Pattern Changing: Early December threats?

[wokeupthisam]

Secondly, no one in there right mind would be confident that a storm 10 days out would be a major snow event. Conversely, to be just as confident that a storm that far out won't be a major snow event is equally foolish. ... I for one feel we'll end up with a respectable showing here, we typically do. It's all a matter of perspective.

Completely agree. There are a million cliche's with the theme "wisdom of years"... Having that (years, lol) I think what is important is perspective. We in New England will have our share of snow. And now in this scientific age, no need to rely on the wisdom of years when a google search on climatology will tell you all you need to know. Model watching is FUN - when a 3-day blizzard shows up on the goofus, you don't run out to the grocery store and buy 15 gallons of milk. You watch to see if it verifies stronger (highly unlikely but wouldn't THAT be a hoot); weaker usually the case; or right on ( rare indeed!). More to the point of this thread, having confidence in ANY 10-day or longer outlook is a chasing of the wind. It's an exercise, a learning tool, not an absolute and certainly nothing to get emotionally invested in. In my 40+ years of weather enthusiasm, what most delights me is the variability and surprises. Not that a 20-inch forecast that verifies isn't FUN...

[ORH_wxman]

I'm not calling for a bad winter in your backyard, Pete, I'd predict around average snowfall and slightly above average temperatures. I doubt it'll be a blockbuster winter but it could still be decent for someone with 1400' elevation on the East Slope of the Berskhires.

The 12/2 system does look pretty bleak, though, honestly. You might see some flurries or light snow on the backside, but it's getting pretty close and none of the models have shifted away from the lakes cutter solution. 850s in NYC approach +10C; it's a very warm storm with tons of ridging ahead of it. Even the secondary gets going too late for SNE to see much of a snow threat. Will be a disaster for the ski areas.

And I actually agree with CT Blizz about the pattern later in the winter; it's not likely to be that great, as strong La Niña years tend to have an intense -PNA form by February. We're already seeing that the PNA is a problem, and the NAO breaking down later in the winter will make it even worse. It's just hard to argue against how strong the Pacific signal is right now:

As we go into December and beyond, the EPO is going to be much much more important than the PNA for Pacific signal. The PNA has little to zero correlation with New England snow OR temps. Its correlation is meaningful in November but not beyond. Its a different story as you head south through the M.A.

Basically, you can get equal amount of good setups and bad setups in a -PNA...but those setups depend on other features, not the PNA itself.

[CT Rain]

As we go into December and beyond, the EPO is going to be much much more important than the PNA for Pacific signal. The PNA has little to zero correlation with New England snow OR temps. Its correlation is meaningful in November but not beyond. Its a different story as you head south through the M.A.

Basically, you can get equal amount of good setups and bad setups in a -PNA...but those setups depend on other features, not the PNA itself.

Do you think that with a strong(ish) Nina the PNA becomes more important than during an ENSO neutral or El Nino event? With the propensity for a SE ridge to pop up in Nina winters I'd thinking the +PNA pattern will help temper that some.

[CT Rain]

here's the sfc T correlation to a -EPO in January.

Here's teh sfc T correlation to a +PNA

You can see the stronger correlation with EPO... but certainly not zero with the PNA. I imagine that in a Nina winter the +PNA may help even more than usual with tempering the SE Ridge.

[Organizing Low]

i just saw the 18z GFS, ahhh, if only

[wokeupthisam]

Do you think that with a strong(ish) Nina the PNA becomes more important than during an ENSO neutral or El Nino event? With the propensity for a SE ridge to pop up in Nina winters I'd thinking the +PNA pattern will help temper that some.

I think the effects of the Nina are more pronounced for NYC south, in NE there are other factors at play that make for more variable (less predictable) outcomes.

[ORH_wxman]

here's the sfc T correlation to a -EPO in January.

Here's teh sfc T correlation to a +PNA

You can see the stronger correlation with EPO... but certainly not zero with the PNA. I imagine that in a Nina winter the +PNA may help even more than usual with tempering the SE Ridge.

Well check Dec and Feb...virtually 0...when averaged DJF, its pretty much nil.

