Dec 21-22 MidAtl/NE Storm, Possibility: Medium Range (4-8 Days Out) Forecasts Options

[Mike W IN herkim...]

Euro for kuca

CODE

FRI 06Z 21-DEC   0.9    -1.1    1007      89      99    0.12     551     545    
FRI 12Z 21-DEC   1.4    -0.6     995      95      98    0.17     542     546    
FRI 18Z 21-DEC   2.2    -1.0     986      98      87    0.54     528     539    
SAT 00Z 22-DEC  -0.3    -6.2     988      88      91    0.10     521     531    
SAT 06Z 22-DEC  -0.7    -5.4     987      92      98    0.05     519     529    
SAT 12Z 22-DEC  -1.5    -7.3     990      93      97    0.11     519     526    
SAT 18Z 22-DEC  -2.3    -9.3     996      83      99    0.13     522     525    
SUN 00Z 23-DEC  -5.7   -13.1    1003      84      93    0.09     526     523

[windman]

Upton is going way too low with the wind forecast. GFS actually shows a moist adiabatic profile in the boundary layer at 12z Friday... With a LLJ of 70-80 kts that translates to High Wind Warning criteria winds in the usual favored areas, with upper-end Wind Advisory elsewhere, at least for the urban and coastal areas.

If I had to go with a range, I'd say the max winds will be 38-41 mph sustained with gusts 54-57 mph, occurring at either the LGA & JFK ASOS stations... Negatively titled storms tend to favor LGA with slightly higher winds than JFK, so I'd side with LGA for the max now.

Post-frontal wind also looks stronger based on the latest GFS run... With 850 mb winds over 70 mph Saturday evening and 925 mb winds over 60 mph. Even with this occurring after dark, this still would translate to winds near High Wind Warning criteria. 2/19/11 is a good analog to note... I recall we had a surge in the 850 mb jet in the evening into the upper 60s to low 70s mph, similar to what the GFS is showing, and we saw winds into the 40s sustained with gusts close to 60 mph for a couple of hours. If this jet max occurs a few hours earlier than progged, during the afternoon when mixing is at a maximum, you'll see some insane winds in the NYC metro.

Going with a range for max winds in the post frontal regime, I'd go with 39-44 mph sustained with gusts 51-56 mph, again with the max occurring at either LGA or JFK (slight higher favoring at JFK)... This is subject to more change, however, because if the low cuts off a bit further south, the max jet will be SW of the area and we'll see much lower winds than this.

[NYCSuburbs]

Upton is going way too low with the wind forecast. GFS actually shows a moist adiabatic profile in the boundary layer at 12z Friday... With a LLJ of 70-80 kts that translates to High Wind Warning criteria winds in the usual favored areas, with upper-end Wind Advisory elsewhere, at least for the urban and coastal areas.

If I had to go with a range, I'd say the max winds will be 38-41 mph sustained with gusts 54-57 mph, occurring at either the LGA & JFK ASOS stations... Negatively titled storms tend to favor LGA with slightly higher winds than JFK, so I'd side with LGA for the max now.

Post-frontal wind also looks stronger based on the latest GFS run... With 850 mb winds over 70 mph Saturday evening and 925 mb winds over 60 mph. Even with this occurring after dark, this still would translate to winds near High Wind Warning criteria. 2/19/11 is a good analog to note... I recall we had a surge in the 850 mb jet in the evening into the upper 60s to low 70s mph, similar to what the GFS is showing, and we saw winds into the 40s sustained with gusts close to 60 mph for a couple of hours. If this jet max occurs a few hours earlier than progged, during the afternoon when mixing is at a maximum, you'll see some insane winds in the NYC metro.

Going with a range for max winds in the post frontal regime, I'd go with 39-44 mph sustained with gusts 51-56 mph, again with the max occurring at either LGA or JFK (slight higher favoring at JFK)... This is subject to more change, however, because if the low cuts off a bit further south, the max jet will be SW of the area and we'll see much lower winds than this.

Agreed about the prefrontal wind setup; IMO a wind advisory mentioning the potential for a high wind watch is appropriate this far out. They're sometimes a bit slow with the high wind watches from what I've noticed in the past, at the very least I would expect a wind advisory with this. About the postfrontal winds I'm not so sure they end up that strong, but regardless of the exact strength it's going to be windy.

