Snow Potential Dec 26-27

[jm1220]

5 minutes ago, mob1 said:

HRRR with a significant NE shift unfortunately. Still very good for our area though, the main band just shift north from 12Z (still snowing here)

I don't see a big NE shift. Maybe 25 miles or so. And maybe came down a little on QPF. 

[weatherpruf]

1 minute ago, NEG NAO said:

this is obviously not as extreme - but I still consider myself here in extreme northern Middlesex County under a Winter Storm warning because Upton still has Union County under one .........

same spot here....hard to know which forecast to go with, mt holly or upton....i can literally walk to union co.

[forkyfork]

these north trends can sometimes continue right up until go time

[eduggs]

Not great micro trends for NJ. It would be nice to see the occasional southwest shift to counter the northeast nudges. But the changes have been happening early in the midwest, which makes it hard to reverse downstream. Maybe an inverted trof at the end of the event will overperform!  

What's bad for PA and NJ is good for NY and CT.

[wthrmn654]

If the forecast holds central park may see it's first significant snowfall sinceJanuary 28-29 2022 when 8.3 inches fell 

[NJwx85]

4 minutes ago, forkyfork said:

these north trends can sometimes continue right up until go time

I hope we get 3” of sleet. 

[mob1]

7 minutes ago, jm1220 said:

I don't see a big NE shift. Maybe 25 miles or so. And maybe came down a little on QPF. 

Gets a LOT better later in the run

[eduggs]

The pessimist in me says southwest of the NY-NJ border, this could turn into a quick (~2-4hrs) burst of steady snow followed by a period of light sleet and ending as flurries/snow showers.

[NEG NAO]

3 minutes ago, mob1 said:

Gets a LOT better later in the run

obviously Mt. Holly is discounting the HRRR as it shows heavier snowfall/sleet accumuation where they downgraded the warning

[eduggs]

Snow breaks out late morning on the HRRR for northern areas. Interesting that this has evolved into a Friday daytime event as opposed to a Fri night - Sat morning event.

[wthrmn654]

 

 

 

 

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FXUS61 KOKX 251934 AFDOKX Area Forecast Discussion National Weather Service New York NY 234 PM EST Thu Dec 25 2025 .SYNOPSIS... A cold front moves offshore through this evening. High pressure briefly returns tonight into Friday. A winter storm impacts the area late Friday into Saturday morning. A strong frontal system impacts the area late Sunday through Tuesday, with a weaker system moving through Wednesday into Thursday. && .NEAR TERM /THROUGH TONIGHT/... Key Messages: * A cold front moves offshore through this evening * Much colder air moves into the region with high pressure building down from southeast Canada. Mild and breezy conditions for the rest of the afternoon will turn much colder tonight. Arctic air will advect south out of southeast Canada with high pressure building southward. Dew points will lower significantly and should be in the single digits overnight with temperatures bottoming out in the teens inland and lower 20s closer to the coast. Breezy conditions also expected this evening with gusts 25-30 mph, gradually diminishing overnight. Wind chills by early Friday will be in the single digits to lower teens closer to the coast. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... What's Changed: Winter storm watches have been converted to warnings. A winter storm warning has been issued for eastern Suffolk and New Haven counties and a winter weather advisory has been issued for Middlesex county. Key Messages: * A winter storm will impact the area late Friday through Saturday morning. * The heaviest snow is expected to occur Friday evening (after 4 pm through about 1 am Saturday with lighter snowfall rates early Saturday. Travel will be impacted Friday evening into early Saturday morning. * Snowfall accumulations range from 4 to 8 inches in much of the warning area, 3 to 5 inches in the Advisory, and 1 to 3 just outside the Advisory in New London county. Global models and their associated ensemble systems continue to highlight a quick moving shortwave rounding a strong upper ridge centered over the central plains, approaching the local area from the northwest Friday afternoon. At the surface, a cold high pressure centered over Quebec heads to the east as a surface low traverses the OH Valley, through PA and generally south of the local forecast area by 12Z Saturday. This will allow for a cold and dry arctic airmass to remain in place at the start as the shortwave and sfc low pressure approach Friday afternoon. The modeling has shown slight adjustments over the last 24 hours, but the main message has remained consistent that strong frontogenesis and lift with couple with the left exit region of an upper jet streak to bring in widespread snow across the area late Friday through early Saturday morning. There has been some concern with the warm advection aloft, around H7, bringing in a a chance of sleet mixing in with the snow. This concern was indicated by the NAM, but the 12z has backed off somewhat and trended back south and west. Most of the rest of the guidance suite continues to be in good agreement with keeping any mixing out of the area. Warm advection does tend to come in a bit stronger than modeled, so felt it was warranted to introduce a slight chance of sleet for portions of NE NJ Friday night. This does not change the message and is currently not expected to impact snow accumulations. The majority of the significant snowfall accumulation will occur Friday evening and the first half of the night when the strongest thermal forcing (FGEN), middle level omega, and large scale synoptic lift coincide. These ingredients will lead to a band of heavy snow. Where this band sets up is still a bit uncertain, but guidance has largely been hinting at somewhere from the NYC metro through western Long Island and southwest Connecticut. The heavy snow band will gradually subside overnight as the lift weakens and saturation aloft begins to wane. Light snow accumulation is still expected through early Saturday morning, although the rates will likely be much lower. The event has come into the scope of the higher resolution models and they differ on the placement of the banding. However, they show the potential of this event well. The 12z HREF indicates a respectable probability (50-70%) of greater than 1 inch per hour rates beginning around 6-7pm from NYC metro on NW and then shifting south and east through 11pm. The 12z HREF also has probabilities of greater than 2 inch per hours of around 20-40 percent in the vicinity of the NYC metro, western Long Island, into the Lower Hudson Valley. This leads to growing confidence in heavy snowfall rates for several hours after sunset into the first part of the night as the heavy band moves across the region. While there is still uncertainty in the placement of the banding, there is enough confidence to upgrade the winter storm watch to a warning. We have also added New Haven and eastern Suffolk into the warning as guidance has trended towards heavier snow potential a bit further east. It should be noted that the eastern portions of the north and south fork will likely not reach warning criteria, but enough of the western half of the zone could easily see the 6 inch criteria met. Snowfall Accumulations: Forecast accumulations over the last 24 hours have not changed much with just minor adjustments and a slight shift eastward with the 6 inch amounts. Overall, 4 to 8 inches are forecast in the warning (average of 6 inches) with the exception of the forks of Long Island likely coming in lower. In the Advisory in Middlesex county, 3 to 5 inches forecast with 2 to 4 in New London. A reasonable worse case scenario in the warning area continues to be about 8-10 inches and around 6 outside the warning. The higher amounts are possible if banding were to put down a bit more snow or linger longer over specific areas than currently anticipated. If the forecast verifies, Central Park will receive its first snowfall of greater than 4 inches since January 2022. In the January 28-29, 2022 storm 8.3 inches was observed. Snowfall rates: Peak rates of 1-2 inch per hour are expected in heavier snow bands. There is a low chance rates could come briefly exceed 2 inches per hour in heaviest snow in banding, right now this appears isolated. Snow characteristic: There is likely going to be variability with snow ratios throughout the event, but the snow may begin a bit drier and become wetter as the event wears on. The banding potential also complicates this as within the band ratios will likely be high but in areas surrounding the band could be lower. Some light snow or flurries may continue Saturday morning before tapering off by midday. Any additional accumulation after 12z will be insignificant and likely just trace amounts. Clouds may linger into the afternoon, but we should begin seeing some clearing in the afternoon from north. Highs will struggle to rise above freezing, but should briefly get there closer to the coast. Cold temperatures remain in place Saturday night with lows in the teens inland to around 20 near the coast.

