Snow Potential Dec 26-27

[eduggs]

Playing catch-up with the afternoon's models and noticing that the 18z GFS is the best short range (24hr - 36hr) run for the ENTIRE NYC metro that we've seen in a while. An outcome like that would really spread the love. It's probably a bit optimistic, but still fun to see!

[Krs4Lfe]

1 minute ago, eduggs said:

Playing catch-up with the afternoon's models and noticing that the 18z GFS is the best short range (24hr - 36hr) run for the ENTIRE NYC metro that we've seen in a while. An outcome like that would really spread the love. It's probably a bit optimistic, but still fun to see!

Global models tend to Not do as well with warm mid level temperatures. We’ll see what the NAM says in a few hours, but these storms are known for producing sleet even far inland. Global models were quite warm with Friday’s event, almost all of them eaying around 2” for NYC but we were about 3-4 degrees too warm for that. That being said, it’s almost go time, so I don’t think global models should be looked at as much as the lesser models 

[sussexcountyobs]

Temp free falling here.

[snywx]

24/8 here

general 2” of snow cover remain 

[BxEngine]

Stop posting the kuchera nonsense

[Roger Smith]

13 minutes ago, Ravenz098 said:

Driving originally to Ohio tomorrow but Ice storm warnings got me staying in Williamsport Pa. When are the bad conditions starting in central Pa.?

Sent from my SM-S911U using Tapatalk
 

Looks like rapid spread into PA around noon EST, could be some freezing drizzle earlier than that. Maybe if you left very early (like 0400) you could make it to destination before the storm cranks up. This storm will tend to explode over a wide area rather than moving gradually, because it needs to saturate lower levels to get started. On the GFS hourly precip panels, it covers almost none of PA at noon and most of PA at 2 p.m.

[BoulderWX]

Just now, BxEngine said:

Stop posting the kuchera nonsense

Agreed 100% 

[lee59]

Down to 30 here. 

 

 

 

[WeatherGeek2025]

Nam rolling...

[eduggs]

Nice run from the 0z HRRR for NYC north and east. It even keeps light snow going into Saturday morning. Sleet mixes in briefly to the NY border.

But... major snow to ALB, plowable to ORH, and accumulating to BOS is a bit of a red flag for us. The 700mb low is getting pretty far northeast before getting shunted south... For now we're all still very much in the game but still feeling nervous.

[Snowlover11]

Down to 27F

[Stormlover74]

29 minutes ago, Rjay said:

1/23/16 NAM school every model

Well yeah that one too

[anthonymm]

4 minutes ago, eduggs said:

Nice run from the 0z HRRR for NYC north and east. It even keeps light snow going into Saturday morning. Sleet mixes in briefly to the NY border.

But... major snow to ALB, plowable to ORH, and accumulating to BOS is a bit of a red flag for us. The 700mb low is getting pretty far northeast before getting shunted south... For now we're all still very much in the game but still feeling nervous.

not necessarily. dec 2020 albany was the jackpot but the city still received a healthy 10".

[WeatherGeek2025]

[WeatherGeek2025]

Nam way south 

[eduggs]

On the HRRR, at 0z Sat (tomorrow), Orange County is at 2-4" while NYC metro is < 1". It's not the best angle of approach locally and there's still some concern there that the best banding could slide north and east into CT.

On the plus side, the HRRR still manages respectable QPF locally and the low level convergence (inv trof) overnight Sat occasionally manifests as undermodeled localized banding.

[Nibor]

1 minute ago, WeatherGeek2025 said:

Nam way south 

Not the warm nose. Sleetfest.

[WeatherGeek2025]

Just now, Nibor said:

Not the warm nose. Sleetfest.

yes but we already know Nam sucks so correcting like we expected is a great sign we're going to get clobbered

[cleetussnow]

25 minutes ago, Krs4Lfe said:

Global models tend to Not do as well with warm mid level temperatures. We’ll see what the NAM says in a few hours, but these storms are known for producing sleet even far inland. Global models were quite warm with Friday’s event, almost all of them eaying around 2” for NYC but we were about 3-4 degrees too warm for that. That being said, it’s almost go time, so I don’t think global models should be looked at as much as the lesser models 

Put the pipe down with the Nam. Its taking a dirt nap for a reason.  It fucking sucks.  

