January 2026 Medium/Long Range Discussion

[SnowenOutThere]

37 minutes ago, Terpeast said:

The map you just posted isn’t actually a “traditionally” neg PNA, but a transient gradient pattern where the index “computes” negative for a few days. More like a bootleg -PNA. However, I would feel better if we didn’t have troughing in the pac NW. We’d want ridging there to maintain the cold supply as the storm approaches here (even as a cut off low or energy undercutting the +pna ridge). I do like the atlantic side, we have a PV pressing down south towards us with confluence.

The biggest failure risk is that the western trough gets stronger, the TPV retreats north or NW, and the eastern ridge pumps, and the storm cuts. So far we haven’t been trending in that direction, though. 

The other end of the spectrum is where the PNA is so positive (with -EPO) that it suppresses the storm south. Right now that is the most unlikely scenario for that window.

In short, with -EPO and a strong TPV in SE canada, we’d root for a neutral PNA if not slightly positive. In this case, too much -PNA, cutter. Too much +PNA, suppression. But generally, we get our best snows snowstorms when the PNA is positive. 

btw this is why we like El Ninos. STJ undercuts the +PNA, which delivers the cold while we get gulf moisture from a STJ wave. Way simpler than trying to thread the needle during a Nina. 

Ah thank you. So basically when we're discussing the PNA for this time period its more so about the upper northwest instead of the California region. So basically we need better ridging to the north of the closed low to encourage high pressure and cold air transport while maintaining the TPV to anchor the high out east in place. Do we actually have any mechanisms for this stuff (particularly the TPV) to remain in pace to prevent the SER resurgence because otherwise it seems like a longshot with timing. 

[bncho]

Man is that GFS close to something significant

[Ralph Wiggum]

Minor shifts last 4 runs

[Ruin]

1 hour ago, winter_warlock said:

Never gonna happen lol

yeah we wont even get 5% of that lol

[SnowenOutThere]

0z GFS had a notable jump west with the precip and had it more widespread getting it all the way to the Eastern parts of our subforum. Had a good amount of upper air improvements as well but just couldn't quite consolidate quickly enough around the southern part of the vort due to an extremely annoying vort max which acts as a minor development blocker. 

I'm honestly not sure if we can get the trends all the way to the southern end where we ultimately need it to be (just seems unlikely to get that solution in this situation akin to this Thursday), but if we were able to it would be a major storm.  

[Terpeast]

1 minute ago, SnowenOutThere said:

Ah thank you. So basically when we're discussing the PNA for this time period its more so about the upper northwest instead of the California region. So basically we need better ridging to the north of the closed low to encourage high pressure and cold air transport while maintaining the TPV to anchor the high out east in place. Do we actually have any mechanisms for this stuff (particularly the TPV) to remain in pace to prevent the SER resurgence because otherwise it seems like a longshot with timing. 

Blocking would do it. Or a preceding strong storm that becomes a 50/50 low, ideally both.

One other thing I forgot to mention is the reason we don’t want troughing in the NW US is that it promotes a parade of GL lows, which has been a bane for us. That’s a characteristic of -PNA. We don’t get GL lows in a +PNA, instead we get cold highs. 

[Daniel Boone]

44 minutes ago, Terpeast said:

The map you just posted isn’t actually a “traditionally” neg PNA, but a transient gradient pattern where the index “computes” negative for a few days. More like a bootleg -PNA. However, I would feel better if we didn’t have troughing in the pac NW. We’d want ridging there to maintain the cold supply as the storm approaches here (even as a cut off low or energy undercutting the +pna ridge). I do like the atlantic side, we have a PV pressing down south towards us with confluence.

The biggest failure risk is that the western trough gets stronger, the TPV retreats north or NW, and the eastern ridge pumps, and the storm cuts. So far we haven’t been trending in that direction, though. 

The other end of the spectrum is where the PNA is so positive (with -EPO) that it suppresses the storm south. Right now that is the most unlikely scenario for that window.

