Pattern Change thread

[CT Rain]

Even the 12z GEFS has the torch signal early next week. Seeing a deep closed low/trough like that out west even with a -NAO is not a cold or even normal signal. The nice thing is the -NAO will cut the torch off earlier than it would have otherwise and prevent us from seeing record warmth... just solid above normal.

[OKpowdah]

lol 12z NAM dumps some decent snow over central-northern New England Wednesday

[Ginx snewx]

<br />Anyone else surprised that our first legit "cold threat" is being muted by a SE ridge that is flexing it's torch muscle?<br /><br />La Fail.<br />

Any one else surprised you would point this out? Expectations are the pattern change always is delayed. Again the timing looks great for Dec

[OKpowdah]

Excellent pattern for overrunning situations ... in about 20 days. In the 10 day range, still a little too warm.

[CT Rain]

Any one else surprised you would point this out? Expectations are the pattern change always is delayed. Again the timing looks great for Dec

Debbie Downer strikes again.

Seriously though I think most people expected a period of above normal weather Mon-Wed before Thanksgiving. No surprise. I think we may see a warmer stretch than first thought but in November what difference does it make? The models still look quite cool and wintry Thanksgiving and beyond and hopefully we can keep that signal past day 15.

[weatherwiz]

Excellent pattern for overrunning situations ... in about 20 days. In the 10 day range, still a little too warm.

Yup...we could be dealing with lots of those type of events. Some snow then heavy, heavy sleet for me.

[CT Rain]

lol 12z NAM dumps some decent snow over central-northern New England Wednesday

Yeah, nice snow storm

GFS and Euro still much further west. We'll see if we get some type of eastern trend develop soon? NAM leads the way????

[weatherwiz]

The NAO is more strongly correlated to us as we move through December and then into February than it is this time of year anyway.

[weatherwiz]

Was just trying to do something and came up with this...not sure if I went about it correctly but here it goes.

What I did was look back at past East-Based -NAO Decembers...I then looked at the 500mb configuration for the period of 11/26-12/7 and I looked at what today's 12z GFS had for height configurations in the 168-240 HR timeframe. The closest match I could find with November 26th, 1970 through December December 7th, 1970:

Not a perfect match as there doesn't appear to be a deep west-coast trough which is being advertised here.

Maybe what I'll do is also look back at East-Based -NAO Novembers and look at the same time periods listed above and see if anything else can come up.

[Tropopause_Fold]

12z ec ens look nice out toward day 10. heights are definitely coming down out in the GOA region but the NAO is just so strong it looks to be overwhelming the pattern in southern and eastern canada and starting to tap the cold by turkey day or thereabouts. nothing new really.

[nzucker]

Man 12z ECM is just ugly...SE ridge does not want to give up and cold is slipping back towards AK/NW Canada as heights lower in the Pacific with that block breaking down.

[CT Rain]

12z ec ens look nice out toward day 10. heights are definitely coming down out in the GOA region but the NAO is just so strong it looks to be overwhelming the pattern in southern and eastern canada and starting to tap the cold by turkey day or thereabouts. nothing new really.

It's been amazing how steadfast the models have been in the timing of this thing. They've all kept a Fri/Sat chill this week followed by a warmup (how much still a ?) then cold by turkey day. Nice job by the GFS and Euro!

[CT Rain]

Man 12z ECM is just ugly...SE ridge does not want to give up and cold is slipping back towards AK/NW Canada as heights lower in the Pacific with that block breaking down.

Is it that bad?

Mon-Wed torches next week but afterward it looks like it's ready to deliver a colder and stormy pattern for us.The op run just slows down the cold a bit with a sharper and slower to budge SE ridge.

[H2Otown_WX]

Man 12z ECM is just ugly...SE ridge does not want to give up and cold is slipping back towards AK/NW Canada as heights lower in the Pacific with that block breaking down.

Heavy, heavy panicking.

[nzucker]

Is it that bad?