[eduggs]

4 minutes ago, anthonymm said:

not necessarily. dec 2020 albany was the jackpot but the city still received a healthy 10".

That was a huge snowstorm and the NYC area was clearly on the fringe.

[Krs4Lfe]

Just now, eduggs said:

On the HRRR, at 0z Sat (tomorrow), Orange County is at 2-4" while NYC metro is < 1". It's not the best angle of approach locally and there's still some concern there that the best banding could slide north and east into CT.

On the plus side, the HRRR still manages respectable QPF locally and the low level convergence (inv trof) overnight Sat occasionally manifests as undermodeled localized banding.

And in storms like this, the heaviest band creates a subsidence zone to the north  and south of the band where there is usually poorer snow growth and weak snow rates. I think the northern extent of this storm is likely further north than most models are saying. I’m not saying that necessarily translates to a bust for the NYC metro, but I can see lots of sleet south of that heaviest band (wherever that band sets up)

[WeatherGeek2025]

Just now, eduggs said:

That was a huge snowstorm and the NYC area was clearly on the fringe.

completely different setup! I don't think Albany gets more snow than NYC out of this but of course the under measuring thing with Central Park could happen

[donsutherland1]

30 minutes ago, Krs4Lfe said:

Global models tend to Not do as well with warm mid level temperatures. We’ll see what the NAM says in a few hours, but these storms are known for producing sleet even far inland. Global models were quite warm with Friday’s event, almost all of them eaying around 2” for NYC but we were about 3-4 degrees too warm for that. That being said, it’s almost go time, so I don’t think global models should be looked at as much as the lesser models 

This was the NAM just over 12 hours before the onset of Tuesday's precipitation for NYC:

Outcome: Trace not 2.4". 

 

[sussexcountyobs]

2 minutes ago, Krs4Lfe said:

And in storms like this, the heaviest band creates a subsidence zone to the north  and south of the band where there is usually poorer snow growth and weak snow rates. I think the northern extent of this storm is likely further north than most models are saying. I’m not saying that necessarily translates to a bust for the NYC metro, but I can see lots of sleet south of that heaviest band (wherever that band sets up)

If as you say there's alot of subsidence to the north and south of the heaviest snow band. Why would you say you could see ALOT of sleet south of that band? That would not be subsidence??

[the_other_guy]

Accuweather just jumped me from 3-6 to 6-10. I think everyone needs to calm down.

 

[mob1]

NAM is far from ideal but at least it improved.

[jm1220]

6 minutes ago, cleetussnow said:

Put the pipe down with the Nam. Its taking a dirt nap for a reason.  It fucking sucks.  

When it comes to how far the mid level warmth gets I don't ignore it because as others point out it's closer to accurate most of the time. And soundings do get dicey for the city from 0-3z especially, that 750mb warm nose will mean business. Even my backyard gets very close to changing to sleet. If we see good snow surging into eastern new England, NYC very likely changes to sleet. The block has to shove this south in time. But no I don't think it's gospel and I've seen situations where it overdid the mid level warmth. However it's probably closer to right than the colder models and I don't buy for a second that a storm like this will drop good snow from TTN-PHL with a 700mb low in upstate NY. 

[eduggs]

3 minutes ago, donsutherland1 said:

This was the NAM just over 12 hours before the onset of Tuesday's precipitation for NYC:

Outcome: Trace not 2.4". 

 

Don, I think you know that's not NAM output. That looks like Pivotal 10:1 "clown" map. NAM produces liquid precipitation output and a vertical temperature profile. I believe it also generates a ptype. I recall it did pretty well on all three. Just because you get 0.2" liquid with mostly snowflakes doesn't mean they will accumulate. That's not the NAM's fault. That's user error.

[TJW014]

I think all this flip flopping we're seeing with the models is them trying to simulate where the heaviest banding sets up, rather than how far the warm nose edges in.

Given all the trends today so far, there's little change in temps aloft. For nearly all of us that we stay below freezing up to 700mb until the wee hours of the storm when precip is winding down. 

All these jumps north/south are figuring out the heaviest bands. Lift vs subsidence. Someone's gonna be sitting under a weenie band, and someone 10 miles north or south is going to be screwed. 

[Snowlover11]

NAM did come south, still sucks from extreme northern nj, westchester, and down. This thing was extremely north before though.