[windman]

Agreed about the prefrontal wind setup; IMO a wind advisory mentioning the potential for a high wind watch is appropriate this far out. They're sometimes a bit slow with the high wind watches from what I've noticed in the past, at the very least I would expect a wind advisory with this. About the postfrontal winds I'm not so sure they end up that strong, but regardless of the exact strength it's going to be windy.

The 12z GFS was the first run in a while to get us into the high winds for Saturday... Have to wait and see if this is a trend or just a fluke run. That's too far out for me to trust the NAM yet, and unfortunately the public ECMWF images are only every 24 hours, so it misses a lot of the key times.

[NYCSuburbs]

The 12z GFS was the first run in a while to get us into the high winds for Saturday... Have to wait and see if this is a trend or just a fluke run. That's too far out for me to trust the NAM yet, and unfortunately the public ECMWF images are only every 24 hours, so it misses a lot of the key times.

Some earlier model runs had us close but with the strongest winds to our south; I haven't followed a lot of the trends today but it seems there was somewhat of a north trend with the ULL and thus the further north winds. There's the Wunderground map for the ECM 6-hour intervals although it's been awful since TWC bought Wunderground, with some runs (such as both of today's runs) not running at all.

There's also widespread snow showers in the NE associated with this, with the further north ULL though the best chance of that outside the higher elevations would likely be north of NYC, towards the Hudson Valley.

[Mike W IN herkim...]

HPC day 3

[windman]

Some earlier model runs had us close but with the strongest winds to our south; I haven't followed a lot of the trends today but it seems there was somewhat of a north trend with the ULL and thus the further north winds. There's the Wunderground map for the ECM 6-hour intervals although it's been awful since TWC bought Wunderground, with some runs (such as both of today's runs) not running at all.

There's also widespread snow showers in the NE associated with this, with the further north ULL though the best chance of that outside the higher elevations would likely be north of NYC, towards the Hudson Valley.

The ECM on wunderground doesn't have the winds at different levels though, does it? I've looked at 850 and all it had was a few random vector arrows for the winds, not even barbs. It has 10m wind but I always like to look at the other levels.

[Mike W IN herkim...]

THE NATIONAL WEATHER SERVICE IN BUFFALO HAS ISSUED A WINTER STORM
WATCH...WHICH IS IN EFFECT FROM FRIDAY MORNING THROUGH SATURDAY
AFTERNOON.

* LOCATIONS...WESTERN SOUTHERN TIER...SOUTHERN ERIE AND WYOMING
COUNTIES.

* TIMING...FRIDAY MORNING THROUGH LATE SATURDAY AFTERNOON.

* HAZARDS...HEAVY SNOW ALONG WITH BLOWING AND DRIFTING SNOW.

* ACCUMULATIONS...1 TO 2 INCHES FRIDAY...4 TO 6 INCHES FRIDAY
NIGHT...3 TO 5 INCHES SATURDAY...LEADING TO STORM TOTALS OF 8 TO
13 INCHES. GREATEST AMOUNTS EXPECTED ACROSS HIGHER TERRAIN.

* WINDS...WEST 20 TO 30 MPH WITH GUSTS UP TO 35 MPH LATE FRIDAY
NIGHT AND SATURDAY.

* IMPACTS...TRAVEL CONDITIONS ARE EXPECTED TO DETERIORATE STARTING
ON FRIDAY. THE WORST CONDITIONS ARE EXPECTED FRIDAY NIGHT
THROUGH MIDDAY SATURDAY. EXPECT SNOW COVERED ROADS AND VERY
POOR VISIBILITY.

* FORECASTER CONFIDENCE...THERE REMAINS SOME UNCERTAINTY WITH THE
EXACT TRACK OF THIS LOW PRESSURE SYSTEM. A SMALL CHANGE IN THE
EXPECTED TRACK MAY ALTER EXPECTED SNOWFALL AMOUNTS.

http://forecast.weather.gov/showsigwx.php?...ter+Storm+Watch

[telejunkie]

HPC day 3

whoa...VT nicely outlined there, right up champlain and right down the CT River valley

[LoveNYCSnow]

NAM is very close to brief frozen precip even here tomorrow evening, not expecting much but if I see a few front end flakes I'll be happy.

