SnowGoose69

The NAM idea of starting as sleet and then flipping to snow for a time is not very realistic...the RGEM going sleet/freezing rain most of the event makes more sense

Cancelled my V-Day dance, I was a very upset teen....setup was not bad, cold air was majorly lacking though...could have easily been all snow with a good air mass http://www.meteo.psu.edu/fxg1/NARR/1993/us0212.php

When you look at the wind directions on all models you can actually see the CAD signature develops as the surface low strengthens and approaches from the SRN Ohio Valley. Both GFS/NAM show winds 21-00Z try to go light 09-130...the GFS obviously turns them SE as it cannot resolve even the weak damming signature at this range...then past 02Z they back towards 040-060 again. I still question whether this is a snow event for more than an hour at the coast...its much safer to lean mainly sleet at this time

I'd say there is little chance if any this can evolve to be more than 1-3 hours of snow to start in NYC but it sure could evolve to be 80% frozen..rarely will a SWFE be 100% frozen in NYC...especially if its not predominantly snow...there has been only 1-2 SWFE events I remember which were predominantly ZR or P which stayed all frozen near the city

The CMC is an absolute disaster down here unless that is mostly PL...I still think this ends up north of the CMC but that may not help a ton if you want to avoid FZRA...if the CMC/GFS show the FZRA down that far it would in reality verify way further south and west than that as they do not see low-level cold air well at this range

There still needs to be more of a north shift than even the 12Z GFS in the end to avoid big icing problems for a large part of the area...its never good when at 96 hours even the low res in terms of seeing cold air GFS has FZRA down to EWR-HPN..that tells you in reality if that exact scenario unfolded it would be a good 30 miles south of that if not more

Yeah....it was more I think that the system was a sloppy non consolidated MSLP...the trof that dug into the OHV and MA was crazy deep, ultimately a surface reflection formed off the Delmarva on 12/5 which no model had forecast at all which led to the huge snows that day...there was still a weak low inland and I think thereafter the process of consolidation was all sorts of sloppy so we had two mesoscale areas of snow over C LI and E NJ on 12/6 and nothing in between.

Typically we only get one of those crap mid layer events when we have a real stale air mass in place or the system is an absolute bomb...in this case right now we do not really have either one at this range but that could change, especially the latter...the former I doubt as the air mass looks good

The CMC did not make a notable change...it probably was not as far north once it reached PA but its still mostly PL or RA near the coast..the CMC/Euro having that front running shortwave which washes out over the MA probably is having some impact on the end solution of the main system but at this range not sure how

I'm not as pessimistic as forky though he is correct about how far north the PV is...the main issue despite the high being in a decent spot is its almost too far west potentially...you'd really prefer that whole elongated high complex be about 500 miles more east and in place earlier...ultimately if the GFS track verified it would not matter but if something more amped happened you'd have a better shot at a long period of snow if the air mass was anchored in place for a day in advance and you had deep cold air..otherwise there would be a risk of a ton of sleet

The GFS is wrong given the pattern but the CMC is probably wrong too...the air mass is likely going to be good enough for a good 4-6 hours of all snow for the entire area to start...the SNE thread comparing it to 2/2/15 may be a good similar example.

The GEFS I think continues to be too ridgy in the SE past D10...that probably hurts us somewhat as far as storm chances as the EPS pattern is more cold dry. Its sort of unusual in shorter wavelength pattern to see a bootleg SER try to flex like that with an EPO ridge and the PV basically in E Canada so the EPS makes more sense to me given it'll be March

Often times in these marginal temp events, especially in Feb/Mar we will see airports report low...NYC usually won't though but we have had a bunch of storms over the years this time of year or later near 32-33 and JFK or LGA might report 4 while a person 2 miles away gets 6-7 in their yard

They only record .22 liquid though so I'm not sure...its an undermeasurement for sure but given the reliability of that ASOS to be close on LE I bet they got 2.3 or 2.4 at most...there were numerous little mesoscale area of subsidence and stonger bands

It has a tendency if temps are marginal to overdo things...in this event I feel we are just below the safe threshold based on T/Td wetbulb that most places should be cold enough but during the day we may lose some to sun angle

Euro keeps nudging more QPF NE past the NYC metro in that 06-12Z period again on the 18Z run

It sucks with mesoscale events...this is an event which 30 years ago the forecast would likely have no snow except for probably SE MA with the coastal...no models back then would have had the resolution to see the band of snow generated from DC up to NYC. The modern day GFS can sort of see that band but its misplacing it or thinking its going to be less significant. The NGM/LFM/AVN though probably would have had a totally dry forecast

Yeah the problem will be the light crap post 15-16z that some models show persisting, that probably won't accumulate but I doubt more than 10-15% of the total snow shown as of now falls after that time period anyway

The SPC HREF largely likes the corridor from TTN-WRI up across central and E LI where it indicates max potential of 5...it shows 1.5 around NYC on the mean with 2-2.5 over LI and almost all of C-SNJ

I would watch next Saturday...that boundary behind the cutter I do not feel will press as far down across the SE US or off the MA coast as currently modeled...the SER will probably flex more...something could possibly try to ride up the boundary behind the cutter

HRRR is usually too far NW at end of range, same as RUC/RAP had. The RGEM/Euro/3K is probably a safe bet idea. The GFS as usual due to resolution issues cannot resolve the frontogenesis/jet dynamics inducing that band and is probably washing it out due to the CAA that it thinks is drying out the lower and mid levels

The GFS won't budge on this one til the event is underway..this is typical outlier til the last minute on a coastal we usually see from it

Even the UKMET making moves now

The NAM/GFS did not show it in QPF but LI and cntrl-ern CT are back in this for sure as far as meaningful snow...I still think it organizes too late for NYC but there still probably will be more snow than the NAM/GFS show and more like the RGEM...the HRRR might be too generous

Not much...it'll just start to snow more QPF probably as it picks up on the jet feature and frontogenesis as Walt pointed out. I think the ceiling for the city with this is 3 wit the possibility ISP and east could see 5 but you'll still need continued improvement for that...1.5 and 3 are more likely