Storm potential January 18th-19th

[WeatherGeek2025]

1 minute ago, anthonymm said:

Euro op, and every other physics based model except Canadian

euro ai and ai gfs is going to replace regular euro and regular gfs, is that true? it's not looking good for ai unless they end up being right which at this point even my feen self don't believe it!

[WeatherGeek2025]

nam whiffs for saturday 

 

edit:

we get a period after and it depicts a dusting

[WeatherGeek2025]

NAM WHIFFS FOR SUNDAY

i am done

[MJO812]

3 minutes ago, WeatherGeek2025 said:

NAM WHIFFS FOR SUNDAY

i am done

This is too close to throw in the towel.

[mob1]

3 minutes ago, WeatherGeek2025 said:

NAM WHIFFS FOR SUNDAY

i am done

It is what it is. It's been fairly obvious since this morning that this threat is DOA (but God forbid someone mentions it, they get jumped on like common criminals).

[MJO812]

6 minutes ago, mob1 said:

It is what it is. It's been fairly obvious since this morning that this threat is DOA (but God forbid someone mentions it, they get jumped on like common criminals).

Agree 

Saturday might be more interesting 

[donsutherland1]

2 hours ago, WeatherGeek2025 said:

euro ai and ai gfs is going to replace regular euro and regular gfs, is that true? it's not looking good for ai unless they end up being right which at this point even my feen self don't believe it!

The ECMWF has not said that the EC-AI will replace the operational model. It complements it. 

https://www.ecmwf.int/en/about/media-centre/news/2025/ecmwfs-ai-forecasts-become-operational

[Tar Heel Snow]

EDIT: Got a Rufus vort map from a friend on another forum and re-added the right NAM vort map

Our problem on the NAM to my untrained eye is that piece of energy in Manitoba. It really rushes to push our wave out to sea (obviously not having any blocking probably hurts too)

On our new buddy Rufus, our storm seems to be moving more quickly while the Manitoba wave lags behind, giving it a little more space to push west.

FWIW, what Rufus is doing synoptically makes more sense to me given the type of storm for the climo I'm used to down in North Carolina. But that doesn't mean it's handling the timing particularly better than the NAM. This would be an interesting test for a model that sounds like will eventually replace the NAM

Thi

This is our reward on the back end^

[eduggs]

The RRFS is very expansive with the precip. shield to the NW of the SLP. It's probably too expansive. I'm guessing a lot of that would end up as virga with that surface depiction combined with a weak 700mb low.

The RRFS, NAM12km and NAM3km have a frontogenic banding signature on Saturday.

[Tar Heel Snow]

1 minute ago, eduggs said:

The RRFS is very expansive with the precip. shield to the NW of the SLP. It's probably too expansive. I'm guessing a lot of that would end up as virga with that surface depiction combined with a weak 700mb low.

The RRFS, NAM12km and NAM3km have a frontogenic banding signature on Saturday.

Maybe so, I've seen this type of overrunning event really pump precip more than modeled due to WAA down south many times before. Might not be a thing here as much though. Probably putting too much hope into it at this point, but I was out of town for our two NY snows this year, and haven't seen a true winter storm in probably 4 years!

[eduggs]

1 minute ago, Tar Heel Snow said:

Maybe so, I've seen this type of overrunning event really pump precip more than modeled due to WAA down south many times before. Might not be a thing here as much though. Probably putting too much hope into it at this point, but I was out of town for our two NY snows this year, and haven't seen a true winter storm in probably 4 years!

I'm in a similar situation both this year and in recent years. And I agree about the anecdotal observation.

The RRFS is prone to wild swings (i.e. errors), especially beyond 48 hours. But it's still better to see it shift west than east. It's showing a significant snowstorm for NYC east and south on Sunday after an appetizer for some on Saturday.

[WeatherGeek2025]

reggie?

[Tar Heel Snow]

From Eric Webb (aka my current hopium dealer)

There are positive feedbacks between warm advection, precip, latent heat release, and wave tilt/amplitude that a lot of, if not most, models are going to miss in setups like these, which make them especially tricky to forecast. It’s easy for a lot of people and forecasters alike to get caught up in the models and underestimate the effect these processes and the magnitude of impact they can have on even a short range forecast. 

This positive feedback loop involves warm advection and upglide aloft generating more precip and latent heating, which force -PVa ahead of our upper trough, causing the wave to slow and tilt the over more negatively/less positively. The increased wave tilt is able to advect more warm/moist air aloft over the Arctic front, which triggers more precip, etc.

