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Winter 2014-2015 Pattern Discussion Thread II


JoshM

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IMO Don hasn't done anything other than highlight what the models are showing as a possibility and bringing out those that are in the process of cancelling winter. Is it possible for a winter of warmth to happen..YES.....is it possible for winter to give us at least one (if not more) chances of a winter wonderland.....YES.  The point is, everything we are looking at says it should be a great winter, but for whatever reason the atmosphere is acting more Nina like than Nino at the moment.

From Don......

The latest teleconnection forecasts offer only more misery. Forecasts for a deeply negative EPO have been withdrawn almost as suddenly as they had first appeared. The PNA is now forecast to creep into negative territory.

 

What’s that immense tower in the distance? It dwarfs even the world’s tallest structure. Look closer. That’s the latest GFS ensemble forecast for the Arctic Oscillation. One member even takes the AO toward +5 during the first week in January.

 

 

 

He would be much better off & even more intelligible if he laid off the models & tried incorporating a bit more organic forecasting into his ideas, but his posts are still great nonetheless....

 

The shift in equatorial forcing into the eastern hemisphere, the oncoming upwelling intraseasonal phase of the Oceanic KW & the overall lower frequency warming of the Indian Ocean along w/ an IOD heading into negative territory are all to blame for the Nina-like atmospheric response...

28.gif

utwv.last.60.gif

 

 

iod1.png

Indian-Ocean-SSTs-Kaplan-SSTv2-1950-2014

 

wkd20eq2_anm.gif

 

 

The only favorable signal for the El Nino in the southern hemisphere specifically appears to be the Antarctic Circumpolar Wave (an eastward propagating wave (which goes against the flow of the Antarctic Circumpolar current) w/ a #2 signal expressed in part by SSTs anomalies where the strongest anomalies are found usually near 50-60S, w/ a spectral peak in it's half cycle (full cycle of ACW is 8-9 years) that's approximately in phase w/ the ENSO index (~ 4 years).

 

Southern hemisphere SST anomalies for the dominant EOF of the Antarctic Circumpolar Wave mapped every 6 months is shown below

acw.jpg

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Just to temper enthusiasm this is one run of one model. We need to see some of the other models to jump on board as well. GFS PARA not as crazy with the cold but it doesn't look bad either out to 156. PV isn't as insane. 

Yeah The run to run differences are pretty big. I wish I shared the enthusiasm some are showing but considering how the major players keep shifting hundreds of miles... (or reappearing and disappearing altogether)  from one run to the next...it makes it rather difficult. 

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Yeah The run to run differences are pretty big. I wish I shared the enthusiasm some are showing but considering how the major players keep shifting hundreds of miles... (or reappearing and disappearing altogether) from one run to the next...it makes it rather difficult.

You missed a prime Glenn burns moment last week.

Go Panthers :)

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I'll have to nail down the specific numerical teleconnection anomalies, but it's fairly clear from looking @ the 500mb patterns preceding large winter storms in the southern US, the EPO appears to contribute the largest amount of variance in the set-ups leading up to wintry weather in the southern tier, whereas the AO/NAO appears to bear less significance.

DJF-EPO-500mb-Correlation-Southern-US-Ov

 

You don't necessarily need a -NAO/AO (as shown by the Feb 1973 & Dec 1989 events) to have a major winter storm engulf the south. In looking @ some of the patterns leading up to some of the most historic storms, by & large, the primary ingredient you certainly is need undercutting in the southern branch of the jet underneath an anomalous ridge in & around Alaska & extreme northwestern North America (-EPO) and a subsequent low pressure gyre over eastern North America/southern Canada to interact w/ any incoming system (which aside from the MJO operating on relatively smaller timescales can be invigorated seasonally-interannually by certain PDO, ENSO, & QBO states). IMO, if you don't block up the flow over the northeastern Pacific & force energy to focus into the subtropical jet (-EPO) , your chances of seeing a robust winter storm throughout much of the southern tier dwindle considerably. That's not going to be the case however as we close in on early January...

 

Dec 8-10 1958

Dec-10-12-1958-Southern-US-Overrunning.g

 

Feb 6-8 1973

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

 

Feb 26-28 1980

Feb-26-28-1980-Southern-US-Overrunning.g

 

Jan 2-4 1988

Jan-2-4-1988-N-America-500mb-Southern-US

 

 

Dec 19-21 1989

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

 

Dec 1-3 2002

Dec-1-2-2002-Southern-US-Overrunning.gif

 

 

Jan 26-28 2010

Jan-26-28-2010-Southern-US-Overrunning.g

 

 

Jan 6-8 2011

Jan-6-8-2011-Southern-US-Overrunning.gif

 

Even last year, the antecedent pattern ahed of the overrunning event from about Feb 11-14 exhibited similar signatures w/ blocking over the North-central Pacific encouraging the southern branch to cut underneath & troughing downstream in the eastern US & southern Canada, although the anomalous Alaskan ridge is shifted a bit to the east of the other aforementioned storms & their associated patterns...

compday.95ynICS39L.gif

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Euro following suit with a frigid start to January.  What a difference a couple of days make.  Deja vu to last January.

 

Thinking the exact same thing. Very close to the same look. PV comes down almost to TN on this run! Only thing I don't like is that everything will be suppression city. We'll need a stout clipper to work out winter weather but we can worry about that as it gets closer. 

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I can't see 240 on the Euro yet, but at 216, wow. That's cold right there. What a turn-around today! Let's hope this holds. I looked at the GFS too. Not sure how you couldn't like that pattern. There's a winter storm threat at 120 or so and another at 216. There's more beyond that too. Not worried at all about suppression yet. Great runs today!

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I can't see 240 on the Euro yet, but at 216, wow. That's cold right there. What a turn-around today! Let's hope this holds. I looked at the GFS too. Not sure how you couldn't like that pattern. There's a winter storm threat at 120 or so and another at 216. There's more beyond that too. Not worried at all about suppression yet. Great runs today!

 

Something about 1000mb pressure in the Dakotas.   :blahblah:

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At 240, looks like a reloading with the Aleutian low moving back in with the PV already over Hudson Bay. I've totally in love with this run.  Scandinavian block in place.. may trend back into the arctic depending on how much the PV digs farther south.

 

Curious to see the strat. maps...

 

YLQbtff.gif

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Something about 1000mb pressure in the Dakotas.   :blahblah:

Lol! It's much too far northwest to matter. With confluence in SE Canada, we might start seeing a high pressure somewhere in the NE on future runs...unless of course they go back to the trough west look overnight, which is entirely possible I guess. :o

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