVERALL WITH THE TROUGH. THE NAM SURFACELOW LIES IN THE MIDDLE OF ITS PAST DAY OF RUNS TRACK-WISE...THOUGHIT IS FARTHER WEST THAN ITS 12Z OR 18Z RUNS. THE GFS HAS TRENDEDSOUTHWEST/SLOWER WITH THIS SYSTEM OVER ITS PAST DAY OF RUNS. THEECMWF HAS TRENDED QUICKER WITH THE SOUTHERN STREAM SHORTWAVE...BUTSTRONGER/FARTHER SOUTH/MORE PHASED WITH ENERGY MOVING THROUGH THEMIDWEST/ONTARIO/GREAT LAKES OVER ITS PAST COUPLE DAYS OF RUNS. THERE IS A LONG TERM MULTI-DAY WAVER SEEN IN THE ECMWF SURFACELOW...AS ITS SURFACE LOW HAS TRENDED QUICKER/WEAKER OVER ITS PASTCOUPLE DAYS OF RUNS...THOUGH IT IS SWINGING BACK TOWARDS ITSSOLUTION FROM SUNDAY.WITH THE SOUTHERN STREAM ENERGY...THE 12Z CANADIAN IN ON THE SLOWSIDE OF THE GUIDANCE AND ENDS UP WITH A CLOSED SYSTEM ALOFT LATESATURDAY IN THE GULF OF MEXICO. CONSIDERING THE FLOW UNDER THEBASE OF THE CONSOLIDATED UPPER LOW IN THE GREAT LAKES...A QUICKERSOLUTION SHOULD VERIFY BETTER...SO WILL RULE OUT THE 00Z CANADIAN. THE 00Z NAM HAS TWO CENTERS WITHIN THE MAIN UPPER CYCLONE EARLYMONDAY WHILE THE 18Z GFS/12Z ECMWF/18Z GEFS MEAN/12Z ECMWFENSEMBLE MEAN HAVE ONE CENTER OFFSHORE MAINE AT THAT TIME. OVERALL...THE 00Z GFS LOOKS TOO SLOW/SOUTHWEST WITH ITS CYCLONENEAR THE EAST COAST AS IT HAS THE SUPPORT OF ABOUT ONE-FIFTH OFTHE 18Z GEFS MEMBERS AND 1/30 OF THE 12Z GLOBAL ENSEMBLEGUIDANCE...SO IT COULD NOT BE USED HERE. THE 12Z UKMET HAS THESYSTEM OPEN AND MORE COASTAL ALOFT WHILE THE 12Z CANADIAN IS OPENBUT WEAKER WITH ANY ENERGY OFFSHORE NEW ENGLAND. AT THESURFACE...THE 12Z CANADIAN SWINGS THE LOW THE MOSTOFFSHORE...WHILE THE 00Z NAM/12Z UKMET SHOW AN INTERMEDIATESOLUTION...AND THE 18Z GFS/12Z ECMWF ARE THE FARTHEST WEST. BOTHTHE 18Z GEFS MEAN AND 12Z ECMWF ENSEMBLE MEAN FAVOR A MOREWESTERLY SOLUTION AT THE SURFACE AND SHOW GOOD AGREEMENT WITH THEGFS/ECMWF ALOFT...THOUGH THE MEANS ARE QUICKER THAN THE 18Z GFS. TO ACCOUNT FOR THE UNCERTAINTY...A COMPROMISE OF THE 18Z GFS/12ZECMWF WILL BE PREFERRED HERE WHICH SWINGS THE CYCLONE JUSTSOUTHEAST OF THE 40N 70W BENCHMARK...WHICH IS SIMILAR TO THE HPCMEDIUM RANGE PRESSURES FROM SUNDAY AND MONDAY THOUGH ABOUT 200MILES SLOWER/SOUTHWEST.

