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Winter 2014-2015 Pattern Discussion Thread III


BIG FROSTY

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Gotta get that LOW in the lakes and Northeast out of there and replace it with a H; then it's golden. 

 

Why do those lows appear there?  What is the mechanism that makes either or H or L develop in the northern tier?  Is it heigher heights at 5H?

There is a lot of energy in the northern stream. You'll get surface reflections of that energy up there the same way you do with southern stream energy. Low pressure spins up ahead of the energy and high pressure builds in behind. Often, those waves drop SE as clippers, though we haven't seen that type of pattern this winter very much. So far, they basically just move east through southern Canada. Once they go by, we cool down some.

Unfortunately, the timing is often such that a southern stream storm move through in tandem with or ahead of those systems, kind of like this one is showing. That northern stream energy needs to speed up and/or the southern stream system needs to slow down. That would allow high pressure to migrate into that area and create a cold air source with which to feed into any developing SE storm.

Of course, the Canadian has a big cutter, so it may all be a moot point anyway.

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The best way to see a high over the lakes is to have a ridge in southwest / south-central Canada, with a low or trough over the northeast states into SE Canada in the northern stream.  Sfc highs tend to be located downstream of ridges and upstream of troughs (location of sfc lows would be the opposite)  

 

Feb '04 storm below with this setup...high over the lakes, with gulf low in split flow.

 

 

 

 

There is a lot of energy in the northern stream. You'll get surface reflections of that energy up there the same way you do with southern stream energy. Low pressure spins up ahead of the energy and high pressure builds in behind. Often, those waves drop SE as clippers, though we haven't seen that type of pattern this winter very much. So far, they basically just move east through southern Canada. Once they go by, we cool down some.

Unfortunately, the timing is often such that a southern stream storm move through in tandem with or ahead of those systems, kind of like this one is showing. That northern stream energy needs to speed up and/or the southern stream system needs to slow down. That would allow high pressure to migrate into that area and create a cold air source with which to feed into any developing SE storm.

Of course, the Canadian has a big cutter, so it may all be a moot point anyway.

 

Thanks Grit, that helps.  You just had to bring up Feb 04 didn't you?! :snowing:

 

CR, fortunately there's lots of time for the timing to change.  I like this time frame the best so far this winter.  But it could end up cutting although there seems to be a bit of blocking on the Atlantic side this time...but maybe not enough to stop a cutter. 

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Do you expect the Atlantic to cooperate this winter? I know that historically, Feb is a better month for that in warm neutral years, but just curious if you believe we'll get some help there this year or if you feel like there is some other factor at play that will preclude any help on the Atlantic side.

 

Of course the north Pacific will continue to cooperate, that's not really been the problem the last two winters now. It's easily the easiest call to make with regards to the pattern as a whole.

 

The problem is , and continues to be on the Atlantic side of things.  I am encouraged by the signs we at least weaken the AO and NAO to neutral, but I have zero confidence in obtaining a sustained -NAO and -AO until it's too late to provide anything other than a miserable cold and rainy early spring.

 

I'm not really too worried about the NAO in either case and IMO it really doesn't matter if the NAO/AO are into positive territory, as long as the NE Pacific is blocked up, threats for Miller B/Overrunning will continue, and some great examples of this include the massive winter storms in February 1973 & December 1989, both I would quantify as overrunning, but neither featured any considerable amount of blocking over Greenland & the arctic...

Feb-6-8-1973-Southern-US-Overrunning.gif

Dec-19-21-1989-Southern-US-Overrunning.g

 

 

On the other hand, because we are within the multidecadal +AMO (@ least for now) we aren't likely to see the NAO continue its positive rout through February, as all the El Ninos/Warm Neutral events which featured a positive NAO/AO through December & January and didn't see the NAO flip sign in February were all in the cold multidecadal AMO phase... Even if the NAO & AO decide not to cooperate, I don't think we'll have too many problems... Reason I say that is using the El Nino monthly temperature composites, it's amazing to see how every single one of them, no matter the placement or intensity observe the core of the cold shift southeastward in February towards the SE US & eastern seaboard, and all of them are below normal, many well below normal at that. Of course, in a warm neutral-weak El Nino event like this w/ an extreme (record-breaking) +PDO offering even further support, the composite is still below normal even w/ a positive AO/NAO, lol.

US-Winter-Monthly-Temps-DJF-El-Nino-Plac

 

AO-DJF-US-temps-Warm-Neutral-Weak-El-Nin

Also, notice how small the sample size is for February in +AO composite, a testament to the seasonal modulation of the NAM by ENSO, i.e. a general lowering of the AO/NAO as the winter progresses. The proportion of +ENSO winters w/ a positive AO falls considerably from approximately 55% in December, to 35% in January, and eventually this number tanks down to 25% in February, Statistically speaking, this means the chance of seeing a -AO more than doubles in February vs December, that's very significant...

