Winter 2014-2015 Pattern Discussion Thread I

[Cold Rain]

D10+ on the 12z GFS is cool with a dry NW flow.  PNA ridge is too far east, but it does not line up with the latest CFS Dec forecast...AT ALL (I know the CFS is looking at the whole month).

[Amos83]

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

 

Agreed, I am perfectly fine with a 2 week or so relaxation of the patter to happen the first half of December, then when the pattern unloads again it will be just in time for Christmas and the first of the New Year. I haven't seen much to get concerned about for this winter, November was a bonus IMO  

 

Time for panic is not here folks. There is and will be a ton of very cold air in Canada building up which is eventually get unleashed into the US. just got to be patient

[Cold Rain]

Mr...

 

 

 

 

...just made a nice post in the main forum about the CFS and December.  Seems to pretty much echo the consensus.

[Southern Track]

Love seeing that extremely +PNA showing up today on the teleconnections. Even better is Don debunking the CFS.

[mackerel_sky]

Mr...

Donald.jpg

...just made a nice post in the main forum about the CFS and December. Seems to pretty much echo the consensus.

Link? Thanks

[LithiaWx]

Link? Thanks

 

 

 

If one looks at the latest CFSv2 forecast for December, one finds a “torch-type” outcome across virtually all of North America. Such an outcome would be enough to steal all the joy associated with Hanukkah and Christmas. However, the latest teleconnection forecasts suggest the development of a PNA+/AO- regime in the longer-range.

 

 

Such an outcome would favor the development of a trough in eastern North America with associated cold anomalies in that area. The latest run of the GFS ensembles shows the possible development of such an outcome at the end of its range. The just-completed 11/26/2014 12z run of the GFS also hints at a return to cooler conditions in the extended range.

 

 

All said, I remain wary of the CFSv2 idea given the forecast teleconnections and 500 mb pattern. Moreover, it should be noted that even the 10/31 run of the CFSv2 showed warm anomalies across almost all of North America for November. To put it mildly, even as sleet is pinging in parts of the NYC metro area and snow is falling not far outside the city, November has worked out differently. Therefore, my guess is that a colder pattern could begin to develop toward or just before mid-month.

[NC_hailstorm]

Earthlight had a great post over on one of the other subforums. Now, granted, this applies to the northeast but there's no reason it couldnt help us: 

http://www.americanwx.com/bb/index.php/topic/44994-rising-confidence-in-favorable-period-for-snow-dec-15-jan-1/

Good to see people looking at the stratosphere more for clues,this was once considered voo doo stuff around here 5 years ago.

 

Only concern I have now is we hit solar max today on the 87 day average right at 150,how that interacts with a very negative QBO.Data suggests ridge in the SE but we'll see we have other good signals.

[pcbjr]

Good to see people looking at the stratosphere more for clues,this was once considered voo doo stuff around here 5 years ago.

 

Only concern I have now is we hit solar max today on the 87 day average right at 150,how that interacts with a very negative QBO.Data suggests ridge in the SE but we'll see we have other good signals.

 

Let's hope for "but" ...

 

 

[packbacker]

Mr...

Donald.jpg

...just made a nice post in the main forum about the CFS and December. Seems to pretty much echo the consensus.

Good read but what in the world does it take to get a winter time -NAO. It's been 4 years since we have a had a sustained -NAO. It's been so long I forgot how the bloody thing works!

[Cold Rain]

Good read but what in the world does it take to get a winter time -NAO. It's been 4 years since we have a had a sustained -NAO. It's been so long I forgot how the bloody thing works!

I hear you. Seems like it's a wintertime unicorn. I can't even remember the last time I even saw a good Greenland block modeled in fantasy land. Even so, according to everything that's been suggested, this is the year for it: Big negative and ascending QBO, excellent SST configuration, building El Niño, big SAI, big SCE, Al Marinaro's research, etc. In fact, the only things that I can see against are maybe solar and long range guidance and climate models. Based on what's been suggested, we shouldn't start really seeing it until later on in December. So we have time yet before having to worry.

All the same, the next couple of weeks at least look hostile toward cold, snow, and winter fun, as the pattern aligns against us....hence my signature.

[superjames1992]

Good read but what in the world does it take to get a winter time -NAO. It's been 4 years since we have a had a sustained -NAO. It's been so long I forgot how the bloody thing works!

 

Considering the lack of -NAO since 2010, we've done pretty well for ourselves over the last few winters, TBH...

 

I guess we had to make up for the super -NAO in 2009-2010.