Mon-Wed torches next week but afterward it looks like it's ready to deliver a colder and stormy pattern for us.The op run just slows down the cold a bit with a sharper and slower to budge SE ridge.

Yes, but the polar vortex is slipping back into Siberia and we're losing the much advertised cross-polar flow; all of the cold left in Canada is just going to rot behind the GoA/PAC NW low as the greatest negative anomalies have moved back to the Eurasian side. That low over Hudson Bay should deliver a decent airmass, but the pattern at that point is more +EPO and we've wasted the great blocking we had over the Pacific. It looks to me as if the PAC jet is very tightly packed at Day 10 on the 12z ECM with milder air moving into North America.

[N. OF PIKE]

Yeah, nice snow storm

GFS and Euro still much further west. We'll see if we get some type of eastern trend develop soon? NAM leads the way????

18z basically followed suit.....although snow line moved N about 100 miles .

[nzucker]

18z basically followed suit.....although snow line moved N about 100 miles .

Yes, I'm ready to believe we're going to have a mid November snowstorm when the 0C line starts 100 miles north of the border...but but don't worry, the storm will create its own cold air.

[CT Rain]

Yes, but the polar vortex is slipping back into Siberia and we're losing the much advertised cross-polar flow; all of the cold left in Canada is just going to rot behind the GoA/PAC NW low as the greatest negative anomalies have moved back to the Eurasian side. That low over Hudson Bay should deliver a decent airmass, but the pattern at that point is more +EPO and we've wasted the great blocking we had over the Pacific. It looks to me as if the PAC jet is very tightly packed at Day 10 on the 12z ECM with milder air moving into North America.

Yeah but I think that here in the NE with the -NAO we will be ok in that setup when the rest of conus warms up quickly.

Certainly no big arctic outbreak (that was off the table a couple days ago, i think) but enough for an active pattern with enough cold air for something to break right.

This is a great example how even the -EPO pattern which cools down most of CONUS isn't necessarily good for us as the SE ridge flexes and winds up screwing us with cold and snow in the plains and rockies.

[CT Rain]

Yes, I'm ready to believe we're going to have a mid November snowstorm when the 0C line starts 100 miles north of the border...but but don't worry, the storm will create its own cold air.

Well that did happen this past Monday lol

[Tropopause_Fold]

Yes, but the polar vortex is slipping back into Siberia and we're losing the much advertised cross-polar flow; all of the cold left in Canada is just going to rot behind the GoA/PAC NW low as the greatest negative anomalies have moved back to the Eurasian side. That low over Hudson Bay should deliver a decent airmass, but the pattern at that point is more +EPO and we've wasted the great blocking we had over the Pacific. It looks to me as if the PAC jet is very tightly packed at Day 10 on the 12z ECM with milder air moving into North America.

op runs on going to have boat loads of trouble right now.

[nzucker]

Yeah but I think that here in the NE with the -NAO we will be ok in that setup when the rest of conus warms up quickly.

Certainly no big arctic outbreak (that was off the table a couple days ago, i think) but enough for an active pattern with enough cold air for something to break right.

This is a great example how even the -EPO pattern which cools down most of CONUS isn't necessarily good for us as the SE ridge flexes and winds up screwing us with cold and snow in the plains and rockies.

The -EPO pattern is better for us when the block is oriented more over the Yukon/Eastern Alaska as we had in January 2009 rather than this glorified Aleutian ridge, which is typical in a La Niña and not necessarily that wonderful for us. The location of this block is allowing too much of a -PNA to form which then raise heights on the East Coast. Given where I live, I was rooting for the more arctic scenario since late November snows are a rarity in NYC metro and need to be accompanied by a good blast of cold air. From what I'm seeing, the models have been gradually modifying the cold pattern. First it was -15C 850s for Thanksgiving, then -10C 850s, now it's like -6C with the cold over Canada breaking down quickly thereafter. The 10-day period on the 12z ECM and GFS would average above normal in the big cities for sure.

op runs on going to have boat loads of trouble right now.

