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Winter 2014-2015 Pattern Discussion Thread I

LithiaWx

By LithiaWx,
in Southeastern States

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Cold Rain

Cold Rain

Posted
Posted

I didn't see or follow every local forecast around here, but the ones I did never forecast Atlanta to be higher than 70 today so I was also kinda caught by surprise when I saw we broke a record high by reaching the upper 70s today.

Ok, good deal. It takes a big man to admit when he's wrong. I am not a big man.

JK. Sorry Max. My mistake this time.

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FallsLake

FallsLake

Posted
Posted

Well, the pattern sucks as far as the eye can see on all of the operational models. And the CFS continues to scorch the winter. Canada stays cold, though, on all accounts.

At least the (6z)GFS is not a total torch. It does show cool downs every few days and it looks like the pattern would be getting better towards the end (but that is day 16..).

http://mag.ncep.noaa.gov/Image.php?fhr=384ℑ=data%2Fgfs%2F06%2Fgfs_namer_384_850_temp_mslp_precip.gif&model=gfs&area=namer&param=850_temp_mslp_precip&group=Model+Guidance&preselected_formatted_cycle_date=20141125+06+UTC&imageSize=M&ps=model

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Southern Track

Southern Track

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Looking at the Indeces this morning it looks like the AO goes negative short term and looks to stay there through the first week of December while the NAO trends toward neutral the end of the first week of December. The PNA looks to go positive towards the end of the first week of December.

No scientific analysis necessarily but it has been a rarity for the PNA to be negative since the first of August with a mean of .5434 so I hope to see that pattern continue the next few months.

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CherokeeGA

CherokeeGA

Posted
Posted

I didn't see or follow every local forecast around here, but the ones I did never forecast Atlanta to be higher than 70 today so I was also kinda caught by surprise when I saw we broke a record high by reaching the upper 70s today.

 

We are usually 5-7 degrees cooler than the official KATL temps up here.  Even we reached 73 yesterday.  At least 10 degrees higher than I expected.  Not the first time we have gone way over forecast temps this year, though.

 

I didn't want to turn the AC back on, but our upstairs was over 80... so we opened all the windows and put books on everything we didn't want to fly away, the strong breezes did a nice job airing out the house!

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LithiaWx

LithiaWx

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Looking at the Indeces this morning it looks like the AO goes negative short term and looks to stay there through the first week of December while the NAO trends toward neutral the end of the first week of December. The PNA looks to go positive towards the end of the first week of December.

No scientific analysis necessarily but it has been a rarity for the PNA to be negative since the first of August with a mean of .5434 so I hope to see that pattern continue the next few months.

 

 

I agree on the PNA going positive, that looks very, very likely. 

 

OTOH - The AO and NAO look like they could go either way.  looks like a pretty even split on where it could end up in this time frame 50/50.

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Cold Rain

Cold Rain

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I agree about the PNA as well. The tendency has been (and I believe will continue to remain) positive. The same with the AO, except in reverse. It has had a tendency to be somewhat negative, so I would err in that direction. Big forecast rises have been muted. The wildcard is the NAO, which has oscillated on either side of neutral lately. I agree with Burger (and as others have stated) that somewhere around the midway point of December, give or take a few days, we start stepping down.

By the way, the index graphs are nice to look at, but the 500mb charts on at least the operational runs do not look good for much cold or winter prospects. Like Falls said, a non torchy pattern is the most likely outcome. It just looks simply seasonal.

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packbacker

packbacker

Posted
Posted

Well, the pattern sucks as far as the eye can see on all of the operational models. And the CFS continues to scorch the winter. Canada stays cold, though, on all accounts.

 

This is like a major torch for Dec on the CFS, I have never seen it that torchy for a winter month...ever.  I know it was terrible with Nov's forecast but it's usually not a huge miss every time.  It did fairly good with each month last winter.  We still have 6 days of the month left so it could still flip to neutral/cool/cold in the next week for Dec.

post-2311-0-28767200-1416930445_thumb.pn

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packbacker

packbacker

Posted
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How well does the CFS verify? It never seems to do very well.

It does fairly good at the monthly forecast once it gets closer to end of the month. So the runs for Dec on Nov 28-30th will be telling. It did very well last winter.

It did bust for Nov but so did the short range ensembles of Euro and GFS.

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wncsnow

wncsnow

Posted
Posted

Has anyone else noticed that the CFS seems to have trouble differentiating the current pattern to the future one? When there is cooler than average temps across the SE forecasted for the upcoming week I have noticed the outlooks tend to show below average for the following months, and vice versa. The pattern we are about to enter is generally warmer than average for the next week or 2 that looks fairly certain, but does the CFS really do a good job looking past that?

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packbacker

packbacker

Posted
Posted

The CFS monthly, not the seasonal, nailed last winter...it will miss from time to time but all in all it's done good.  For this past fall, it did miss Nov but did hit Sept/Oct.  I went back and looked at the past 3 winters, it missed Jan 2013, but for the other winter months it did pretty good.  The CFS monthly may flip for Dec too, it has 6 more days of model runs.

