Potential 3-5 day thaw coming

[ORH_wxman]

I thought I would start a thread on the longer term pattern development...beyond next week's storms threats.

This is probably not what winter enthusiasts want to see in the title of the thread, but its time to face the very real possibility of a decent thaw and period of milder weather before going back into a more wintry pattern. All ensemble guidance is beginning to hone in on a long wave pattern that supports a much milder regime over the CONUS...we'll try to get to New England specifics in a bit...but here are the GFS super ensemble analog guidance for day 8 (Feb 13)

Notice how there is a lot of troughing going on over Alaska and also in the PNA region. The ridging has been pushed well southwest of the optimal position for delivering cold into the CONUS. The leftover cold and lower height are still hanging on over the northeast US.

Now lets roll the analog dates forward 4 days:

The developing ridge in the SW US has now pushed well into the middle of the country and east of the Mississippi. Virtually zero arctic air to be found in the CONUS as the low heights over the PAC NW is mainly modified Pacific air.

Now another 4 days forward and we are in full torch mode on the composite.

But notice how the NAO and the EPO have just become to look more favorable on the last composite...the ensemble mean actually shows something similar which would spell the end of the milder period and begin dumping cold back into the CONUS...perhaps in the Feb 20-25 period. This could be the beginning of our winter finale over the late Feb to mid March period, though it could be more gradient.

The latest MJO forecast is in good agreement amongst the model ensemble guidance as well with a strong wave headed into phase 6 out of the circle of death. Phase 6 supports a PV well north as seen in this DJF composite of above avg amplitude phase 6 waves from RaleighWx's page:

However, if you remember from earlier in the season when we were first predicting cold in early December, you might recall that phase 6 was decent in December. Well its not so good later in the winter as this February-only composite for phase 6 shows:

You can it basically supports a torch in the eastern US.

As mentioned above, the pattern should come to end though fairly swiftly as the MJO wave is forecasted to go robustly into phase 7 and phase 8. Both of which support a much favorable Pacific pattern and a return to arctic cold to the CONUS. So while its possible we get pretty mild, it shouldn't be a long lived spell. I know Don Sutherland was pointing this out as well a few days ago in his thread on the main wx side. The NAO is also quite possibly going to come back into a favorable state as well, so we could see a pretty nice pattern set up in both oceans after we rid ourselves of this milder one.

The caveats:

-Ensembles show a pretty strong PV NE of Hudson Bay...more so than the analog composite would suggest. This can keep some sneaky cooler air into New England so we might only get a modified version of the milder look and still even sneak a few snow threats out of it with pseudo overrunning type storms.

-Ensembles have really struggled in the medium to long range over the arctic and especially with the NAO. NAO could build back and retrograde a ridge from Scandanavia sooner than what is modeled which wouldn't be terribly uncommon. That might push the PV SE more and cool off the northeast...particularly SE Canada and New England despite the ugly Pacific pattern.

- Low level cold might hang on tougher than the mid-levels in this set up.

[weathafella]

Very detailed analysis and well done. Thanks Will.

[Organizing Low]

sigh

thanks for the breakdown Will

[Damage In Tolland]

Low level cold needs to win out..plain and simple..Let's be on the look out for sneaky cold highs

[CoastalWx]

Good post.

You can see signs of the sneaky cold trying to come into the nrn tier on the op runs. However, the overall pattern is quite zonal as the Pac jet becomes active. My guess is that we don't rush into a cooler pattern, so the 20th to 25th is probably a good guess. Maybe even a few days later. However, any propensity to build heights in the NAO region will help ooze the polar airmss into New England.

This is becoming more of a classic Nina pattern with storms developing in TX and moving ne into the Oh Valley. We are gonna need the -NAO here to fight off any -PNA signal. If we have that, then it could be a nice wintry pattern for sne. If not, then it's more of a congrats Logan11 and sboswx.

[ORH_wxman]

Good post.