Yes, but even the ensembles are showing that we're not going to have the mega-arctic spell that was originally advertised. Looks like we're stuck with a -NAO battling a terrible Pacific signal, which won't cut it in late November except for NNE. The sign of a bad winter is the good pattern continually being delayed and modified.

[ChrisM]

it's always "10 days from now"

we'll still be saying that mid Dec.

[CT Rain]

The -EPO pattern is better for us when the block is oriented more over the Yukon/Eastern Alaska as we had in January 2009 rather than this glorified Aleutian ridge, which is typical in a La Niña and not necessarily that wonderful for us. The location of this block is allowing too much of a -PNA to form which then raise heights on the East Coast. Given where I live, I was rooting for the more arctic scenario since late November snows are a rarity in NYC metro and need to be accompanied by a good blast of cold air. From what I'm seeing, the models have been gradually modifying the cold pattern. First it was -15C 850s for Thanksgiving, then -10C 850s, now it's like -6C with the cold over Canada breaking down quickly thereafter. The 10-day period on the 12z ECM and GFS would average above normal in the big cities for sure.

Yes, but even the ensembles are showing that we're not going to have the mega-arctic spell that was originally advertised. Looks like we're stuck with a -NAO battling a terrible Pacific signal, which won't cut it in late November except for NNE. The sign of a bad winter is the good pattern continually being delayed and modified.

Good post, completely agreed. Obviously things don't look nearly as good as they did... though a cold and maybe stormy pattern after Thanksgiving seems likely.

[CT Rain]

it's always "10 days from now"

we'll still be saying that mid Dec.

The 8-10 day period on the models is a torch now lol

[ORH_wxman]

We should definitely have some chances here post-Thanksgiving. The -NAO should remain there for the time being and the leftover split PV migrates to SE Canada. One the reasons I put Nov 29th as my first 2"+ event. I think sometime in the 10 days post-Turkey Day we'll see our first event.

[ChrisM]

The 8-10 day period on the models is a torch now lol

i know...first itll be after thanksgiving, then early dec., then mid dec. and so on. too many mitigating factors, and you cant let what you want to happen get in the way of realizing that

[CT Rain]

We should definitely have some chances here post-Thanksgiving. The -NAO should remain there for the time being and the leftover split PV migrates to SE Canada. One the reasons I put Nov 29th as my first 2"+ event. I think sometime in the 10 days post-Turkey Day we'll see our first event.

Agreed. I don't think we're talking about bitter cold by any means but there should be enough along with a -NAO to keep things exciting.

[Tropopause_Fold]

The -EPO pattern is better for us when the block is oriented more over the Yukon/Eastern Alaska as we had in January 2009 rather than this glorified Aleutian ridge, which is typical in a La Niña and not necessarily that wonderful for us. The location of this block is allowing too much of a -PNA to form which then raise heights on the East Coast. Given where I live, I was rooting for the more arctic scenario since late November snows are a rarity in NYC metro and need to be accompanied by a good blast of cold air. From what I'm seeing, the models have been gradually modifying the cold pattern. First it was -15C 850s for Thanksgiving, then -10C 850s, now it's like -6C with the cold over Canada breaking down quickly thereafter. The 10-day period on the 12z ECM and GFS would average above normal in the big cities for sure.

Yes, but even the ensembles are showing that we're not going to have the mega-arctic spell that was originally advertised. Looks like we're stuck with a -NAO battling a terrible Pacific signal, which won't cut it in late November except for NNE. The sign of a bad winter is the good pattern continually being delayed and modified.

mega arctic spill?

[CT Rain]

mega arctic spill?

Sounds kinky

[ORH_wxman]

Agreed. I don't think we're talking about bitter cold by any means but there should be enough along with a -NAO to keep things exciting.

Yeah I don't think we'll be seeing any record lows challenged, lol....but it will be a below avg pattern and appears to be active as well and that's what you want to see. The lack of pure arctic cold this early will make it tougher for the coast line, but its always tough for them early on anyway.