PNA always correlates with a SE ridge (or trough) no matter what enso state. Its part of its measuring domain.

[nzucker]

Well check Dec and Feb...virtually 0...when averaged DJF, its pretty much nil.

PNA always correlates with a SE ridge (or trough) no matter what enso state. Its part of its measuring domain.

I just think the -PNA will become particularly intense this year, combined with a relaxation of the NAO, which will promote more of a SE ridge pattern later in the winter as we saw during February 1955, for example. I think you guys will capitalize on some SW flow events but that the mean storm track will be shifting further and further west as the winter goes on.

[ORH_wxman]

I just think the -PNA will become particularly intense this year, combined with a relaxation of the NAO, which will promote more of a SE ridge pattern later in the winter as we saw during February 1955, for example. I think you guys will capitalize on some SW flow events but that the mean storm track will be shifting further and further west as the winter goes on.

Well we shall see when we add up the events and totals and analyze the pattern come April. Usually winter throws curve balls. I am always especially weary of almost complete consensus that Jan/Feb will be terrible.

-PNA doesn't bother me that much...it obviously bothers you. EPO is much more concerning for me.PNA just doesn't matter in the long run for snow or temps here through the cold season.In individual setups it can obivously be a maker or breaker, but its like 3rd or 4th on the list of any index I'm worried about.

[nzucker]

Well we shall see when we add up the events and totals and analyze the pattern come April. Usually winter throws curve balls. I am always especially weary of almost complete consensus that Jan/Feb will be terrible.

-PNA doesn't bother me that much...it obviously bothers you. EPO is much more concerning for me.PNA just doesn't matter in the long run for snow or temps here through the cold season.In individual setups it can obivously be a maker or breaker, but its like 3rd or 4th on the list of any index I'm worried about.

I also think the whole blocking structure of -NAO/-AO will weaken since we have a +QBO/low solar regime which isn't favorable for stratospheric warming events. As the polar vortex develops fully towards mid-winter, with the atmosphere feeling the effects of the La Niña reaching near-record levels, it will be hard to sustain the kind of blocking we have had for the past couple of years.

Also, the PNA is particularly important earlier in the winter. I think we've discussed amply how much influence it exerts on the November pattern versus the NAO in determining our temperature regime. It'll be crappy if we get screwed by the PNA early in the winter and then the NAO/AO later on.

[CoastalWx]

Boy still a ton of spread in the euro ensembles. The low develops nearby. moves east, but then retrogrades back towards sne. What a crazy solution pegged on the models.

[moneypitmike]

Boy still a ton of spread in the euro ensembles. The low develops nearby. moves east, but then retrogrades back towards sne. What a crazy solution pegged on the models.

Being more than a week out, wouldn't it be surprising if there weren't a ton of spread on the ensembles?

[CoastalWx]

Being more than a week out, wouldn't it be surprising if there weren't a ton of spread on the ensembles?

Well yeah that's a given, but when you have a low center that could be south of Block Island or 200 miles se of Sable Island, that is still a sh*tload of spread.

[CoastalWx]

I also think the whole blocking structure of -NAO/-AO will weaken since we have a +QBO/low solar regime which isn't favorable for stratospheric warming events. As the polar vortex develops fully towards mid-winter, with the atmosphere feeling the effects of the La Niña reaching near-record levels, it will be hard to sustain the kind of blocking we have had for the past couple of years.

Also, the PNA is particularly important earlier in the winter. I think we've discussed amply how much influence it exerts on the November pattern versus the NAO in determining our temperature regime. It'll be crappy if we get screwed by the PNA early in the winter and then the NAO/AO later on.

I'll have to look back at the 50's and 60's, but pretty sure we had a +QBO durig mdt/strong enso events and a -nao. Maybe it was coincidental that we didn't, but given the predictability of the QBO...it should be easy to find out.

I've also noted a correlation to strong -PDO events and cold in the northern tier. It's not as strong in the northeast, but the cold has made it into the nctrl US with ease during strong -PDO's. Some of these years featured -NAO's so not really a surprise there. There seems to be a relationship between -PDO and -NAO, especially back then.

