Isotherm Posted December 25, 2012 Share Posted December 25, 2012 This storm looks like a classic front end thump type scenario with the strongest vertical velocities occurring in the initial 3-6 hour period of the event. Given the cold air dammning via a 1028-30mb sfc high in Canada, a NELY ageostropic flow will be in place for the first several hours down to the coast. It's a bit too early to start talking specifics, but this could be interesting particularly for NNJ, Hudson Valley, and CT folks. Note the strong vv's arrive by 18z Wed-21z Wed when the 00z GFS has most of the region sub 0c 850's. 18z Wed: By 00z Wed we're already beginning to dry-slot on the GFS: Thereafter precip probably becomes lighter in intensity for the remainder of the storm. This has the look of a 6-8 hour burst of snow for the interior NW zones and potentially some accum down to the coast as well. Link to comment Share on other sites More sharing options...
MJO812 Posted December 25, 2012 Share Posted December 25, 2012 Heard that the rgem came in colder and further south. NYC also gets in on frozen precip. Link to comment Share on other sites More sharing options...
NYCSuburbs Posted December 25, 2012 Share Posted December 25, 2012 0z GFS is very borderline for the extreme NE NJ and Westchester areas... 2 frames (6 hours) are almost snow but just a little too warm at the surface. Just a little colder and front end flakes to heavy rain turn to heavy snow and major problems. Link to comment Share on other sites More sharing options...
isnice Posted December 25, 2012 Share Posted December 25, 2012 Wow that's a pretty significant thump on the 00z GFS. Surface params KSMQ: http://68.226.77.253/text/1DegGFS/GFS_KSMQ.txt Link to comment Share on other sites More sharing options...
Superstorm93 Posted December 25, 2012 Share Posted December 25, 2012 00z CMC has a very significant front-end thumping for the burbs. Could become very interesting if things trend slightly colder as well. Link to comment Share on other sites More sharing options...
Ericjcrash Posted December 25, 2012 Share Posted December 25, 2012 00z CMC has a very significant front-end thumping for the burbs. Could become very interesting if things trend slightly colder as well. Really trying to get the city involved. Link to comment Share on other sites More sharing options...
readingaccount1 Posted December 25, 2012 Share Posted December 25, 2012 Wow that's a pretty significant thump on the 00z GFS. Surface params KSMQ: http://68.226.77.253...FS/GFS_KSMQ.txt All rain at KTEB, KEWR and KTTN though. Talk about close. Link to comment Share on other sites More sharing options...
IntenseBlizzard2014 Posted December 25, 2012 Share Posted December 25, 2012 Incredibly close to Mostly Snow, eh? Link to comment Share on other sites More sharing options...
MJO812 Posted December 25, 2012 Share Posted December 25, 2012 Ukie is also colder and looks like the city gets in on some snow before it switches to rain. Link to comment Share on other sites More sharing options...
readingaccount1 Posted December 25, 2012 Share Posted December 25, 2012 All rain at KTEB, KEWR and KTTN though. Talk about close. I would like to see the soundings for Plainfield, NJ, or somewhere between KTEB and KSMQ. I would figure a few inches of snow would show up there. Link to comment Share on other sites More sharing options...
IntenseBlizzard2014 Posted December 25, 2012 Share Posted December 25, 2012 More and more SE trends. Probably some last minute shifts by late tomorrow morning. Link to comment Share on other sites More sharing options...
isnice Posted December 25, 2012 Share Posted December 25, 2012 I would like to see the soundings for Plainfield, NJ, or somewhere between KTEB and KSMQ. I would figure a few inches of snow would show up there. Even MMU is all rain too though. It makes me think that either KSMQ is a glitch, or the slight elevation in Somerset County gives it a slight advantage. Link to comment Share on other sites More sharing options...
readingaccount1 Posted December 25, 2012 Share Posted December 25, 2012 Even MMU is all rain too though. It makes me think that either KSMQ is a glitch, or the slight elevation in Somerset County gives it a slight advantage. It is surprising. KMMU at the same frame: 48 12/27 00Z 34 34 60 20 0.68 0.00 546 554 -1.5 -15.6 1008.0 100 RA KSMQ at the same frame 48 12/27 00Z 35 34 54 20 0.76 0.00 547 553 -0.5 -15.8 1006.4 100 SN Colder at the surface and lower thickness, yet KMMU rains and KSMQ snows? Probably not what will happpen. Link to comment Share on other sites More sharing options...
