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Sunday, December 19, 2010

Christmas storm (or the day after)

12-26 - NWS has all of the NYC forecast area in a Blizzard warning - expecting 15-20 inches. Started snowing around 11am, very light. As of 1pm (see pic), only an inch.

Latest GFS precip map


12/24 night - 18z runs of Nam and GFS concurred with the 12z gfs. MEts were throwing that run out as well due to bad data. Well I guess the data was bad for the 0z run of the NAm as well. The blue line goes all the way back to just west of the NY Thruway, with Danbury in the 6-10 inch range, or more. Crazy - East Mass is progged for 3" qpf. If that stayed all snow, even with a 8:1 ratio, its at least 24".

Nam has 972 on the BM, with the next spot a 964 low on the Cape. Astounding. Wondering when the NWS will pull the trigger on this instead of making excuses. Or are they trying to drive us nuts!

18z gfs ens have low inside bm, weighted west.

12/24 - afternoon

0z gfs had a nice run with us on the western edge with 6-10 inches
0z euro had placement of low just grazing the BM, but did not put out any liquid.
6 z GFS shifted east
12z GFS crushed us - see pic
12z Euro pushed further east of BM, by about 100 miles
NAM runs started off only major precip 200 miles east. 6z had the blue line on Cape Cod. 12z had the blue line back to Boston
JMA for the first time takes the storm over the BM
12z GFS ens were inside the BM
SREF ens are inside the BM with heavy spread bias west
CMC trended way west - from being 400 miles offshore to 200 miles with bulk of precip. CMC ensembles are pulling almost to the BM

So the consensus would be the adamant OTS models are shifting west, but not enough to affect NYC. The GfS may be messed up, as many are saying it did created a vort max too early.

12/23 - 0z run back on track with .5 precip NYC east to the Cape where its 1.75.

early afternoon

Models trending away

0z gfs had us in the 3-6 inch range
6z gfs pushed back into 6-10 inch range
12z gfs - ots - nada, but some flurries on Christmas nite
0z Euro knocks down to about a foot, perhaps 15 inches - no longer stalls south of li and just plows straight north, inside BM.
12z euro goes from OBX to CCOD, a tad further east. Looks like a decent track, but there is only .01 in precip
All nam runs look OTS
JMA pulled west, but not enough to hit us
DGEX pulled west, but not enought to hit us.
CMA - out to lunch. Doesn't even have a storm

12/21 - now its the day after the day after Christmas.

Low and behold, the GFS blinked. Its 12z and 18z precip runs are right off the coast, within 150 miles of the Euro. Precip images are above. GFS goes to a 976 low, but SE of the BM. Total snow of 2-4 inches

Euro 12z brings it to the mouth of the Delaware and to a 972 low (other sources had 968). Precip for DXR is 1.48, BDL is 1.52. Looking at the 850 temps of under -10C, there would be a lot of fluff, 15 inches per inch of liquid, for close to two feet in most of CT. Mixing should not be an issue either. Winds of 60-70 mph would hit ACK and perhaps the Cape. This situation looks so bad, it can't possibly happen.

Both models have a sharp right turn east south of long island.

While the models tracks are now within 150-200 miles, timing is still an issue. Euro has it snowing in NYC from 0z sunday to 12z tuesday. GFS moves in around 18z sunday and leaves by 12 z monday. Other example, GFS reaches the latitude of ACY at 3z monday. Euro is in the same spot 0z tuesday, almost a day behind.

Other models
JMA - out to sea
Nogaps - out to sea
DGEX - out to sea
UKMET - similar to the 18z GFS - puts a low too deep to register (I see at least a 97X) off OBX at 12z, so its track is like the gfs, but its stronger and slower.
CMC - bouncing around between the euro and the 18z GFs, 0z at BM but the 12z run is way out there giving us nothing

GFS Ensembles - bring the mean barely se of bm. The deepest spread is NW and there seem to be more members leaning west. Precip still at .25-.5, more than the operational.

Euro ensemble mean is east of the operational, with a heavy spread to the WNW.