[Snowless in Carrollton]

Considering the lack of -NAO since 2010, we've done pretty well for ourselves over the last few winters, TBH...

I guess we had to make up for the super -NAO in 2009-2010.

Lets not forget that we also had probably the 2 warmest winters in any of our lifetimes also in the last 3 winters.

[CAD_Wedge_NC]

Looks like a possible over-running event early next week. Freezing rain for the damming areas? Got a strong high in a good position and a cold source region. QPF is light, but hey, it's something to keep an eye on.

[GreensboroWx]

Looks like a possible over-running event early next week. Freezing rain for the damming areas? Got a strong high in a good position and a cold source region. QPF is light, but hey, it's something to keep an eye on.

 

Yes, the models have been steady showing a strong CAD signature for several runs in a row next Wed. Precip looks light but it is something to watch....

[Marion_NC_WX]

Big shocker here...another really strong surface high coming down by Day 4...that's the same high that slides east and creates the CAD setup that you guys are talking about for next week. It's unfortunate that there's nothing at 500mb that could create a temporary road block or I think we would be talking a much stronger and deeper potential CAD. But as it currently is, it should still be decent and could be an issue on P-types in VA to far northern NC.

 

 

 

 

[GaWx]

Big shocker here...another really strong surface high coming down by Day 4...that's the same high that slides east and creates the CAD setup that you guys are talking about for next week. It's unfortunate that there's nothing at 500mb that could create a temporary road block or I think we would be talking a much stronger and deeper potential CAD. But as it currently is, it should still be decent and could be an issue on P-types in VA to far northern NC.

It varies with the model but there really isn't a longlasting period of warmth on many of the runs of various models though the 6Z GFS went back to warmth in the 11-15. Even the 6Z GEFS disagrees strongly with its op. and has a pretty stout +PNA for the 11-15 with slightly below normal temperatures. The 0Z Euro ens. is slightly above for the 11-15. Quite noteworthy is the 0Z CMC ens. It has a very stout +PNA and solid below normal temp.'s for the 11-15. What's especially noteworthy about that is that the CMC ensemble tends to be warm biased, especially in the 11-15. So, in summary, there's still lots of disagreement as well as lots of changes between runs in some cases. However, there is reason to believe that a pretty quick change back to colder is a very realistic scenario though probably in step-down fashion. Regardless, based on analogs and other things, I will remain unworried about the prospects for a cold winter as long as, say, two weeks or so from now models don't look solidly warm out two weeks, which they don't even do now.

Happy Thanksgiving to all

[WidreMann]

We can agree that the OP Euro looks awful, though.

[GaWx]

We can agree that the OP Euro looks awful, though.

It depends on how you look at it. The more reliable 6-10 is not warm at all as a whole and is cooler than most models. This includes its ensemble mean. However, the end of the 6-10 and the associated 11-15 Euro ens mean is warm. Then again, the 11-15 is much less reliable than the 6-10 and it is much warmer than both the GEFS and CMC for the 11-15. So, I don't know how to consider that. It is a bit confusing.

[Carvers Gap]

It depends on how you look at it. The more reliable 6-10 is not warm at all as a whole and is cooler than most models. This includes its ensemble mean. However, the end of the 6-10 and the associated 11-15 Euro ens mean is warm. Then again, the 11-15 is much less reliable than the 6-10 and it is much warmer than both the GEFS and CMC for the 11-15. So, I don't know how to consider that. It is a bit confusing.

 

The CFS2 and Euro are pretty similar.  Warm to start the month of December.  Time will tell how quickly the pattern changes.  A weak Nino would argue towards a flip at some point.  However, the flip indeed seems to be towards a much warmer pattern in the near term when compared to November.  Probably not a torch, but above normal through mid-month it appears.

[Cold Rain]

It just indicates a non-stable/variable pattern, which is not uncommon at all. The expectation should be for neither freezing nor torching to dominate over the next two weeks.

As was pointed out, the GFS shows a 1040 high migrating through a favorable location to provide damming. I'm pretty surprised that a high of that magnitude doesn't indicate a stronger push of cold air at 850, especially given that there is no strong low messing up the thermals. Maybe the source region isn't cold enough? It's strange because usually, the models overestimate the cold press (I'm not talking about surface temps in damming scenarios here -- just the standard over-modeling of the cold).

Anyway, even in a variable pattern, something can sneak through.

[Marion_NC_WX]

It just indicates a non-stable/variable pattern, which is not uncommon at all. The expectation should be for neither freezing nor torching to dominate over the next two weeks.