 

[Snowlover11]

Just now, eduggs said:

Snow breaks out late morning on the HRRR for northern areas. Interesting that this has evolved into a Friday daytime event as opposed to a Fri night - Sat morning event.

Always comes in earlier than modeled.

[NEG NAO]

1 minute ago, Snowlover11 said:

Always comes in earlier than modeled.

Starting at 6 AM tomorrow its now casting time and we should stop hugging the models and use real time data and the trends

[eduggs]

4 minutes ago, eduggs said:

Snow breaks out late morning on the HRRR for northern areas. Interesting that this has evolved into a Friday daytime event as opposed to a Fri night - Sat morning event.

Closer look it's actually virga. Snow looks to being in the afternoon on the model.

[mob1]

NAM moving north again. 

[mob1]

I'm going to vomit 

[eduggs]

No good on the 18z NAM. Not what we want to see at all.

[MJO812]

Just now, mob1 said:

I'm going to vomit 

Im not because its garbage and an outlier.

[MJO812]

Just now, eduggs said:

No good on the 18z NAM. Not what we want to see at all.

Dont fall for it. Nam does this all the time.  

[EastonSN+]

Lol

 

[Snowlover11]

Lmao, What a garbage model. Even shunks 40 miles north of the City

[psv88]

Anyone who freaks out over the NAM should be banned 

[eduggs]

The problem is all other guidance has been shifting north, focusing the snow northeast of the NY-NJ border. And we're squarely in the short range now. That makes it more difficult to dismiss.

[MJO812]

2 minutes ago, EastonSN+ said:

Lol

 

Northern areas arent going to see sleet

[MJO812]

Just now, eduggs said:

The problem is all other guidance has been shifting north, focusing the snow northeast of the NY-NJ border. And we're squarely in the short range now. That makes it more difficult to dismiss.

Nam is a horrible model. Throw it out unless the other models move to it.

[psv88]

Just now, eduggs said:

The problem is all other guidance has been shifting north, focusing the snow northeast of the NY-NJ border. And we're squarely in the short range now. That makes it more difficult to dismiss.

Relax and walk away for a while. 

[donsutherland1]

4 minutes ago, mob1 said:

I'm going to vomit 

It has virtually no support by any of the 12z GEFS and EPS ensembles. 

[forkyfork]

we still have another day for north shifts

[kat5hurricane]

1 minute ago, eduggs said:

The problem is all other guidance has been shifting north, focusing the snow northeast of the NY-NJ border. And we're squarely in the short range now. That makes it more difficult to dismiss.

There's not one other model that has jumped as far north as the nam, the jumps in the other models have been far more subtle. With that said, the north trend is a common occurrence so I would expect at least a nudge north by the other models and for the heaviest snow to go further north. Still, a 2-4, 3-5 inch storm for the immediate metro is nothing to scoff at.

[eduggs]

Warning snows to Saratoga springs with advisory snows to Lake George. That's rarely good for us. We don't blindly follow the NAM, but we shouldn't ignore a multi-guidance trend.

Good thing is the NAM is still cold enough for frozen precipitation for many areas even if the focus of heavy precipitation is north and there's more sleet now. It also would end as snow showers.