You can see signs of the sneaky cold trying to come into the nrn tier on the op runs. However, the overall pattern is quite zonal as the Pac jet becomes active. My guess is that we don't rush into a cooler pattern, so the 20th to 25th is probably a good guess. Maybe even a few days later. However, any propensity to build heights in the NAO region will help ooze the polar airmss into New England.

This is becoming more of a classic Nina pattern with storms developing in TX and moving ne into the Oh Valley. We are gonna need the -NAO here to fight off any -PNA signal. If we have that, then it could be a nice wintry pattern for sne. If not, then it's more of a congrats Logan11 and sboswx.

Or even congrats Hudson Bay. If it goes wrong, we could be torching right past the Canadian border, but hopefully the PV won't allow it that bad.

[Damage In Tolland]

I wonder if we'll melt all of our snowpack? That would truly be devastating

[CoastalWx]

I wonder if we'll melt all of our snowpack? That would truly be devastating

That would be almost impossible for you, unless we had cutter after cutter. This is legit snowpack.

[Damage In Tolland]

That would be almost impossible for you, unless we had cutter after cutter. This is legit snowpack.

I know...but if we get days and days of 50's with high dews and sun it's scary. Hopefully there'd be freezing at night

[Organizing Low]

I wonder if we'll melt all of our snowpack? That would truly be devastating

just hope for sneaky cold, i'm going to start praying tonight.

i'll contact my local politician on Monday to see what can be done.

[CoastalWx]

I'm glad Will made this thread, even though weenies hate it. It's the reality we face, with the possibility that the snowpack around here has peaked.

[weathafella]

I know...but if we get days and days of 50's with high dews and sun it's scary. Hopefully there'd be freezing at night

I just remember going up to Maine for business in late March 2009. Late March sun angle, plenty of mild days in the bank, and unreal snowpack. This won't go down so easy. Sure 2 weeks of straight 50s with warm nights might do it but even then I bet there'd be some. This is a snowlover's snowpack....it will take the spring thaw to do the deed. Just hope that spring thaw isn't this month.

[weathafella]

Ensembles beyond this upcoming week are warm......and the signal grows. Big time pattern break but hopefully under a week in duration.

[Organizing Low]

I'm glad Will made this thread, even though weenies hate it. It's the reality we face, with the possibility that the snowpack around here has peaked.

well at least you guys will still have a shot at alltime snowfall records....its certianly not the end of winter for many of you in SNE.

for myself, if i lose my pack, its the end of meaningful winter up here, as i am well below normal snowfall......but at least i have a chance to make a run at epic snowpack.

ill be ready for opening day if the PV retreats and the snowpack melts.

[weathafella]

I may try to go south during the thaw period.....might as well get some warmth before epicosity returns.

[OKpowdah]

Nice discussion Will!

I think Canada will stay nicely on the cold side through all of this, preparing to unload on us in the last few days of the month and into March as ridging develops over Alaska, and the NAO starts to look more favorable. For the time being, it looks like the strong La Nina is going to try to give us a taste of the winter that climatology said was on the way.

[CoastalWx]

Ensembles beyond this upcoming week are warm......and the signal grows. Big time pattern break but hopefully under a week in duration.

12Z for whatever reason cooled off big time in the 11-15 day. I do think we'll be playing cat and mouse games in the nrn tier with an arctic boundary. It's just too early to claim where it will end up. Worst possible case is that CAR is 6F while BOS is 45F. Could happen.

[Organizing Low]

I may try to go south during the thaw period.....might as well get some warmth before epicosity returns.

yeah i was thinking of going to California myself

this might be a good time to do it, if the signal continues to intensify and we get stronger ridging in the east.

[CoastalWx]

12Z for whatever reason cooled off big time in the 11-15 day. I do think we'll be playing cat and mouse games in the nrn tier with an arctic boundary. It's just too early to claim where it will end up. Worst possible case is that CAR is 6F while BOS is 45F. Could happen.

12z GFS ensembles actually have just that. Boundary just to the south of sne from day 12 on.

[ORH_wxman]

12Z for whatever reason cooled off big time in the 11-15 day. I do think we'll be playing cat and mouse games in the nrn tier with an arctic boundary. It's just too early to claim where it will end up. Worst possible case is that CAR is 6F while BOS is 45F. Could happen.