When your air mass is super marginal like this and the large-scale flow is diffluent downstream (ridging off Newfoundland), you’re even more vulnerable to this positive feedback running away in a hurry and amplifying the short-term changes in the models. This is just the kind of recipe that can lead to big forecast busts, especially on the north & west side of these systems where the warm advection is weaker but also closer to the snow growth zone aloft

[eduggs]

2 minutes ago, WeatherGeek2025 said:

reggie?

I love how it's snowier than 12z. Lovely model battle

[Tar Heel Snow]

This is a wildly difficult forecast. I mean it could literally be nothing outside of some Saturday mood flakes or we could see legitimate accumulations closer to the coast. I don’t envy the Mets who have to communicate this stuff to the public.

[eduggs]

1 minute ago, Tar Heel Snow said:

From Eric Webb (aka my current hopium dealer)

There are positive feedbacks between warm advection, precip, latent heat release, and wave tilt/amplitude that a lot of, if not most, models are going to miss in setups like these, which make them especially tricky to forecast. It’s easy for a lot of people and forecasters alike to get caught up in the models and underestimate the effect these processes and the magnitude of impact they can have on even a short range forecast. 

This positive feedback loop involves warm advection and upglide aloft generating more precip and latent heating, which force -PVa ahead of our upper trough, causing the wave to slow and tilt the over more negatively/less positively. The increased wave tilt is able to advect more warm/moist air aloft over the Arctic front, which triggers more precip, etc.

When your air mass is super marginal like this and the large-scale flow is diffluent downstream (ridging off Newfoundland), you’re even more vulnerable to this positive feedback running away in a hurry and amplifying the short-term changes in the models. This is just the kind of recipe that can lead to big forecast busts, especially on the north & west side of these systems where the warm advection is weaker but also closer to the snow growth zone aloft

Lovely write up. For a change I don't think it's all hype and BS. I seem to remember this feedback loop being enhanced when PVA tracked close to the Gulf states and picked up additional moisture inflow... which is what is forecast by most models to occur.

[WeatherGeek2025]

5 minutes ago, eduggs said:

I love how it's snowier than 12z. Lovely model battle

reggie is rain to long lasting snowstorm 4-5 inches

[Brian5671]

1 minute ago, WeatherGeek2025 said:

reggie is rain to long lasting snowstorm 4-5 inches

Round and round we go...but think a small event is in order here

[eduggs]

4 minutes ago, Tar Heel Snow said:

This is a wildly difficult forecast. I mean it could literally be nothing outside of some Saturday mood flakes or we could see legitimate accumulations closer to the coast. I don’t envy the Mets who have to communicate this stuff to the public.

I'm hoping for more than mood flakes on Sat as I expect that to be the snowier day for me. I think LI and southern NJ has a decent shot of accumulating snow on Sun. But I'm not closing the door on a significant west trend.

[mob1]

I'm hugging the RGEM so hard that it has difficulty breathing. 

[Franklin0529]

This threat is done. Icon is wayyy east. I want what the rgem is smoking 

[Brian5671]

3 minutes ago, Franklin0529 said:

This threat is done. Icon is wayyy east. I want what the rgem is smoking 

Better model than the NAM or GFS so I'll listen....

[eduggs]

Long range HRRR for Saturday.

[MJO812]

13 minutes ago, Brian5671 said:

Round and round we go...but think a small event is in order here

Yep most likely 1-3 inches 

[the_other_guy]

6 minutes ago, eduggs said:

Long range HRRR for Saturday.

If the HRRR has it (albeit long range) im tuned in

[the_other_guy]

5 minutes ago, MJO812 said:

Yep most likely 1-3 inches 

Then with temps in the 30s, the city wants and after dark storm

[MJO812]

Gfs AI still looks good

[MJO812]

Gfs is west. Gets some precip in here.

[donsutherland1]

My concern about Saturday is that temperatures in and around NYC will probably be around 34° during the snowfall. Even a GFS-esque burst of snow could result in a coating rather than several inches at such temperatures. That's why my current thinking is a coating to an inch. If temperatures could be a degree or two cooler, it would be easier for the snow to accumulate.

[Franklin0529]

Just now, MJO812 said:

Gfs is west. Gets some precip in here.

I give you props, you always go down with the sinking ship