Winter Pattern Discussion 2014-2015 (December/January)

[John1122]

Now back to a less strong but colder system for Friday night-Saturday timeframe. MRX has me at a 50 percent chance of snow Friday night and thinks most areas north of 40 will see light snow into Saturday morning.

 

They are forecasting rain showers for most areas Wednesday now, though probably snow showers in the mountains and SW VA. GFS seems to support snow showers for all during that time frame.

[John1122]

The long range GFS was once again winter porn. Heavy snow cover and subzero cold showing up across the Tennessee Valley areas. Still a ways out but the upper level pattern is looking very nice. It was January 7th last year when we finally broke out of the warm December pattern and winter landed on us with both feet.

[John1122]

Long way out and with grains of salt, but this is similar to what the GFS started showing around this time last year for the early 2014 time frame. 

 

 

 

[jaxjagman]

The long range GFS was once again winter porn. Heavy snow cover and subzero cold showing up across the Tennessee Valley areas. Still a ways out but the upper level pattern is looking very nice. It was January 7th last year when we finally broke out of the warm December pattern and winter landed on us with both feet.

Yeah and a big 1044 diving down from Canada,been waiting on one of those

[Carvers Gap]

Speaking of cold, the 6z GFS still depicting a nice cold outbreak after Christmas. 0z Euro still one foot in and one foot out. Last winter the GFS rules the Euro. The weeklies were good as well. How are the weeklies? The CPC NAO ensemble from yesterday was going sharply negative, more so the AO. Winter seems to be on its way in an ever hurrying pattern. Also, looks like middle and west might get something from the Sat system per the Euro. I don't have the nice model plans some of you do. So, what does it show for the western two thirds of the state?

[tnweathernut]

Speaking of cold, the 6z GFS still depicting a nice cold outbreak after Christmas. 0z Euro still one foot in and one foot out. Last winter the GFS rules the Euro. The weeklies were good as well. How are the weeklies? The CPC NAO ensemble from yesterday was going sharply negative, more so the AO. Winter seems to be on its way in an ever hurrying pattern. Also, looks like middle and west might get something from the Sat system per the Euro. I don't have the nice model plans some of you do. So, what does it show for the western two thirds of the state?

After taking a look at last night's ensembles (GFS, Euro, GGEM) it looks like a certainty we will see something not seen in a LONG time, a -NAO.  This area has higher heights really being built on all ensembles between 144 and 168.  

 

The western ridging really starts to pop shortly after this time frame and ALL ensembles have a pretty nice look around hours 204-228.  As Carver's said, we seem to be reeling this pattern change closer.

 

All in all, I am very hopeful of one or two good systems to track as we head out of Christmas and into the New Year, and I am also hoping this type of a look can lock in and be the predominant pattern through January and February.  That part will remain to be seen at this point, but analogs say January and February should be eventful.

[jaxjagman]

Nothing much gonna happen in Mid Tn. by the looks,we might even be in the 60's Tuesday then possibly some snow Wed,with the lower level temps right now that should also be a question ?But good signs towards the end of the month like mentioned above we are fixing to head into a negative EPO/NAO/AO,the PNA is going back and forth.The PV looks like it's gonna get hit from a wave 1 attack stronger than the one in Nov coming up.

[tnweathernut]

Nothing much gonna happen in Mid Tn. by the looks,we might even be in the 60's Tuesday then possibly some snow Wed,with the lower level temps right now that should also be a question ?But good signs towards the end of the month like mentioned above we are fixing to head into a negative EPO/NAO/AO,the PNA is going back and forth.The PV looks like it's gonna get hit from a wave 1 attack stronger than the one in Nov coming up.

Hope it ends up splitting, but even if it doesn't I think we are headed toward a pretty nice period that holds potential for the TN Valley.  

[jaxjagman]

 

DT

[Mr Bob]

After taking a look at last night's ensembles (GFS, Euro, GGEM) it looks like a certainty we will see something not seen in a LONG time, a -NAO.  This area has higher heights really being built on all ensembles between 144 and 168.  

 

The western ridging really starts to pop shortly after this time frame and ALL ensembles have a pretty nice look around hours 204-228.  As Carver's said, we seem to be reeling this pattern change closer.