snywx Posted December 25, 2012 Share Posted December 25, 2012 0z GFS was a nice run for us NW folk.. Link to comment Share on other sites More sharing options...
sn0w Posted December 25, 2012 Share Posted December 25, 2012 Euro? Link to comment Share on other sites More sharing options...
snywx Posted December 25, 2012 Share Posted December 25, 2012 Euro? Still looks very good for much of Sussex, Orange counties.. Wunderground weenie snow maps show significant snowfall Link to comment Share on other sites More sharing options...
nzucker Posted December 25, 2012 Share Posted December 25, 2012 0z ECM has the 850 line passing through Southern Westchester at 54 hours, whereas the 0z GFS had the 0C isotherm all the way up to KPOU at 54 hours. Still much colder than the 0z GFS and gives a larger front-end dump. Maybe a tick warmer than 12z. Surface temps are in the mid 30s for NYC at 48 hours when it starts, but the City probably changes over at 51 hours due to warm BL and rising 850s. Their 850s are exactly 0C at 51 hours. Link to comment Share on other sites More sharing options...
MJO812 Posted December 25, 2012 Share Posted December 25, 2012 0z GFS snowmap shows 2-4 inches for NYC. http://raleighwx.americanwx.com/models/gfs/00zgfssnow048.gif Link to comment Share on other sites More sharing options...
readingaccount1 Posted December 25, 2012 Share Posted December 25, 2012 0z GFS snowmap shows 2-4 inches for NYC. http://raleighwx.ame...zgfssnow048.gif European Model? Link to comment Share on other sites More sharing options...
MJO812 Posted December 25, 2012 Share Posted December 25, 2012 European Model? Dont have the snowmap just yet. Link to comment Share on other sites More sharing options...
readingaccount1 Posted December 25, 2012 Share Posted December 25, 2012 It looks like it three or four inches in parts of NJ in six hours, and seven inches in northwest Sussex. European Model? Link to comment Share on other sites More sharing options...
nzucker Posted December 25, 2012 Share Posted December 25, 2012 Does anyone have good Euro analysis for NYC area? Looking for more details... Link to comment Share on other sites More sharing options...
readingaccount1 Posted December 25, 2012 Share Posted December 25, 2012 Still looks very good for much of Sussex, Orange counties.. Wunderground weenie snow maps show significant snowfall I guess there is your answer. Link to comment Share on other sites More sharing options...
nzucker Posted December 25, 2012 Share Posted December 25, 2012 I guess there is your answer. Looks like 1-2" followed by rain in NYC, 2-4" in southern Westchester and Rockland changing to rain, and further north in Orange/Putnam Counties a good chance at 4-8" with sleet/ice looking at the 0z Euro. Poconos/Catskills could be very icy following a moderate snowfall. This run had the 0C 850mb line a good 75 miles south of the 0z GFS, so definitely a nice hold on the part of the Euro. Link to comment Share on other sites More sharing options...
SnowGoose69 Posted December 25, 2012 Share Posted December 25, 2012 Looks like 1-2" followed by rain in NYC, 2-4" in southern Westchester and Rockland changing to rain, and further north in Orange/Putnam Counties a good chance at 4-8" with sleet/ice looking at the 0z Euro. Poconos/Catskills could be very icy following a moderate snowfall. This run had the 0C 850mb line a good 75 miles south of the 0z GFS, so definitely a nice hold on the part of the Euro. Now that we're close enough I looked at wind directions the NAM/GFS are forecasting. They show 060-090 for LGA/JFK/EWR as the event starts. Usually 060 is the direction where you begin to have problems for NYC metro, central and eastern LI usually you're easily done with that sort of direction. Its definitely possible to get front end shots of snow with those directions, it happened in March 93 and January 87 but the precip rates were very heavy both of those times. The biggest issue I see is the lack of sufficient wet bulbing room. The NAM would show dewpoints low enough to get evaporational cooling but the GFS has DPs already in the upper 30s by mid-afternoon Wednesday. Is it right? Maybe not, both models were showing dewpoints in the mid 30s earlier tonight 2 days back and they busted by 10 or more degrees. Link to comment Share on other sites More sharing options...