As was pointed out, the GFS shows a 1040 high migrating through a favorable location to provide damming. I'm pretty surprised that a high of that magnitude doesn't indicate a stronger push of cold air at 850, especially given that there is no strong low messing up the thermals. Maybe the source region isn't cold enough? It's strange because usually, the models overestimate the cold press (I'm not talking about surface temps in damming scenarios here -- just the standard over-modeling of the cold).

Anyway, even in a variable pattern, something can sneak through.

 

 

 

 

For sure this next surface high isn't tapping into a cross-polar flow by any means but the cold in Northern North America (a result of snow pack thanks to the recent cross-polar influx) makes this next airmass cold enough to be very respectable.

 

This all goes back to my original statement that we need some kind of 50/50 low in the 500mb flow to slow things down a little. What's happening as a result is that the surface high never has a chance to really establish itself before moving on. You could see it in panels on the 6z run, the CAD was building in good for VA and was bound for North Carolina  between hours 114-120 but due to the fast, transient flow, that surface high is already departing on the next frame and the winds begin to veer again.

 

BTW, while I'm typing this, I'm looking at the new run (12z), it has a 1044 mb high over Southern Ontario @120 with the wedge building...but then departing on the next frame.

 

Trust me, if I had a 1044 mb high in Southern Ontario and it stuck around for 18-24 hours, I would be getting really excited.

[LithiaWx]

It just indicates a non-stable/variable pattern, which is not uncommon at all. The expectation should be for neither freezing nor torching to dominate over the next two weeks.

As was pointed out, the GFS shows a 1040 high migrating through a favorable location to provide damming. I'm pretty surprised that a high of that magnitude doesn't indicate a stronger push of cold air at 850, especially given that there is no strong low messing up the thermals. Maybe the source region isn't cold enough? It's strange because usually, the models overestimate the cold press (I'm not talking about surface temps in damming scenarios here -- just the standard over-modeling of the cold).

Anyway, even in a variable pattern, something can sneak through.

Great post man, the euro weeklies agree to all of this.

[dsaur]

It varies with the model but there really isn't a longlasting period of warmth on many of the runs of various models though the 6Z GFS went back to warmth in the 11-15. Even the 6Z GEFS disagrees strongly with its op. and has a pretty stout +PNA for the 11-15 with slightly below normal temperatures. The 0Z Euro ens. is slightly above for the 11-15. Quite noteworthy is the 0Z CMC ens. It has a very stout +PNA and solid below normal temp.'s for the 11-15. What's especially noteworthy about that is that the CMC ensemble tends to be warm biased, especially in the 11-15. So, in summary, there's still lots of disagreement as well as lots of changes between runs in some cases. However, there is reason to believe that a pretty quick change back to colder is a very realistic scenario though probably in step-down fashion. Regardless, based on analogs and other things, I will remain unworried about the prospects for a cold winter as long as, say, two weeks or so from now models don't look solidly warm out two weeks, which they don't even do now.

Happy Thanksgiving to all

I was out doing yard work, then hanging lights on the pole barn, and the low 40's with clouds and a breeze, felt and looked like winter.  A good Thanksgiving day to me, cold and cloudy...just right!  The only thing to mar it was the sun coming out occasionally. Wouldn't surprise me at all to seething frozen in Dec   Like Carrollton said, we've seen some torch winters lately, and no way this one is shaping up to be as bad. Especially if it rains.   Happy Tday to you, and to all.  T

[packbacker]

The Euro ENS highly supports the CFS through the first 12 days of Dec. It's spring time in North America.

[pcbjr]

The Euro ENS highly supports the CFS through the first 12 days of Dec. It's spring time in North America.

Thanks. I just did something with turkey as I checked this out ... (well never mind - being hailed back to the table).

 

My reaction - just about as bad as the EURO, CFA & GFS & ..... outlook.

 

Interesting though - getting my 4th below 32 this fall tonight, which will exceed 10 nights in the 30s so far.

 

Always had concerns about early cold ....

[GaWx]

I was out doing yard work, then hanging lights on the pole barn, and the low 40's with clouds and a breeze, felt and looked like winter.  A good Thanksgiving day to me, cold and cloudy...just right!  The only thing to mar it was the sun coming out occasionally. Wouldn't surprise me at all to seething frozen in Dec   Like Carrollton said, we've seen some torch winters lately, and no way this one is shaping up to be as bad. Especially if it rains.   Happy Tday to you, and to all.  T

 

Tony/all,

 Happy Thanksgiving. As I said, I looked at Nov. rainfall vs. DJF rainfall at KATL. The first column is Nov. rain. The 2nd-4th are the percentages of DJF that were dry/near normal/wet. Dry is under 11.5" while wet is 16"+. The size of the sample is large, 135 years.

