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December-winter is finally here!


weathafella

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So it seems we have to cycle though some crap 11-15 but there appears to be some light at the end of the tunnel? 12/15-20 maybe?

 

 

My guess is at least that long until a real regime change. The +NAO is really hurting the pattern...it is usually more pronounced in an El Nino than La Nina when we can get away with a +NAO.

 

We'll see how much things change though over the next week in the mid-month look...I don't have a lot of confidence in the 11-15...really not for the past 2-3 weeks. They've been poor. But the warmup over the CONUS looks real...it's the duration that is the question...the longer the duration, the more likely it is that we will be affected locally. Initially, we are a bit shielded from the warmer weather, but mid-month and beyond, we may not be if we don't see a flip.

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the sensible weather difference by dawn and heading thru the day tomorrow is going to be equally epic... 

 

May not get out of the 30s where overrunning cloudiness immediately ensues post cfropa overnight...  One of those synoptic evolutions where there might be more cold push in the 925mb level than the 850 sigma.

 

Discussed this a bit yesterday.  

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My guess is at least that long until a real regime change. The +NAO is really hurting the pattern...it is usually more pronounced in an El Nino than La Nina when we can get away with a +NAO.

 

We'll see how much things change though over the next week in the mid-month look...I don't have a lot of confidence in the 11-15...really not for the past 2-3 weeks. They've been poor. But the warmup over the CONUS looks real...it's the duration that is the question...the longer the duration, the more likely it is that we will be affected locally. Initially, we are a bit shielded from the warmer weather, but mid-month and beyond, we may not be if we don't see a flip.

 

My guess is at least that long until a real regime change. The +NAO is really hurting the pattern...it is usually more pronounced in an El Nino than La Nina when we can get away with a +NAO.

 

We'll see how much things change though over the next week in the mid-month look...I don't have a lot of confidence in the 11-15...really not for the past 2-3 weeks. They've been poor. But the warmup over the CONUS looks real...it's the duration that is the question...the longer the duration, the more likely it is that we will be affected locally. Initially, we are a bit shielded from the warmer weather, but mid-month and beyond, we may not be if we don't see a flip.

 

What about the typhoon recurving in the Philippines? Usually 6-10 days later the pattern changes to colder temperatures in the eastern US. Also, this interesting post by Andrew. http://theweathercentre.blogspot.ca/2014/11/encounter-with-polar-vortex-on-horizon.html

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The EPO would help just as much... In fact, last year was a predominantly +NAO year (just as an example)

 

2014 J0.29 F1.34 M0.80 A0.31

 

...and much of the CONUS east of 100W was well below normal -- the EPO dominated.   

 

Let's not get into that trap of being NAO happy -

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The typhoon revurving could definitely screw with model guidance a bit...same with MJO if it's effects are being under-forecasted.

 

But recurving typhoons don't always mean cold for us...but if it disrupts the recovering PV, then it could help change the pattern. One reason I really want to wait until next week to assess whether we are waiting another 3 weeks or not for a regime shift back to a cold CONUS.

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The EPO would help just as much... In fact, last year was a predominantly +NAO year (just as an example)

2014 J0.29 F1.34 M0.80 A0.31

...and much of the CONUS east of 100W was well below normal -- the EPO dominated.

Let's not get into that trap of being NAO happy -

Absolutely true. But in a pacific dominated conus pattern, NAO could save us. Long term I tend to agree that. EPO is of higher priority.

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Yeah let's ease off on the cancel December and cancel winter posts. It's a bit ridiculous..and actually we look like we can sneak out an event this weekend and again days 9-10

I'd say that's marginal at best for anyone outside of NNE, don't really see a viable scenario right now where you and SNE can get anything worth noting. Probably the same areas that do well tomorrow will do the best this weekend. 

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The typhoon revurving could definitely screw with model guidance a bit...same with MJO if it's effects are being under-forecasted.

 

But recurving typhoons don't always mean cold for us...but if it disrupts the recovering PV, then it could help change the pattern. One reason I really want to wait until next week to assess whether we are waiting another 3 weeks or not for a regime shift back to a cold CONUS.

Yeah according to Larry Cosgrove tropical storm Hagupit is moving more west than prognostics would say.

http://www.ssd.noaa.gov/PS/TROP/floaters/22W/imagery/rgb0.gif

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The EPO would help just as much... In fact, last year was a predominantly +NAO year (just as an example)

 

2014 J0.29 F1.34 M0.80 A0.31

 

...and much of the CONUS east of 100W was well below normal -- the EPO dominated.   

 

Let's not get into that trap of being NAO happy -

 

Yeah the EPO can solve a lot of problems...but...

 

I think part of the reason the -NAO is more important in El Nino (esp December) is because we are more likely to have a GOA trough...we had a monster ridge there last year that poked stright up into the EPO domian. So with a GOA trough, even if there is EPO ridging north of AK, the cold delivery needs an extra push south...with a +NAO, that push isn't there. Of course, we tend to talk about these things as if they are all independent when they really aren't.

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Is the NAO supposed to stay positive throughout December? Can anyone really know how long before it changes? I thought it was one of those more fickle features of the weather, prone to change more often than say the PNA. 

 

The predictions for the AO turning negative during mid/late December are essentially unanimous among the forecasters here, and with a negative AO comes a higher probability for a negative NAO as well.  The stratospheric vortex has split (good), but the vertical wave propagation needed to sustain or amplify that process has basically stopped, which is bad.  In the near term, there is some hope that a typhoon in the west Pacific will contribute in a favorable way to the tropospheric pattern and help force a cold shot into the eastern CONUS, but hemispheric scale changes will take more time.

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