nzucker Posted December 25, 2012 Share Posted December 25, 2012 Now that we're close enough I looked at wind directions the NAM/GFS are forecasting. They show 060-090 for LGA/JFK/EWR as the event starts. Usually 060 is the direction where you begin to have problems for NYC metro, central and eastern LI usually you're easily done with that sort of direction. Its definitely possible to get front end shots of snow with those directions, it happened in March 93 and January 87 but the precip rates were very heavy both of those times. The biggest issue I see is the lack of sufficient wet bulbing room. The NAM would show dewpoints low enough to get evaporational cooling but the GFS has DPs already in the upper 30s by mid-afternoon Wednesday. Is it right? Maybe not, both models were showing dewpoints in the mid 30s earlier tonight 2 days back and they busted by 10 or more degrees. I totally agree about the wind direction being unfavorable...there's a sharp gradient that develops between the coast and interior in surface temperatures due to the easterly flow. For example, at 48 hours on the 0z Euro, it's pushing 40F at KNYC/Central Park while Central Westchester is around 33-34F. 850mb temperatures don't go above freezing for HPN until after 54 hours, so it's possible that Westchester continues to rip snow through hour 54 while the City is all rain by 48 hours out. One thing I've noticed is that precipitation can be very heavy ahead of a mix line in these strong SW flow events running into a high pressure, so there could be impressive rates involved allowing for more wetbulbing. But I'm sure there's going to be a powerful gradient where Central Park gets a coating to an inch, southern Westchester sees 2-4", and elevated areas of Putnam County see 4-8" with icing. Will be interesting to see how it plays out. Link to comment Share on other sites More sharing options...
CooL Posted December 25, 2012 Author Share Posted December 25, 2012 Not sure if we should be using the NAM but it continues with its warm and snowless solution despite no support Link to comment Share on other sites More sharing options...
SnowGoose69 Posted December 25, 2012 Share Posted December 25, 2012 Not sure if we should be using the NAM but it continues with its warm and snowless solution despite no support The NAM butchered this storm to death over the southern Plains and TN Valley and did not catch on til pretty much 24 hours out and was still playing catch up all day..I would not trust it at all downstream now considering everything else disagrees.....this was from the Tulsa AFD tonight.... LATEST TRENDS SUGGEST THAT THE STORM SYSTEM THAT WILL AFFECT THE AREA LATE TONIGHT AND TUESDAY WILL TRACK FURTHER SOUTH THAN PREVIOUSLY EXPECTED. IT APPEARS THAT THE UKMET WILL END UP BEING THE BIG MODEL WINNER ON THIS ONE...WITH THE ECMWF RUNNING A CLOSE SECOND. THE NAM WILL END UP WITH A FAILING GRADE ON THIS STORM. There could be some epic busts out that way, Tulsa based on some latest short range models may see nothing, OKC may see close to nothing too and some of those blizzard watches in parts of MO and other states may bust. Link to comment Share on other sites More sharing options...
CooL Posted December 25, 2012 Author Share Posted December 25, 2012 The NAM butchered this storm to death over the southern Plains and TN Valley and did not catch on til pretty much 24 hours out and was still playing catch up all day..I would not trust it at all downstream now considering everything else disagrees.....this was from the Tulsa AFD tonight.... LATEST TRENDS SUGGEST THAT THE STORM SYSTEM THAT WILL AFFECT THE AREA LATE TONIGHT AND TUESDAY WILL TRACK FURTHER SOUTH THAN PREVIOUSLY EXPECTED. IT APPEARS THAT THE UKMET WILL END UP BEING THE BIG MODEL WINNER ON THIS ONE...WITH THE ECMWF RUNNING A CLOSE SECOND. THE NAM WILL END UP WITH A FAILING GRADE ON THIS STORM. There could be some epic busts out that way, Tulsa based on some latest short range models may see nothing, OKC may see close to nothing too and some of those blizzard watches in parts of MO and other states may bust. Interesting. I guess the nam should not be used then until it falls in line with the other models who are all in good agreement. Link to comment Share on other sites More sharing options...
tmagan Posted December 25, 2012 Share Posted December 25, 2012 Some parts of Arkansas will see crippling snow from this system. Link to comment Share on other sites More sharing options...
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