In short, with -EPO and a strong TPV in SE canada, we’d root for a neutral PNA if not slightly positive. In this case, too much -PNA, cutter. Too much +PNA, suppression. But generally, we get our best snows snowstorms when the PNA is positive. 

btw this is why we like El Ninos. STJ undercuts the +PNA, which delivers the cold while we get gulf moisture from a STJ wave. Way simpler than trying to thread the needle during a Nina. 

Excellent Post Man ! 

[Terpeast]

2 minutes ago, SnowenOutThere said:

0z GFS had a notable jump west with the precip and had it more widespread getting it all the way to the Eastern parts of our subforum. Had a good amount of upper air improvements as well but just couldn't quite consolidate quickly enough around the southern part of the vort due to an extremely annoying vort max which acts as a minor development blocker. 

 

Sneaky trend for us. Let’s keep that going!

[SnowenOutThere]

2 minutes ago, Terpeast said:

Blocking would do it. Or a preceding strong storm that becomes a 50/50 low, ideally both.

One other thing I forgot to mention is the reason we don’t want troughing in the NW US is that it promotes a parade of GL lows, which has been a bane for us. That’s a characteristic of -PNA. We don’t get GL lows in a +PNA, instead we get cold highs. 

So I guess the GEFS shows signs of that but everything is too displaced north as of now. Will need to watch it though.

[Ralph Wiggum]

@CAPE gets CAPE'd with his 1/20 thing

 

[Chris78]

I'd gladly take what the cmc is showing for Saturday. 

A nice region wide 1 to 3 

[bncho]

GFS went poof for the @NorthArlington101 storm.

[NorthArlington101]

Yea, but UKIE likes the @CAPEstorm. 
 

[bncho]

It's not a cutter, it's not suppressed, it literally went poof. 100% gone. 

[SnowenOutThere]

3 minutes ago, bncho said:

It's not a cutter, it's not suppressed, it literally went poof. 100% gone. 

At least Ji doesn’t live in southern PA or else we’d have to hear about him “losing” 60 inches in one run 

[Chris78]

3 minutes ago, bncho said:

It's not a cutter, it's not suppressed, it literally went poof. 100% gone. 

The shortwave gets stuck in the SW

 

[Solution Man]

And just like that @Ralph Wiggum

[mitchnick]

8 minutes ago, Chris78 said:

The shortwave gets stuck in the SW

 

Gfs had to wait for us to lose the cold before bringing it out.

[bncho]

UKIE is super close to something for the cape storm. 2-4" verbatim I think.

[Solution Man]

3 minutes ago, bncho said:

UKIE is super close to something for the cape storm. 2-4" verbatim I think.

Let’s see it or it didn’t happen, never mind I see it, thanks

[bncho]

1 minute ago, Solution Man said:

Let’s see it or it didn’t happen 

It's a juiced up low, precip maps are broken so lots of that rain is snow falling at 33-34.

 

[Solution Man]

Just now, bncho said:

It's a juiced up low, precip maps are broken so lots of that rain is snow falling at 33-34.

 

Thanks, that’s getting ripe for the forum….drift baby

[bncho]

10 minutes ago, Solution Man said:

Thanks, that’s getting ripe for the forum….drift baby

1-3", not 2-4". 

 

[WEATHER53]

4 hours ago, SnowenOutThere said:

I think this is the single most ridiculous snow map I have seen for pretty much anywhere nearby. Would need to make a drive up to see 90 inches of snow. 

A bunch of us are booked for 7 springs Laurel Highlands 

[eduggs]

3 minutes ago, bncho said:

1-3", not 2-4". 

I agree the 1-3" characterization is better. But the event is not quite over for I-95 by 120hrs on the UK. But only a few hundredths of QPF after.

[bncho]

@CAPE gets buried. 1-3" for the cities, he gets 4-6"
 

[Kevin Reilly]

4 hours ago, SnowenOutThere said:

I think this is the single most ridiculous snow map I have seen for pretty much anywhere nearby. Would need to make a drive up to see 90 inches of snow. 

Will the sun angle be a problem with this storm?  LOL

[Kevin Reilly]

47 minutes ago, Chris78 said:

The shortwave gets stuck in the SW

 

Oh the classic hold back energy out west and I thought that was only a Euro thing.