12/21 - Midday (should be only post) - above are GFS precip maps, 12z Euro and 12z CMC

0z gfs has 1.25-1.5 in precip - beginning Sat morn with it maxing out at 984 just south of LI Sunday afternoon at 984mb. It stalls awhile after that and stops snowing at 156hr Mon morn

6z GFS has under .1 precip, ots to our south. It too has a 984 low a bit further south of LI, but the northern precip really doesn't make it to us.

12z GFS .01-.1 precip, ots to our south. It has flurries on Christmas. 1004 low off VA/NC going way out and improving.

0z Euro has .75-.1 precip with a 970 low going up the coast until Ocean county when it stalls and heads east. Precip looks too light based on that track. Snow not starting until 1pm Sunday/

12z Euro has 1.39 precip with it falling mostly Sun nite thru Monday. It parks a 968 Low right off the NJ coast and spins it out for 48 hrs. Truly amazing to see this - precip is still likely underdone, and with cold enough air, two feet is likely.

0z UKMet - out to sea
12z UKMEt 144 hr (Mon morn) has huge storm blowing up off OBX. May still go out, but not looking like it.

DGEX - out to sea
NOgaps - OTS
Canadian GGEM - similar to Euro. No precip estimates yet. The 0z run took it a little too far inland for my liking, but the 12z corrected east. Like the Euro, it stalls the system. I want to say I counted 54 hrs of snow out of it!

I would speculate that the GFS isn't seeing the northern branch energy coming in yet. Now the Euro is notorious for dragging its heels on systems coming out of the SW, which may explain the 1 day difference. But with the GEM and UKMET having the same look, it may be only slightly delayed.

If you discount the GFS, we have a major snowstorm starting Sunday and lasting through Monday. To be measured in feet.

12-20 evening

Posting above the 18z dgex which shows a 970 low off the coast of NJ . Its timing is slower, not starting until Sunday. The snow map that goes with it has over 15 inches in the tristate area.

The euro is a bit further east and faster now, but just as strong and still delivers snow. Its got 3-6 on the 12z run, compared to 6-12 earlier (and some areas had up to two feet). The ensemble spread is to the nw, but not by much.

GFS 18z run has over a foot in NE NJ and Westchester, with widespread 6-12 elsewhere. Light precip starts early Christmas day, but doesn't become heavy until night. The ensembles are out to sea though, with only 1-3 inches. The spread there is to the west. Odd to see the operational that far to the west, and not a good sign.

UKMEt 12 z never tilts the trough negative and closes off the upper low over PA, which normally is good, but it looks like the surface low escapes. But it only goes out to 144.

12-20 mid afternoon

Map of Euro solution and the precip map from GFS are above.

Looks like snow on the 26th, but just a matter of how much.

Euro solid on, a little too far west for us with the ensembles and their spread is to the north. Operational has a 980 low parked just south of LI by 0z 1/27. So its timing is more on the 26th than on Christmas

CMC - 0z brings a 993 Low off Delmarva at 144hr (8pm Christmas night). 12z run shoves it off to sea, whitening VA and NC.

DGEX puts 994 low off NJ by Christmas night, but heads it straight out, brushing CT.

UKMEt looks out to sea at 144hr

JMA - out to sea

GFS oz brings low out NC/VA border by 7am Christmas, only intensifies to a 992 just barely se of the bm by 7am the 26th, brushing the area with snow, but heavier in S NJ.

6z almost same track, a little slower and at 984 by the BM. Oddly, snow stretches back into all of NJ, but stays south of CT

12z low hits NC/VA coast 1pm on Christmas, heads out east a bit, then turns due north, over bm at 980 by 12z Sun. Results in fair amount of snow - 3-6 inches in NYC area, more in NE CT.



A day behind, but there is a chance for our real first snowfall to occur within 24 hrs of Christmas. GFS has been on this for all its runs, no switching between 6 & 18 v. 0 and 12. Euro is on board too. UKMET looks like its headed in this direction.

Posted are the GFS and EURO models. GFS precip is about 1-1.25 inches, so sizable snow, if indeed it falls as all snow. JMA suppresses the storm too, which is only interesting because its the only model who didn't crush the NE with snow today. Although, it did forecast a small amount.

Big fear of mine is that the storm phases too early, becomes to strong and brings in warmer air. Resulting in a snow-rain-snow combination.

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