 

I am fairly certain JB is talking about the seasonal CFS.

 

Edit:  Maybe the CFS struggles with nino/+PDO setups, we haven't had one in a while.

post-2311-0-28298000-1416937437_thumb.pn

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FallsLake

FallsLake

Posted
Posted

6z GFS really sucks in the LR if your looking for cold and wintery weather. Most of the cold air stays locked up in Canada and even at day 16 doesn't show any signs of breaking. The one good thing is it doesn't look to torch. There are many days that look like there could be cool CAD setups or at least N/NE winds (from a Pacific originated air mass). **better to have temps in the 50s than 70s.

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GaWx

GaWx

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Although the ensemble means are mixed regarding whether or not warmth remains in the SE for December week 2 (GEFS and CMC near to below normal and Euro near to above normal), the Euro and GEFS are still calling for a -AO to reappear within a couple of days and to dominate into early December. IMO, though it isn't at all crucial it get cold dominated again before mid December, it is pretty important that December's AO end up negative for the month as a whole to give me the feeling that Judah Cohen's SAI theory will work out for this winter as a whole. It doesn't have to be strongly negative though I do feel that a strongly -AO this December would be quite encouraging for obvious reasons.

The thing that will need more work would be getting a -NAO for December. Though not as crucial IMO to get it early, it would also be encouraging if there could be a -NAO for December as a whole. Regardless, if we do end up with a solid -AO for this DJF averaged, it would be quite surprising if a pretty solid -NAO averaged over DJF were to not occur. I'm still as pumped as ever for this winter.

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packbacker

packbacker

Posted
Posted

Although the ensemble means are mixed regarding whether or not warmth remains in the SE for December week 2 (GEFS and CMC near to below normal and Euro near to above normal), the Euro and GEFS are still calling for a -AO to reappear within a couple of days and to dominate into early December. IMO, though it isn't at all crucial it get cold dominated again before mid December, it is pretty important that December's AO end up negative for the month as a whole to give me the feeling that Judah Cohen's SAI theory will work out for this winter as a whole. It doesn't have to be strongly negative though I do feel that a strongly -AO this December would be quite encouraging for obvious reasons.

The thing that will need more work would be getting a -NAO for December. Though not as crucial IMO to get it early, it would also be encouraging if there could be a -NAO for December as a whole. Regardless, if we do end up with a solid -AO for this DJF averaged, it would be quite surprising if a pretty solid -NAO averaged over DJF were to not occur. I'm still as pumped as ever for this winter.

 

It's nice to see all the global ensembles bring back the low over the Aleutians.  But, the stratosphere plots suck, the idea of the early Dec SSW isn't going to happen, let's hope it we can get some warming going at the end of December.  I am with you though, just want to see the -AO in Dec, regardless of whether we (SE) are cold.  The analogs for +AO Dec Nino's doesn't bode well for the rest of the winter.  

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GaWx

GaWx

Posted
Posted

It's nice to see all the global ensembles bring back the low over the Aleutians.  But, the stratosphere plots suck, the idea of the early Dec SSW isn't going to happen, let's hope it we can get some warming going at the end of December.  I am with you though, just want to see the -AO in Dec, regardless of whether we (SE) are cold.  The analogs for +AO Dec Nino's doesn't bode well for the rest of the winter.

Pack,

Don't forget that a SSW is not at all necessary to allow for a very strong -AO. Only half of the sub -2 AO months (6 of 12) since the late 70's had an associated SSW. If I were you, I wouldn't get too hung up on whether or not there is an actual SSW. For example, there was no SSW to cause either the 12/2009 AO of -3.413 or the 1/2010 AO of -2.587.

 

Supporting evidence:

 

- 1/1980: -2.066;  no SSW found

- 1/1985:-2.806;  SSW found

- 2/1986: -2.904;  SSW found in 1/1986

- 2/1995: -2.127; no SSW found

- 1/1998: -2.081; SSW found in late 12/1997

- 12/2000: -2.354; SSW found

- 12/2005: -2.104; no SSW found

- 12/2009: -3.413; no SSW found

- 1/2010: -2.587; no SSW found til late Jan., which would be too late to affect most of the month

- 2/2010: -4.266; SSW found in late January 2010

-12/2010: -2.631; no SSW found

- 3/2013: -3.185; SSW found in early January (I guess that is recent enough to possibly be related)

 

 

AO's found here:

http://www.cpc.noaa.gov/products/precip/CWlink/daily_ao_index/monthly.ao.index.b50.current.ascii.table

 

SSW's found here:

http://www.cpc.ncep.noaa.gov/products/stratosphere/strat-trop/

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deltadog03

deltadog03

Posted
Posted

I think the second half of December is when we get rolling. Models still doing their usual flip flopping in the LR. I'm not stepping off the gas that I think we have a real shot at a white Christmas. Nothing scientific pushing that, just a feeling I have. 

I would say that typically lines up nicely.  2 week break and relax of pattern.

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