 

All in all, I am very hopeful of one or two good systems to track as we head out of Christmas and into the New Year, and I am also hoping this type of a look can lock in and be the predominant pattern through January and February.  That part will remain to be seen at this point, but analogs say January and February should be eventful.

So the big question is, does it lock in? The latest batch of Euro weeklies says no, but definitely want to see it back it up early next week before putting any faith in that...In the meantime...hopefully we can get something interesting the week after Christmas!

[jaxjagman]

2pm EST December 19: NOAA is experiencing a large data outage that is affecting all American models including the GFS, NAM, GEFS, and GEPS. The ECMWF, CMC, JMA, and NAVGEM are unaffected.

3:00pm EST: Apparently the backup server also has problems. The 18z NAM is late, implying problems will continue until further notice. 18z GFS may fail to come in entirely. All depends on when NOAA fixes these data issues.

[jaxjagman]

I'll post text if it dont come in for yall at the end of the run,let me know

[tnweathernut]

Technically this is part Dec and Jan pattern discussion. Might want to start a new thread or change the title of the current one sometime around or before Christmas.....JMO

[jaxjagman]

https://www.aer.com/science-research/climate-weather/arctic-oscillation

[jaxjagman]

Technically this is part Dec and Jan pattern discussion. Might want to start a new thread or change the title of the current one sometime around or before Christmas.....JMOImageUploadedByTapatalk1419027093.678176.jpg

Or get Carver to just change  this to the winter thread,just a thought

[John1122]

If editable, just changing it to a winter 2014-15 thread seems reasonable.

 

The major cold seems to be gaining momentum for January. I really hope it doesn't get as cold as last year unless it's following a snow event like the mid 60s, late 70s, 1985, 1996 major cold outbreaks. Last year we had minor snow fall, generally an inch or two or less for most of the Valley followed by the ice boxing. 

[jaxjagman]

 

[jaxjagman]

NCEP Operational Status Message
Fri Dec 19 22:23:14 2014 GMT

NOUS42 KWNO 192223
ADMNFD
SENIOR DUTY METEOROLOGIST NWS ADMINISTRATIVE MESSAGE
NWS NCEP CENTRAL OPERATIONS COLLEGE PARK MD
2215Z FRI DEC 19 2014
STATUS UPDATE ON NCEP FTP SERVER AND NOMADS
Overnight, NCEP NCO experienced an issue with our primary NCEP
ftp server and NOMADS systems.  While we are addressing that
issue, we have moved our operations to our backup systems in
Boulder.  The Boulder ftp and NOMADS systems are a degraded
backup at this time, and the additional load of the parallel
datasets is impacting our ability to disseminate our production
data through these systems.
Therefore, we are suspending the dissemination of parallel output
data from the following models for the ftp server and NOMADS.. :
GFS
Global and Hurricane Waves
Great Lakes Wave
Air Quality System
The expectation is this data will be unavailable for the entire
weekend.  We will extend the evaluation periods of the models
currently in their 30-day evaluation.
Please note that imagery from many of these parallel models,
including the GFS, will continue to be available at
http://mageval.ncep.noaa.gov/ throughout the weekend.
NEWBY/SDM/NCO/NCEP

[John1122]

The parallel overloaded the system with it's super weenie runs.

[jaxjagman]

The parallel overloaded the system with it's super weenie runs.

It hasn't been very super,has a worse score than the GFS

[tnweathernut]

[Carvers Gap]

0z 12 GFS continues to show cold moving into the Tennessee Valley just after Christmas.

[1234snow]

Haven't looked at the CFS2 in a long time and figured I would check it out. It shows wall to wall cold(below average) temps for the entire month of January.

Dec. 24th - January 3rd:

Dec. 29th - January 8th:

Jan. 3rd-13th:

Jan. 8th-18th:

[1234snow]

Here is the rest of the month from the CFS2:

Jan. 13-23rd:

Jan. 18-28th:

Jan. 23-Feb. 2nd:

Now I know this model isn't the best out there. It failed to see the cold November until just a few days before the month started (last couple of days in October) but it did finally latch on. I recall this model also had December looking fairly warm from runs at the end of November.

I think this model can be a good tool as we get toward the end of December and closer to January but I think it is a good sign that there is no warmup at all for the whole month(very unlikely to happen) being shown on the model right now.

