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Winter 2013-14 Pattern Discussion II


buckeyefan1

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I can say for certain that none of the colder trends are even hinted at in the local point and click forecasts much less the local news. So there are some significant adjustments forthcoming if this to verify. I cant remember the last time we had a below normal jan/feb? Anyone? (For the triad area)

January/February 2010.
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I know with the playoffs no one was watching but the Euro looked great over the next 7-10 days. It gives us one chance on Thursday then another one on Saturday. The Saturday event looks like it has potential. That being said it is the only model with anything on Saturday. 

I agree Saturday could be another shot. The 18z GFS does show some very light snow over NC on Saturday. Temps would be no problem.

 

gfs_namer_126_850_temp_mslp_precip.gif

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I know with the playoffs no one was watching but the Euro looked great over the next 7-10 days. It gives us one chance on Thursday then another one on Saturday. The Saturday event looks like it has potential. That being said it is the only model with anything on Saturday.

It's the only one that really has anything on Thursday either.
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Folks,

 JB tweeted this comment this evening:

 

 "Cold shot coming this week not as nasty as previous one, and not as bad as what's coming last week of the month....CO2 has nothing to do with it"

 

The much respected Don Sutherland responded this way:

 

 "Setting aside JB's extraneous comment regarding CO2--I'm not sure how it has anything to do with the possible synoptic pattern evolution--the reforecast ensembles hint at a possible strong cold shot during the last week of January. The same holds true regarding the best match teleconnection cases to date for January. In fact, the 500 mb pattern and 850 mb temperature anomalies on the reforecast ensembles at 360 hours are quite close to what the teleconnection cases for the last week of January (centered around 1/27-28) show:

 

Also, if one takes into consideration the cases during the 1981-2010 climate base period during which New York City (a proxy for the region) saw a cold shot during the first half of January in which the low temperature was 2 or more standard deviations below the January 1981-2010 average low figure, another bout of severe cold typically occurred some time during the January 25-February 5 period.

 

All said, while nothing is cast in stone just yet, the possibility of another strong Arctic shot toward the end of January is probably very much on the proverbial table."

 

 Full Don post with maps here:

 

http://www.americanwx.com/bb/index.php/topic/38386-vendor-forecast-discussion/page-23#entry2636021

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Interesting.

http://theweathercentre.blogspot.com/2014/01/stratospheric-trifecta-signals-brutally.html?m=1

This would also line up with the OPI for a polar outbreak in February. Yes the OPI didn't do very well this month, but there had to be something that caused it to fail. It did perfectly fine for November and December.

http://img690.imageshack.us/img690/6809/16k2.png

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^ Very interesting, Jon. Thanks for posting.

 

Regarding the LR, this morning's index charts from CPC indicate a mostly negative look to the AO (we seem to be in a regime opposite of December in that lately, when the ensembles show the AO going positive in the LR, that has been getting muted as we move in).  There is a very strong signal for the PNA to remain at its highest values of the winter before heading back to neutral way out in time.  And of course, the NAO looks to not be meaningfully negative anytime soon.

 

The CFS is neutral for Feb, regardging temps, and looks wetter now for a large portion of the SE.

 

Both the OP Euro and GFS (0z and 6z) look cool/cold through the period.  With no real southern stream shown, precipitation chances will be driven by northern stream systems.  Snow chances will come from vorts that are strong enough and dig enough to squeeze out precipitation.  With no meaningful blocking, the pattern will be remain progressive.  Cold shots, which could be strong, will move in and out fairly quickly.  A well-placed PNA ridge, which is possible now -- a good change from earlier in the season -- can help to create the opportunity for a more meaningful winter event.

 

As stated above, we'll need to watch for shortwaves diving south toward the region.  The latest guidance unanimously agrees that several of these will indeed occur over the next couple of weeks.  Given the inherent unknowns about the strength and track of these features and the orientation, placement, and amplitude of the PNA ridging, these systems will bear watching.  Most of them will likely pass to our north, accompanied by cold, dry shots.  Under the right circumstances, however, we could have a flizzard or two or even a light snow event, if things work out.  A more moderate storm is certainly not off the table for parts of the SE.

 

At the very least, it looks mostly below normal, and you certainly can't have snow without cold air around.  So that's at least one thing to feel good about.

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Matthew East touches briefly on the Wed/Thu system but focuses more on what might happen Fri/Sat.  The ECMWF model is much more bullish on snow chances for a large portion of the Carolinas overnight Friday into Saturday than is any other model.  However, the Canadian model also shows some snowy returns for that time period.  Give it a watch!

 

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Matthew East touches briefly on the Wed/Thu system but focuses more on what might happen Fri/Sat.  The ECMWF model is much more bullish on snow chances for a large portion of the Carolinas overnight Friday into Saturday than is any other model.  However, the Canadian model also shows some snowy returns for that time period.  Give it a watch!

 

 

 

It already looks like the 12z GFS might be catching on. Looks a lot different at 5h than the 6z did. Anytime the Euro shows something a few times in a row right in it's wheelhouse you gotta stop and look. 

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12 canadian  keeps a trough in the east and sends several shortwaves down the pipe over the next 6 days with a chance of light snow with each one it looks like. In fact, looks like there could be something wintery along the gulf coast based on the 700mb RH in the first panel below but it's hard to know for sure until the more detailed maps come out. Will be interesting to see what the rest of the run looks like.

 

12_054_G1_north@america@zoomout_I_4PAN_C

 

12_054_G1_north@america@zoomout_I_4PAN_C

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 Just looking at ATL, they get to -12 C or colder at 850 in no fewer than four different airmasses during this 1/13 12Z GFS run! That would be quite a rarity for just a 16 day period. This entire run is dominated by stupid cold. For two of those airmasses, they get down to -14 to -15 C at 850! They've already gotten down to -17 C in the frigid airmass last Tue. 1/7. If this run were to come close to verifying, we'd likely be approaching a top ten cold January for KATL and much of the SE US going back to the late 1800's. It would very likely at least be a top 15 cold one for KATL.

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It's confusing in here. Some saying GFS looks great in the long run, others saying not too exciting and more of the same?? Which is it?

 

More of same...

 

The cold on the GFS is almost entirely driven by a persistent tall PNA ridge with still no signs of a -NAO, for whatever it's worth.

 

because of this. (Actually it did look kinda blocky/-NAO at 240, but it didn't last)

 

But cold yes. 

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