[moneypitmike]

Well yeah that's a given, but when you have a low center that could be south of Block Island or 200 miles se of Sable Island, that is still a sh*tload of spread.

Thanks--I misunderstood your opening line there. Seems like everyone is sleeping in this morning!

27.8/21

[CoastalWx]

Thanks--I misunderstood your opening line there. Seems like everyone is sleeping in this morning!

27.8/21

Yeah models will have a horrific time figuring this out. It's also very possible this storm forms to our ne, and we are left with cold nw winds.

[moneypitmike]

Yeah models will have a horrific time figuring this out. It's also very possible this storm forms to our ne, and we are left with cold nw winds.

I think that's waht the 06z gfs is showing. Actually, outside of northern ME, that's essentially what is presenting to all of the northeast (of course, I might be reading that wrong).

[CoastalWx]

I think that's waht the 06z gfs is showing. Actually, outside of northern ME, that's essentially what is presenting to all of the northeast (of course, I might be reading that wrong).

Yep, you're right. I'm sure the 12z gfs will slam the low into CC..lol.

[moneypitmike]

Yep, you're right. I'm sure the 12z gfs will slam the low into CC..lol.

lol. Actually, that cold, dry nw flow would be the much more expected scenario, wouldn't it?

[CoastalWx]

lol. Actually, that cold, dry nw flow would be the much more expected scenario, wouldn't it?

It's certainly very plausible. It's one of those things, where I wouldn't expect anything until it continues to be modeled within 5 days out. At that point, we can get a little excited, but we can see huge changes..even within 5 days.

Remember the storm just after New Years? That thing was modeled to go into Block Island within 4-5 days out I think.

[Tropopause_Fold]

It's certainly very plausible. It's one of those things, where I wouldn't expect anything until it continues to be modeled within 5 days out. At that point, we can get a little excited, but we can see huge changes..even within 5 days.

Remember the storm just after New Years? That thing was modeled to go into Block Island within 4-5 days out I think.

yeah i think that was the one ray was touting as 78 redux

[moneypitmike]

It's certainly very plausible. It's one of those things, where I wouldn't expect anything until it continues to be modeled within 5 days out. At that point, we can get a little excited, but we can see huge changes..even within 5 days.

Remember the storm just after New Years? That thing was modeled to go into Block Island within 4-5 days out I think.

I don't remember--did that one wind up as one of the DC/BWI specials?

[CoastalWx]

I don't remember--did that one wind up as one of the DC/BWI specials?

No that was actually for sne. I had 10.5" in that. It was the one that produced like 48hrs of light snow. I don't think you guys had much, but it retrograded in from Nova Scotia and flipped a good chunk of Maine to rain.

[MaineJayhawk]

No that was actually for sne. I had 10.5" in that. It was the one that produced like 48hrs of light snow. I don't think you guys had much, but it retrograded in from Nova Scotia and flipped a good chunk of Maine to rain.

Yup, I stayed all white but further north was rain. It's what led to Cool Spruce's demise, probably. The most uninteresting 8.2" of snow I've ever had.

[Damage In Tolland]

One thing is for sure. We are all going to see some snow from that 12/5 storm

[Damage In Tolland]

No late night posts from Will on Euro ensembles..BAd news apparently

[CoastalWx]

No late night posts from Will on Euro ensembles..BAd news apparently

I already did. No real bad news and actually looked a little better than 12z, as the low was a little further south and developed closer to the sne coast, but the details will vary from run to run. This is for the 12/5 storm.

[Damage In Tolland]

I already did. No real bad news and actually looked a little better than 12z, as the low was a little further south and developed closer to the sne coast, but the details will vary from run to run. This is for the 12/5 storm.

Amazing how the models and ens. have all keyed in on that date seemingly for weeks

[CoastalWx]

Amazing how the models and ens. have all keyed in on that date seemingly for weeks

Yeah that date is pegged, but the question remains if we even see anything from it.

[Damage In Tolland]

Yeah that date is pegged, but the question remains if we even see anything from it.

There seems little doubt that we snow