 

0-2":  35%/43%/23%

2-4":  24%/39%/37%

4"+:   45%/34%/20%

 

 So, you can see from this that for the 135 year sample, the best chance for a wet DJF has been when Nov. rain is 2-4". Dry Novembers not surprisingly favor normal to dry DJF's. Interestingly, wet Novembers also favor normal to dry, which is seemingly counterintuitive.

 

 Now, I'll look at the 34 similar ENSO analogs, alone:

 

0-2": 3/5/0 38%/63%/00%

2-4": 3/4/7  21%/29%/50%

4"+:  7/2/3  58%/17%/25%

 

 This is pretty similar. If you want a wet DJF, the best bet for Nov. rain has been 2-4".

 

 Year by year of Nov. rainfall for ENSO analogs: 0.30”, 0.41”, 0.54", 1.04", 1.27", 1.35”, 1.55” 1.79”, 2.12", 2.14", 2.33", 2.35", 2.63", 2.67", 2.84", 2.92", 3.27”, 3.55”, 3.56”, 3.62", 3.81", 3.98”, 4.11", 4.17", 4.39", 4.81", 4.89", 5.19", 5.61", 6.20”, 6.26", 7.18", 7.26”, 8.21"

 

Brown = dry DJF

Black = near normal DJF

Green = wet DJF

 

 Note that no under 2" November was followed by a wet DJF, which is intuitive. It looks like Nov. 2014 will end up with 3.85". That is near the high end of the most concentrated Novembers that preceded wet DJF's though it isn't far from a group of Nov.'s that preceded dry DJF's fwiw. So, it is hard to say what a 3.85" November means except to say that that position probably isn't screaming dry DJF.

 

 Wet DJF's among ENSO analogs: 1880-1, 1884-5, 1900-1, 1914-5, 1919-20, 1935-6, 1936-7, 1951-2, 1952-3, 1963-4

 

 Note that it has been a whopping 51 years since the last wet DJF of the 34 ENSO analogs! That means that none of the last 11 ENSO analog DJF's have been wet. So, a wet one is due fwiw (in case it goes in cycles).

[deltadog03]

Well...Interesting times coming up over the next 2 weeks...What you mean, Chris?  Well, Most people, pro mets as well, have been singing a pretty good/cold/snowy winter for most of the east.  Not really the xtremes, but overall that way.  Well, this is where your homework, skill and luck come into play.  The freakin models in the longer range look pretty awful to be honest.  EURO has a nice wamr singal out to like D15 or so, from what I have seen.  So, do you start thinking, well....are we going to be warm for DEC, or is it heading to bust territory like last year?  Just some random thoughts.  I personally think we are in for a nice winter.  We always get warm, to be honest, I would rather it happen in early DEC vs late. 

[pcbjr]

The last 2 days the 18Z GFS has been way out there suggesting cold in the LR (only model run I've seen, at least, to do that). Looks like today's 18Z has gotten through with its eggnog and other libations binge and is back on the wagon.

 

[packbacker]

Well...Interesting times coming up over the next 2 weeks...What you mean, Chris? Well, Most people, pro mets as well, have been singing a pretty good/cold/snowy winter for most of the east. Not really the xtremes, but overall that way. Well, this is where your homework, skill and luck come into play. The freakin models in the longer range look pretty awful to be honest. EURO has a nice wamr singal out to like D15 or so, from what I have seen. So, do you start thinking, well....are we going to be warm for DEC, or is it heading to bust territory like last year? Just some random thoughts. I personally think we are in for a nice winter. We always get warm, to be honest, I would rather it happen in early DEC vs late.

04/05 is a viable analog, weak nino with +PDO for the winter, QBO doesn't match up, but ....

Also, 04/05 had the -AO in Oct which some people think it leads to a -AO in DJF, which didn't happen. I guess Feb was negative. Big old +AO for 04/05 too. This past Oct had -AO.

[pcbjr]

04/05 is a viable analog, weak nino with +PDO for the winter, QBO doesn't match up, but ....

 

Also, 04/05 had the -AO in Oct which some people think it leads to a -AO in DJ, which didn't happen.  I guess Feb was negative.  Big old +AO for 04/05 too.  This past Oct had -AO.