NVM, 850s are better this run but surface is even worse and 925 temps are too warm, this looks like an all rain event here.

This post has been edited by LoveNYCSnow: Dec 19 2012, 09:40 PM

[HV Snowstorm]

All rain for us.........AGAIN, come on this is not how winter is supposed to be around here, like seriously, Global warming or climate change, whatever is happening go away and bring back the good ole' days.

[Mike W IN herkim...]

NAM is very close to brief frozen precip even here tomorrow evening, not expecting much but if I see a few front end flakes I'll be happy.

NVM, 850s are better this run but surface is even worse and 925 temps are too warm, this looks like an all rain event here.

The best chance for wide spread snow shower activity will be fri night/sat..

A W/NW CYCLONIC FLOW WILL DEVELOP
ACROSS THE REGION. FOR MOST OF THE HUDSON VALLEY AND SOUTHEAST PARTS
OF THE FORECAST AREA THIS MEANS SCT SNOW SHOWERS FRIDAY NIGHT...BUT
MORE WIDESPREAD SNOW SHOWERS IN THE CYCLONIC FLOW ARE LIKELY IN
UPSLOPE/LAKE EFFECT AREAS...ESPECIALLY LATE FRIDAY NIGHT. SOME
ADDITIONAL LIGHT ACCUMULATION IS POSSIBLE IN THE UPSLOPE AREAS...AND
HEAVIER AMOUNTS POSSIBLE IN LAKE EFFECT AREAS. LOWS FRIDAY NIGHT
WILL BE IN THE 20S.

LAKE ENHANCED MOISTURE
COULD LEAD TO MODERATE SNOW ACCUMULATIONS...ESPECIALLY ACROSS
PORTIONS OF HERKIMER AND HAMILTON COUNTIES. DUE TO THE SYNOPTIC
PATTERN IT APPEARS THIS WILL BE MORE A HYBRID UPSLOPE/LAKE ENHANCED
EVENT RATHER THAN PURE LAKE EFFECT. EVEN AREAS OUTSIDE OF THE
LOCATIONS PREVIOUSLY MENTIONED COULD EXPERIENCE SCATTERED SNOW
SHOWER ACTIVITY WITH SOME MINOR SNOW ACCUMULATION.

http://forecast.weather.gov/product.php?si...p;highlight=off

[LoveNYCSnow]

All rain for us.........AGAIN, come on this is not how winter is supposed to be around here, like seriously, Global warming or climate change, whatever is happening go away and bring back the good ole' days.

It goes in cycles, two winters ago was awesome for the Northern MA and I believe SNE as well. I also think starting next week the pattern should become more favorable for snow especially north of NYC.

[albanyweather]

0z GFS seems a little colder with the CAD. Actually holds the 850 line in the lower HV for 6 hrs. before it torches us here in Alb. 36 hr. clown map actually shows a couple inches here. I will believe it when its on the ground lol.

This post has been edited by albanyweather: Dec 19 2012, 10:52 PM

[LoveNYCSnow]

0z GFS seems a little colder with the CAD. Actually holds the 850 line in the lower HV for 6 hrs. before it torches us here in Alb.

So did the 0Z NAM but surface temps I think will be too warm for the immediate Hudson Valley Region. However west of the hudson valley should see a period of wet snow tomorrow night before changing to heavy rain.

[albanyweather]

So did the 0Z NAM but surface temps I think will be too warm for the immediate Hudson Valley Region. However west of the hudson valley should see a period of wet snow tomorrow night before changing to heavy rain.

Looks like we finally get some snow pack to the north and west from this puppy. That can only help in the long run

[albanyweather]

GEM is colder than the 12z run. Not much differance here but the Dacks do well.

[LoveNYCSnow]

GEM is colder than the 12z run. Not much differance here but the Dacks do well.

Pretty heavy snow tommorow night for the Dacks and even the Northern Catskills, Dacks may stay mostly snow. As you said at least there will finally be snow NW of the hudson valley and it seems like we will gradually begin to look more and more wintry.

[NorEaster07]

OBS thread opened for this storm.

http://forums.accuweather.com/index.php?showtopic=30309