Top 20 El Ninos Northern Hemisphere 500mb December

Dec-N-hem-500mb-Top-20-El-Ninos.png

Top 20 El Ninos Northern Hemisphere 500mb January

January-N-hem-500mb-Top-20-El-Ninos.png

Top 20 El Ninos Northern Hemisphere 500mb February

February-N-Hem-500mb-Top-20-El-Ninos.png

 

AONAO-Monthly-Average-ENSOEl-Nino-1024x7

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The new CFSv2 is really cold after Jan 24....makes the new Feb forecast look like this....on the public site it will look pretty dang good for those following the CFSv2 for Feb.

 

Jan 29-Feb 8

 

Feb

FXERUtu.png

 

I definitely think the CFSv2 has the right idea, & is in compliance w/ a multitude of analogs & pattern regressions for other indices like the PDO for example, that argue for this kind of temperature distribution, core of the cold near the SE US & the eastern seaboard, warmer further north & west. Essentially, a +PDO/NINO February exemplifies a similar temperature *distribution* to its December counterpart, just a colder modification...

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Ummm...I haven't looked at the SFC yet...I don't CARE to be honest..LOL  The look on the new EURO At 500mb is a thing of freaking beauty!!!  Yes, the NAO is ok/meh the Pac is rebuilding, but give me that look with the PV stuck over the Northern great lakes...its lookout below ***IF*** enough arctic air/cold air can get into the pattern, which it should...That will also mean **IF** right, there will be NO cutters.

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Ummm...I haven't looked at the SFC yet...I don't CARE to be honest..LOL The look on the new EURO At 500mb is a thing of freaking beauty!!! Yes, the NAO is ok/meh the Pac is rebuilding, but give me that look with the PV stuck over the Northern great lakes...its lookout below ***IF*** enough arctic air/cold air can get into the pattern, which it should...That will also mean **IF** right, there will be NO cutters.

Can't look as I am out of the office, but is there a southern stream or does it hold as much potential that it's simply very cold and dry?

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Can't look as I am out of the office, but is there a southern stream or does it hold as much potential that it's simply very cold and dry?

Two shortwaves one quick, one hung back at 1/24...either one of these could give the east snow as it seems like 850s are fine. Pretty active, this doesn't seem to be a cold and dry look.

 

You can see it at 500mb, here's the EURO WMO-essential here

 

0Utfoav.png

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Can't look as I am out of the office, but is there a southern stream or does it hold as much potential that it's simply very cold and dry?

 

From days 7-10, it's basically a bowl trough across the lower 48 with weak waves traversing the southern periphery.  Looks good.  We need to see these east coast systems (Days 4-9) blow up in order to get the suppressed storm track and cold air on the backside.

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From days 7-10, it's basically a bowl trough across the lower 48 with weak waves traversing the southern periphery.  Looks good.  We need to see these east coast systems (Days 4-9) blow up in order to get the suppressed storm track and cold air on the backside.

 

Does day-4 start with Sunday's event?

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Two shortwaves one quick, one hung back at 1/24...either one of these could give the east snow as it seems like 850s are fine. Pretty active, this doesn't seem to be a cold and dry look.

 

You can see it at 500mb, here's the EURO WMO-essential here

 

 

From days 7-10, it's basically a bowl trough across the lower 48 with weak waves traversing the southern periphery.  Looks good.  We need to see these east coast systems (Days 4-9) blow up in order to get the suppressed storm track and cold air on the backside.

Thanks for the response. I have gotten back from my outside meetings and it's a great look.  Also, the events that throw this into motion are around day 4 to day 6 on both the GFS and Euro.  I have noticed in the last 48-72 hours we seem to be progressing toward a much better pattern quicker than initially anticipated and the trends have also been encouraging.  

I feel good about the last 7+ days of January FINALLY carrying a widespread winter weather threat with it and maybe more than one.

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Thanks Webber. Much appreciated.

 

Sure thing... I should mention aside from the Equatorial VP research (-VP 30-60E), the relationships I pointed out a week or so ago between MJO Phase 7 in January & a relatively higher frequency of winter storms here in NC held up nicely for the winter weather event we had last night & this morning across central-eastern NC.

NC-winter-storms-1979-present-and-MJO.pn

 

 

last.90d.noENSO.RMMPhase.png

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Better look on the Euro for a big dog...a bit of a swing and a miss with this run....but boy at 240 it looks like the fireworks are coming for late Jan. 

 

Yeah looking much better now with the thumb ridging over the N Atlantic.  Gotta get things to slow down and block up.  That, in addition to a +PNA ridge will really get things exciting pretty quick for us.

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Yeah looking much better now with the thumb ridging over the N Atlantic.  Gotta get things to slow down and block up.  That, in addition to a +PNA ridge will really get things exciting pretty quick for us.

We have just seen more improvement in the last 48-72 hours than we have all winter.  Will be nice to see if we can continue to close in on a MUCH better pattern.

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