Extreme Cold, Snow & Sleet: SECS 1/24 - 1/26

[Brasiluvsnow]

51 minutes ago, MJO812 said:

Agree

Fv3 is all snow and a big thump 

How does the FV3 usually do with thermals ? 

[snowman19]

1 hour ago, MJO812 said:

We shall see. Nam can be amped but cant discount it since this is a new run.

I agree with you. Discount the NAM at your own risk at this range. Especially since the new RRFS is trending towards it. Over the years people have been burned really bad tossing the NAM in these types of setups

[allgame830]

4 minutes ago, eduggs said:

We go through this so often. And people cover their eyes and ears beforehand and pretend it didn't happen afterwards. When the NAM shows sleet it sleets. And the extent is usually north of where the 3rd party vendor graphics show it.

Nobody said it wasn’t going to sleet! You always seem to flip what people are saying. I still think 6-10 in the city is doable and areas north and west will see over a foot. I reside 30 miles north of the city and even with the NAM showing sleet up here around 4pm the damage has been done already with 8-12” by that time 

[SnoSki14]

2 minutes ago, snowman19 said:

I agree with you. Discount the NAM at your own risk at this range. Especially since the new RRFS is trending towards it. Over the years people have been burned really bad tossing the NAM in these types of setups

Yeah I'm leaning lower. I think ratios and thump still gets us several inches but it's clearly trending less and less. 

Under 6" honestly wouldn't surprise me now 

[jdj5211]

I don’t think the NAM is wrong, but I do have a hard time seeing sleet push all the way up damn near Poughkeepsie. The battleground for these storms is almost always that I-78 line and maybe a little further north.


.

[eduggs]

God that's an ugly sounding for NYC. I wonder if the warm layer being between 700mb and 850mb makes it less likely to show up on 3rd party graphics for other models... maybe other models don't generate and distribute temperature data in between the more common pressure heights.

[NEG NAO]

12 minutes ago, Astoriaweather said:

Besides the thermals, I guess I also worry that the storm ends up moving past us even faster than models suggest it will.  It seems that often ends up happening, unless its a prolonged overrunning or crawling coastal.   There have been plenty of times where we expect storms to last 12 hours but in reality they pass by in about 8 to 10. 

This  is the type of storm that will have some unexpected surprises - now casting time..........I also wouldn't be surprised if there is an unexpected large dry slot that develops because of a sloppy transfer of the storm to the coast

[SnoSki14]

3 minutes ago, eduggs said:

God that's an ugly sounding for NYC. I wonder if the warm layer being between 700mb and 850mb makes it less likely to show up on 3rd party graphics for other models... maybe other models don't generate and distribute temperature data in between the more common pressure heights.

Nothing we can do.

[eduggs]

7 minutes ago, Brasiluvsnow said:

How does the FV3 usually do with thermals ? 

Synoptically it tracks with the GFS. So usually too cold. Too bad though because it's a snowy solution... right into Mon. morning.

[wxman]

According to Gemini (aka "ask Jeeves"):

 

In 2026, the FV3 model (specifically in its High-Resolution Window and GFS implementations) is noted for a more conservative approach to "warm noses" (elevated layers of air above freezing) compared to older models like the NAM. 

 

Warm Nose Prediction Characteristics

• Layer Integrity: The FV3 tends to maintain colder column integrity better than the NAM. In winter weather setups, it often predicts a weaker or later-arriving warm nose, which can lead to forecasts for more persistent snow while other models might suggest an earlier transition to sleet or rain.

[WeatherGeek2025]

11 minutes ago, Brasiluvsnow said:

How does the FV3 usually do with thermals ? 

unreliable  model

[wxman]

Desperate times call for desperate measures!

[WeatherGeek2025]

reggie and gfs next

[wthrmn654]

1 hour ago, jm1220 said:

I take it as the worst possible outcome and the hi-res RGEM as the best because of the front end thump that still drops 10-12" despite changing most of us over. That said if sleet really makes it to I-84 those of us down here are screwed for anything major and we might struggle to make it to a warning criteria event. We're not there yet but by tonight if the NAM still totally sucks I'll take it more seriously. I didn't like the GFS cutting back at 6z either. NAM has been too aggressive with the warm layer in the past but it will probably be more right than other models close in. We should also monitor obs in the South/TN Valley for how far the warm layer is advancing vs what models have. 

My sister is in spring hill south of Nashville is snowing there already. Best real time updates possible. 

[SACRUS]

 

1/24 12z GFS 

 

[SACRUS]

 

Snow by 4AM

 

[SACRUS]

 

 

[samdman95]

Nothing we can do.

is there anything we can do about any weather?

[WeatherGeek2025]

1 minute ago, SACRUS said:

 

Snow by 4AM

 

i doubt that reaches the ground, it's very dry. I'd say 7am start time in the city proper

[SACRUS]

 

Heavy snow by 1:00 with sleet into far southern NJ

 

[SACRUS]

 

[WestBabylonWeather]

All we can do is hope several inches pile up before the changeover. It’s happening. Just have to hope for the best 

[Winterweatherlover]

Just now, SACRUS said:

GFS caved, sleet already into NYC at 4:00 pm tomorrow. 

[eduggs]

39 minutes ago, nycsnow said:

Icon is colder than nam and in nyc area it’s only .5- inch different from 06z so I’d say it held steady??

It also shows half the QPF as sleet (or rain - SNJ).

[Winterweatherlover]

GFS is just an absolutely attrocious model, 10 straight runs or so of all/mainly snow in NYC and now this. Why not get rid of the gfs instead of the NAM?

[MarcmmKU]

1 hour ago, donsutherland1 said:

Here's the HRRR's total snowfall map using the model's own assessment of the snow-liquid ratio:

I feel this is way too aggressive for I95

[eduggs]

FWIW I'm pretty sure the 10:1 counts sleet as snow on the Pivotal graphics for the RRFS. In this case the Kuchera algorithm (while not great) is better for visualizing snow accumulations.

[NEG NAO]

3 minutes ago, SACRUS said:

 

primary still in control and a sleet fest in progress across most of NJ except for the far southern counties - NOT GOOD !

[MJO812]

I think 6-10 is the best guess for NYC.  Nothing shows 12.

Gfs is trash

[WIN]

Amongst other things, the NWS has me at 7 to 13 inches, then ice. This forecast covers from central Delaware to NW NJ. Makes no sense, this should be broken into several different zones. They usually do that for these situations