12/24/2010 12z NAM simulated radar:

12/24/2010 12z NAM total QPF:

[imghttp://www.americanwx.com/bb/uploads/monthly_12_2010/post-67-0-24327900-1293201786.png[/img]

12/24/2010 12 GFS shifts way west and gives NYC 1.00-1.25" of QPF:

Taunton's AFD and HPC indicates model initialization runs with the 12z GFS:

HIGHLIGHTS

* POTENTIAL WINTER STORM SUNDAY THROUGH MONDAY.

SPECIAL NOTE AT 1140 AM...WE HAVE GOTTEN A GOOD LOOK AT THE 12Z NAM

AS WELL AS A QUICK LOOK AT THE 12Z GFS THROUGH TUESDAY /SO FAR/. WE

HAVE SEEN THE DRAMATIC TREND THAT THE GFS HAS TAKEN ON THIS RUN...AS

WELL AS THE W TREND ON THE NAM /THOUGH REMAINING WELL S OF THE

BENCHMARK/. WE WANTED TO NOTE THAT WE HAVE RECEIVED MESSAGES FROM

HPC ABOUT INITIALIZATION PROBLEMS ON BOTH THE NAM AND GFS RUNS THIS

MORNING. HAVING WORKED ON THIS DESK FOR THE LAST SEVERAL DAYS...ONE

THING THAT HAS SHOWN THROUGH IS THE LACK OF RUN-TO-RUN CONSISTENCY

BETWEEN INDIVIDUAL MODELS. WHILE WE ARE NOT RULING OUT A SHIFT TO

THE W...WE DO NOT WANT TO JUMP ON THE BANDWAGON EITHER. WANT TO

WAIT UNTIL WE GET A LOOK AT THE ECMWF RUN BEFORE MAKING ANY MAJOR

CHANGES.

12/24/2010 12z GFS ensembles comes way west show 1.00" of QPF for NYC metro:

12/24/2010 12z GGEM, UKMET and Euro are still out to sea mostly; while the 12z JMA and CRAS continues to be a big hit.

12/24/2010 12z FIMM shows an epic hit, while being out to sea for all the prior runs.

HPC then says that we should disregard the 12z GGEM and UKMET also:

THE NEW UKMET/CANADIAN ARE DIFFICULT TO EVALUATE FOR

INITIALIZATION SINCE WE RECEIVE A LIMITED AMOUNT OF DATA.

HOWEVER...THEIR SOLUTIONS LIE WITHIN THE EASTERN HALF OF THE

GUIDANCE ONCE THE INDIVIDUAL TROUGHS PHASE TO PRODUCE THE

DEEPENING LOW OFFSHORE...WHICH HAS CONSISTENTLY BEEN THE CASE.

THUS...INITIAL RECOMMENDATIONS ARE PRESERVED WITH CONTINUITY MOST

PREFERRED.

During that afternoon, ABC-7 on-air meteorologist says that the models have no clue if we will get a crippling snowstorm or just clouds.

[Ray8002]

• This Thread makes me depressed..
  

[earthlight]

• This Thread makes me depressed..
  

this, so much.

[Hailstorm]

this, so much.

I saw those responses coming. :DHonestly, when I relive this whole event to this day by reviewing the model images, discussions and posts, I almost get as giddy as I was during this time last year. I mean, Ian made a thread in the Mid-Atlantic forum to commemorate the 12/19/2009 storm last year and him and the rest of the posters there still update it with images today after two years. Although, they realize that they DC will likely not see a storm of that magnitude anytime soon. I don't blame them for creating a thread like that because it helps to ease off their boredom and depression nowadays.

[Ray8002]

At this exact time last year we were going crazy over the 00z GFS run.. This board was hopping that night! Man I miss it..

[MJO812]

The board was about to explode at this time last year.

[Hailstorm]

HPC afternoon discussion on 12/24/2010:

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD

355 PM EST FRI DEC 24 2010

VALID 00Z SAT DEC 25 2010 - 00Z TUE DEC 28 2010

DAYS 1-3...

..LWR MID-ATLC...