[1234snow]

As for precip on the CFS2 it was slightly below average for the whole month.

[Carvers Gap]

The CFS2 has, IMO, been a pretty suspect model this winter. Seems to have a very warm bias. The only way I have been able to use it is to look at the way it is trending. In early December, it had January as warm but was trending cooler.

The 0z Euro is now dropping a trough into a large portion of the country. So much so, the Gulf states might have a chance at snow. Would be a very suppressed pattern. Yet another solution. Still, looks like the overall pattern getting cold right after Christmas and majorly cold at the new year. As Robert mentioned, could be warmth over the top in northern Canada and cold below. My concern with that is that that the pool of cold air "dries" up and is unable to be resupplied by that blocking pattern. Basically, we get three weeks of cold with the air mass stagnating through time. Then things go zonal, and it begins to be tough to get cold delivered. Still, lots to play out. While it may not be as severe a winter as many predicted, looks like at the very least we will have window during the coldest time of the year by averages. With Nino energy pushing against the west side of the trough, something has to give.

On a side note, the West coast should get some much needed rain.

[GaWx]

Well, so much for the warm CFSv2 Jan fcast. It has solid cold in the E US now and the coldest anomalies on the planet. 1939-40 type winter still possible based on this!

Day by day evolution of Jan fcast as it got colder over last week:

http://www.cpc.ncep.noaa.gov/products/people/mchen/CFSv2FCST/monthly/images/summaryCFSv2.NaT2m.201501.gif

It also has drier than normal for the SE outside of SE GA and FL though it often takes only one major winter storm to make it a memorable winter for much of the SE US and cold is much more crucial than wet based on history. Example: Feb. of 1895 was quite dry in ATL with only 2". Yet, it is the snowiest month in ATL history with 11.6" from three storms!

http://www.cpc.ncep.noaa.gov/products/people/mchen/CFSv2FCST/monthly/images/summaryCFSv2.NaPrec.201501.gif

[tnweathernut]

My concern with that is that that the pool of cold air "dries" up and is unable to be resupplied by that blocking pattern. Basically, we get three weeks of cold with the air mass stagnating through time. Then things go zonal, and it begins to be tough to get cold delivered. Still, lots to play.

I agree on lots to play out. Thanks for your post Carvers and others.

Not so sure about cold that stagnates. If we pop a Rex block into Alaska (as shown on the ensembles), there is a chance cross polar flow gets involved. That would likely mean multiple pushes of very cold air to our side of the planet over several weeks.

I am not sold on a blocking -NAO at this point and think it builds nicely (as shown) and then wanes toward neutral. I don't tink it ever connects over the top. Where it goes from the nice negative modeled is anyone's guess. It's not been helpful in years it seems so who knows? It's possible it comes back strong later in January/Feb I suppose......

But the period I am most interested in is right in front of us. A GREAT look during a prime time. Lets score a touchdown before looking for the next one, or worrying about where we go after the cold comes. Just last year the models kept screaming warmup, only to continue the arctic invasions. Could happen again I suppose . We do have a monster +PDO.

Let's see how it plays out and enjoy the ride, whatever it brings us. Have a great weekend everyone, but you might want to stay out of the SE thread. I tried to bring optimistic cheer to their thread yesterday, but there are many cliff divers...

Kind of funny. Since it's not really been winter yet...

[GaWx]

Regarding today's CFSv2, it has as mentioned the coldest anomalies on the planet in the E US with a whopping 3-4 below C or 5.4-7.2 below F for a good portion of the SE! That is quite an anomaly, especially considering the start of Jan is still 12 days away.

[Carvers Gap]

I think many folks remember the non-winters of the 90s. Might be why many get nervous, that and our latitude. Rarely do we get snow before Christmas in Kingsport of any major significance. Seems like a winter forecast is such a difficult task when a La Niña or Niño is not raging. I don't usually throw in the towel until February. Many winters have been saved in February. So, we have a solid 10 weeks before things move to spring. I think last January spoiled folks with almost wall to wall cold. El Niño winters, not matter what the strength, are often wet and chilly. The strength of the Niño defines the precip type. The lack of snow cover in Canada does concern me some,but that can change quickly. Things can and will change quickly here as well. It is winter. I would be completely shocked if many don't cash in on this. May just be this winter is one of a few big events instead of several small ones.