12z GEFS did one of the caveats I mentioned...tried to push the PV further SE so it gave the northeast a shot of decent cold while the rest of the country torched days 10-12.

[CoastalWx]

12z GEFS did one of the caveats I mentioned...tried to push the PV further SE so it gave the northeast a shot of decent cold while the rest of the country torched days 10-12.

Yeah I just took a look at the height difference at 500mb from 00z. Heights were higher across nw Canada and over ectrl Greenland. While not huge changes, I think it goes to show you how these height rises can force the PV to the south or se like you said, and slip the polar boundary south.

It's one ensemble run so obviously I wouldn't take it to the bank, but at least it goes to show you how a scenario to the cooler side can work out.

[Ginx snewx]

Hopefully as Will and Scooter said we stay on the cool side with some overrunning, caveat here is that colder trends seems the theme of this winter, could be a great thaw. I prefer my thaws dry and cool with lots of skiing. Guess I can go midweek Feb vacation cuz all the kiddies will be in school, bummer.

[HoarfrostHubb]

Hopefully as Will and Scooter said we stay on the cool side with some overrunning, caveat here is that colder trends seems the theme of this winter, could be a great thaw. I prefer my thaws dry and cool with lots of skiing. Guess I can go midweek Feb vacation cuz all the kiddies will be in school, bummer.

Only in towns like Tolland that have forgotten how to plow...

[chim chiminey]

the analogs look impressive but the actual models do not. Every run seems to delay the warmup and slice more and more of the torch further south and west.

The AO just peaked at +4SD an all we could muster from that is a cold rain.

Seems to me that teleconnectors should just be tossed this year. Our warmest days this winter, Jan 1/2, occurred in the heart of a strong -NAO period with a lakes cutter. The NAO may be the egg and not the chicken

[Tropopause_Fold]

nice write-up Will.

[nzucker]

Very well done, Will. Impressive analysis of the long range pattern.

The 12z ECM at Day 10 says that any thaw might be short lived...you can see how the monster -NAO is building heights across the entire arctic, trying to force the polar vortex back towards New England. Higher heights are developing over the West, and it looks as if we may see a +PNA/Rex Block.

[Semper911]

Thanks, Will, I really learn a lot from your posts.

What I don't understand is all the talk (mostly on other threads) of severe depression at the thought of all this beautiful snow melting. I mean, we were given a special treat this winter, and at some point it will all go away. I just feel grateful for the experience, and I will proudly salute it as it slips back into the water table.

Whata Winta!

[CoastalWx]

The long range is in pretty good agreement near d14-16 with both the 12z EC ensembles and now the 00z GFS ensembles. Both have very weak -nao ridging with a -pna pattern. However, both try to develop a -epo ridge, which seems to be a much more robust signal, then a -nao for now anyways. The PV remains ne of Hudson Bay, and imo, the mdt -epo ridging is what tries to build the cold in here, with the help of weak -nao ridging.

[nzucker]

The long range is in pretty good agreement near d14-16 with both the 12z EC ensembles and now the 00z GFS ensembles. Both have very weak -nao ridging with a -pna pattern. However, both try to develop a -epo ridge, which seems to be a much more robust signal, then a -nao for now anyways. The PV remains ne of Hudson Bay, and imo, the mdt -epo ridging is what tries to build the cold in here, with the help of weak -nao ridging.

Everything about that map looks mediocre, though, for a wintry pattern in SNE: the NAO block is much too east-based, the EPO manifests itself more of an Aleutian ridge which leads to lower heights in the west, and the SE ridge is getting out of control.

0z GFS was a torch in the long range:

This isn't too unusual for February in a strong Niña however...both 1988-89 and 1954-55 saw the trough shift into the west for most of February.

[Logan11]

I just had a 60 minute thaw from 12 to 1 AM..... Whew.. glad that is over and it's back down to 27.

Only in towns like Tolland that have forgotten how to plow...