PRECIP WILL SPREAD INTO THE REGION LATE CHRISTMAS DAY AHEAD OF THE

APPROACHING DYNAMIC TROF... WHILE THE SFC FTR DEVELOPS IN THE ERN

GULF AND CROSSES FL. TRANSITION TO WET SNOW MIX SHOULD OCCUR

OVERNIGHT THEN CHANGE TO ALL SNOW AS CAA TAKES OVER ONCE THE LOW

ACCELERATES NWD OFF THE COAST. QUESTION REMAINS HOW MUCH PRECIP

WILL BE LEFT TO FALL ONCE THE THERMALS BECOME SUPPORTIVE OF SNOW.

CONSENSUS IS EMERGING DISCOUNTING THE 12Z GFS AND 18Z NAM... THAT

TAKES THE LOW FARTHER OFFSHORE AND BRINGS PERHAPS 1-2 INCHES TO

ERN/CNTRL NC AND EXTREME SE VA.

...NEW ENGLAND...

HPC CHOSE TO DEFER TO CONTINUITY HERE AFTER SEEING SPREAD OF 12Z

GUIDANCE. REGARDING SFC LOW OFF THE COAST... 12Z GFS/18Z NAM AND

SEVERAL GFS ENSEMBLE MEMBERS JUMPED WEST WHILE REMAINING HELD

SERVE OR TRENDED EAST. H5 EVOLUTION IS NEARLY AS

DISPARATELY-HANDLED AS AT THE SFC... WITH THE GFS AGAIN WRAPPING

IT TIGHTER AND FARTHER WEST. THERE WILL BE PLENTY OF DYNAMIC

ENERGY AS THE TROF GOES NEG TILT SUNDAY... AND THE DEEP LOW

OFFSHORE WILL PROMOTE A BURST OF HVY SNOWFALL TO PORTION OF NEW

ENG IN THE THE PREFERRED SCENARIO. STILL THINK CAPE COD AND NRN

COAST ME WILL SEE HEAVIEST AMTS WITH TIGHT ACCUM GRADIENT INLAND.

BLEND INCORPORATED 06Z GFS/00Z ECMWF REFLECTING PREFERENCE LOW

TRACK. STILL LOW CONFIDENCE HERE.

12/24/2010 18z GFS dumps 1.25-1.50" of QPF for NYC:

12/24/2010 18z GFS ensembles gives 1.00" for NYC:

Meanwhile, the HPC throws out the 12z and 18z GFS and NAM. Lee Goldberg forecasts 1-3" for NYC and says that the latest computer data is infected.

Steve. D's thoughts about the storm at this time:

"Over the past 12 hours, more data has become available to suggest the potential for a significant snow storm Sunday evening through Monday is growing. There is a great amount of uncertainty with this forecast, more so than I have ever seen with any other winter storm forecast. Model data is corrupted. Disturbances are stronger than forecasted. And to really make all of this interesting, not even the best ranked models can be trusted at this time. However, I have been tracking the latest observations and keep an eye on this storm, as promised; and I am currently elevating the threat for a region wide winter storm to moderate based on the latest upper level observations that are coming in. At this time, I am not changing the going forecast however if trends continue changes will have to be made for a more extensive winter storm impact for Philadelphia and New York City."

HPC 12/24/2010 probability map of accumulating snow of at least 4":

12/25/2010 0z NAM shows NYC getting 1.00" of QPF with a 963 mb SLP near Boston.

Steve. D's update after the NAM run:

"This NAM run is HUGE so far. It validates the idea of a significant snowfall along the coast and is an answer to the claim of bad data. As far as I can find from the HPC, there were no initialization problems. So this is the real deal here as far as a NAM solution. Nothing tainted. I don't go by the QPF thought, look at 850 MB to 500 MB, classic major snowfall signals for Philadelphia and New York City."

NWS Watch/Warning map at this time:

Impressive 850 mb wind charts in knots from the 0z NAM on 12/25/2010: