Winter 2021/22 December Thread

[Mr. Kevin]

6 minutes ago, Holston_River_Rambler said:

On a side note, the 12z Euro splits the SPV at 50 mb:

 

GFS ain't having much of it:

 

Still, it is under some stress at that level. 

 

The Euro even tries hard for a split at 10mb, but doesn't quite get there. 

The ever popular 3D vortex rendering gets some hits and wobbles at the lower levels, but looks stout overall:

 

 

 

 

It would be lovely to see a split if it would make a difference for us. It would also be lovely to have a SSW event this winter

[Carvers Gap]

19 minutes ago, Holston_River_Rambler said:

I think I can see the circulation you're talking about in the post just above mine. I think it is possible that helps reinforce some ridging in the NAO area. Lots of concern with the Pac across the weather forums and rightly so, but that's a sneaky pattern you've pointed out. It will be interesting to see how it evolves. 

Past week or so we have seen an increased frequency of the AH(tired of typing Aleutian high) to lose some steam on LR modeling.  Last night,  JB mentioned the EPS may be hinting at the MJO firing.  The IO has little convection.  Need it to fire in order to push the MJO along.  Right now the maps look very much like a phase 7 which is pushing near 8.  Looks like we may potentially have a window for tracking between the 3-10 with the window between the 6-8th having the most promise.  Crazy thing, nobody remembers those great Niña winters if you subtract 10-14 days of cold during those winters.  Just need the pattern to relax which it may.  

Great discussion today by everyone!  

[Daniel Boone]

4 hours ago, Carvers Gap said:

12z CMC is better in terms of the pattern here.  Snow on the 3rd and then a cold period follows.  

It ruled the roost here irt snowfall forecast last season. However, that was at much closer range. 

   

[jaxjagman]

It STILL seems possible the Euro is going to be wrong with the MJO from destructive interference from KW

[John1122]

LaNina, if I recall correctly, usually would see more clippers and northern stream energy that gives us snow chances. 

The SOI stuff makes sense. The West is seeing Nino conditions in California. All I saw all fall was the drought was going to accelerate in So Cal due to the Nina. It's being eaten away instead.  Massive snow pack is building and the Lower elevations are getting frequent rain. 

The upper Midwest definitely isn't seeing Nina conditions either. Nor are the mountain west states. Areas from Montana to Wisconsin that would normally be well BN in a Nina are +4 to +6 this December. 

So far December temps in the area are similar to December 1984/December 2015. Both saw the patten flip in January and ended up being pretty decent to legendary winters. 

Weather patterns don't often lock in for 3 months in a row in winter with no shake ups at all. Hopefully we can get the Pacific a bit more favorable as models are suggesting. 

[jaxjagman]

We hit 75 today,missed the record of 76 in 2016.Bah humbug !!

[Carvers Gap]

18z GFS to a lean towards the 12z CMC with the cold front on Jan 3rd.  Temps are 10-15 degrees below normal.  Let's see what it does with the AH this run.  Looks displaced already.  Pac Ridge has connected to the NAO....stage would seem to be set or a fairly southward displacement for cold air on this run.

[jaxjagman]

I remember the big snow when we first moved here was on Christmas day in Lawrenceburg we got around 10" and another storm dumped about 2-4" after that a couple days later,i was so excited to see snow  after living in Jacksonville,Fl where we rarely seen  snow ever then after that the dreaded snow dome came upon us

[Carvers Gap]

18z GFS does indeed begin to severely erode the AH immediately after 240.  Going to be some crazy cold air coming into the Lower 48 this run it would seem.

[Carvers Gap]

Will just use this post(update as the run progresses) to cut down on tons of posts for the rest of the 18z run:

-Hudson Bay high will drive this pattern for the rest of the way along with what would seem a very -AO.

-By 288 the big red blob over the Pac is adios'd

-The Hudson Bay high will force the storm track well south if real.  This would be an Atlantic dominated pattern if real.  Check that...AO dominated pattern and a HB high dominated pattern.  

-Europe has turned sharply colder by 288 which tele connects well to cold temps over the EC.

-1068 high coming down out of Canada around 300.  Super smiler to both the Euro and CMC which had monster highs coming down.

-Fairly massive Arctic outbreak being modeled after 300.  

-This is 2020 February 2.0 light...yikes

-Pretty epic run as at one point roughly 1/3 of the US (mid and upper Plains, Rockies) are below zero.

[tnweathernut]

Good discussion, guys.  Also, Merry Christmas…..We are going to need to need to see the displacement of the AH modeled under hour 180 to give me confidence in it happening.  It definitely makes sense to see it, but it could be rushed.  Hope the models are onto something and not just on something.  

[Carvers Gap]

@tnweathernut, looks like the first significant disruption of the AH begins around Dec 30/31 if modeling is indeed correct - between 120-130h.  Looks like a couple of storms crash into it.  Almost immediately after that, the area of hp loses its uniformity and lifts out over the next few days.  And you are on the money about whether this is correct or not...just tough to know.  I think this scenario very possible, but not ready to take the step and say it is likely.  18z GFS again with another flip of the pattern.  Agree also it could be rushing, but other modeling seems to be there with it.  What is crazy on this run is that NA gets so cold that the AN heights at 500 are still cold at the surface and the BN heights are even colder at the surface. What looks warm is just "less cold" air getting moved around.  Not sure I have seen that on a map in a long time.  At the end of the run, there is this big ridge in the central US....generally below normal at the surface with another shot of cold incoming.  

[Carvers Gap]

This may just be a case of climatology taking over(January is our coldest month).  We don't need as many things to be exactly right in order to get cold.  We'll see.  See all of those AN heights at 500 and so much cold at the surface is counterintuitive.  So, wary I am.

[Mr. Kevin]

Hopefully we aren't chasing unicorns again this winter lol. I believe any shift in the Pacific would help us long term and let's hope and pray it's not a temporary change because even in great patterns, it's tough, but in even tougher patterns, its almost impossible unless a incredibly timed setup ensues. I think we all know this but wanted to reiterate it.

[Carvers Gap]

18z GEFS has turned sharply colder in the LR.  Fairly unusual to see an ensemble which is -10F below normal at this range, especially in such a widespread fashion.  Keep in mind those departures are during the coldest part of the year.   Time will tell if these trends are indeed real.  I would suspect that moderates during ensuing runs as extremes rarely verify.  Seasonal will work along with( and this is important) an active STJ.  That might be one of the coldest runs I have seen from the GEFS in regards to the entire continent nearly being BN for temps.  @Holston_River_Rambler, can you GIF that just for posterity?  Again, unlikely that verifies to that extreme, but would be interesting just to keep as a reference.  Specifically, the daily temp anomalies for North America.....

 

[Carvers Gap]

For those who enjoy reading Webber(I am included).  Thanks to the MA forum for this share:

 

[Holston_River_Rambler]

@Carvers Gap

 

 

 

 

 

[Carvers Gap]

21 minutes ago, Holston_River_Rambler said:

@Carvers Gap

 

 

 

 

 

Thanks a ton!!!!

[Mr. Kevin]

Take a look at JB'S  Saturday summary. Pretty good today imo. Wxbell.com 

[Mr. Kevin]

10 minutes ago, Mr. Kevin said:

Take a look at JB'S  Saturday summary. Pretty good today imo. Wxbell.com 

Sorry guys. Weatherbell.com

[John1122]

Looking back at 2015, it was a Nino acting more like a Nina out west. Bone dry in So Cal, wet and cold in the Pac NW. The Pacific was driving the pattern regardless of ENSO. 

The pattern change started showing up on models around Dec 30th or so and finally arrived by mid-month. The Pac became more favorable and we had a nice 2 weeks of winter, a relaxation and then more winter in February.

Saw another year I'm going to look more into. Dec 1965 was also warm I believe, before something changed and Jan 1966 was major winter here. 

[John1122]

After looking, December of 65 wasn't as warm as I thought but mostly because the last few days of November into early December were frigid. The lowest temps for Dec were the first two days of the month. It went very warm with a few cool days into the end of the month. January came in super warm. It was 60s and 50s for the high and low New Years and the next day. Similar to today's temps. 

By January 5th the PNA went from negative to positive and the NAO/AO went negative and the bottom fell out temp wise and snow piled up. 15-20 inches in the last two weeks of January 1966. 

That was in a strong Nino year, which is normally not good for winter here but blocking up top overwhelms the ENSO state some years, for good or ill and winter doesn't behave like it would in an average year with that ENSO. This year the Aleutian block is so far west compared to normal Nina, it's overwhelming the pattern and not allowing normal Nina behavior. 

[Daniel Boone]

'60's had quite a bit of -PDO -NAO dominate Winters. Interesting to see what you come up with regarding '66 John.

[Daniel Boone]

Answered it just as I posted John, lol.

   Yeah, that confounded AH is definitely our Thorn. 

[Mr. Kevin]

26 minutes ago, John1122 said:

Looking back at 2015, it was a Nino acting more like a Nina out west. Bone dry in So Cal, wet and cold in the Pac NW. The Pacific was driving the pattern regardless of ENSO. 

The pattern change started showing up on models around Dec 30th or so and finally arrived by mid-month. The Pac became more favorable and we had a nice 2 weeks of winter, a relaxation and then more winter in February.

Saw another year I'm going to look more into. Dec 1965 was also warm I believe, before something changed and Jan 1966 was major winter here. 

Strongest niño on record I believe 15-16. It shut down DC with over 30inches mid January 

[Carvers Gap]

0z GFS commentary:

-Cold from for Jan 3 is 10-15F below normal.  

-Temps go below freezing on the 3rd.  Many places north I40 are not depicted to get back above freezing until the 5h.

-Would appear the GFS is again feeding back with a split trough where the western portion gets cut-off.  Could happen, but not sure

-Temps over the East are BN to much BN through he 6th.

-Impressive cold shot.  Take a look at the mslp maps vs 500.  You can see the cold underneath those ridges at 500 while looking at those surface maps.  Crazy.

-EPO ridge(albeit displace westerly a bit) goes into the Arctic.  Bout it. Cold looking run from the 3rd onward to the 8th, brief interlude of warm, and appears another cold shot inbound after a cutter.  

-Possible feedback error with the slp that drifts off the coast of California after 340.

[Carvers Gap]

18z CMC looks equally cold through Jan4th...and I am going to bed!  LOL.

[jaxjagman]

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE NASHVILLE TN
551 AM CST TUE JAN 4 2022

...CLIMATE SUMMARY FOR DECEMBER, 2021...

DECEMBER, 2021 WILL BE REMEMBERED AS ONE OF THE WARMEST DECEMBERS
ON RECORD, AND ALSO FOR MULTIPLE OUTBREAKS OF SEVERE WEATHER AND
TORNADOES ACROSS MIDDLE TENNESSEE.

THERE WERE 5 TORNADOES REPORTED DURING THE EARLY MORNING OF 
DECEMBER 6. A MUCH MORE DESTRUCTIVE OUTBREAK OCCURRED ON THE NIGHT
OF DECEMBER 10-11, WHEN 17 TORNADOES TOUCHED DOWN, INCLUDING AN 
EF-3 AND TWO EF-2'S. THIS IS ONE OF THE LARGEST TORNADO OUTBREAKS 
EVER TO HAVE OCCURRED IN MIDDLE TENNESSEE.

THIS WAS ALSO THE SECOND-WARMEST DECEMBER ON RECORD. IN NASHVILLE,
THE AVERAGE TEMPERATURE WAS 53.4 DEGREES, WHICH WAS 10.7 DEGREES
ABOVE NORMAL. THE AVERAGE HIGH TEMPERATURE WAS 64.2 DEGREES AND
THE AVERAGE LOW TEMPERATURE WAS 42.5 DEGREES. THE HIGHEST
TEMPERATURE WAS 76 DEGREES ON CHRISTMAS DAY. THE LOWEST
TEMPERATURE WAS 26 DEGREES ON THE 23RD. THERE WERE 9 DAYS ON WHICH
THE TEMPERATURE DROPPED TO 32 DEGREES OR BELOW.

RAINFALL ADDED UP TO 3.63 INCHES. THIS WAS 0.80 INCHES BELOW
NORMAL. THE GREATEST 24-HOUR RAINFALL WAS 1.34 INCHES ON THE 5TH
AND 6TH. THERE WERE 11 DAYS WITH MEASURABLE RAINFALL. THERE WAS NO
SNOW. THERE WERE 6 DAYS WITH THUNDERSTORMS. THE FASTEST WIND GUST
WAS 78 MPH ON THE 11TH.

NASHVILLE FINISHED 2021 WITH AN AVERAGE TEMPERATURE OF 61.8 
DEGREES. THIS WAS 1 DEGREE ABOVE NORMAL. RAINFALL FOR 2021 WAS 
59.32 INCHES, WHICH WAS 8.81 INCHES ABOVE NORMAL.

IN CLARKSVILLE, THE AVERAGE TEMPERATURE WAS 52.3 DEGREES, WHICH 
WAS 12.4 DEGREES ABOVE NORMAL. THE AVERAGE HIGH TEMPERATURE WAS 
63.6 DEGREES AND THE AVERAGE LOW TEMPERATURE WAS 40.9 DEGREES. 
THE HIGHEST TEMPERATURE WAS 76 DEGREES ON THE 11TH, AND AGAIN ON  
CHRISTMAS DAY. THE LOWEST TEMPERATURE WAS 24 DEGREES ON THE 20TH.
THERE WERE 11 DAYS ON WHICH THE TEMPERATURE DROPPED TO 32 DEGREES
OR BELOW.

RAINFALL ADDED UP TO 3.39 INCHES. THIS WAS 0.97 INCHES BELOW 
NORMAL. THE GREATEST 24-HOUR RAINFALL WAS 0.91 INCHES ON THE 5TH 
AND 6TH. THERE WERE 10 DAYS WITH MEASURABLE RAINFALL. THERE WERE 4
DAYS WITH THUNDERSTORMS. THE FASTEST WIND GUST WAS 61 MPH ON THE 
11TH. A 53-MPH GUST WAS ALSO RECORDED ON THE 6TH.

IN CROSSVILLE, THE AVERAGE TEMPERATURE WAS 48.8 DEGREES, WHICH 
WAS 10.0 DEGREES ABOVE NORMAL. THE AVERAGE HIGH TEMPERATURE WAS 
58.5 DEGREES AND THE AVERAGE LOW TEMPERATURE WAS 39.1 DEGREES. 
THE HIGHEST TEMPERATURE WAS 70 DEGREES ON THE 3RD. THE LOWEST 
TEMPERATURE WAS 22 DEGREES ON THE 23RD. THERE WERE 12 DAYS ON 
WHICH THE TEMPERATURE DROPPED TO 32 DEGREES OR BELOW.

RAINFALL ADDED UP TO 5.01 INCHES. THIS WAS 0.33 INCHES BELOW 
NORMAL. THE GREATEST 24-HOUR RAINFALL WAS 1.44 INCHES ON THE 29TH.
THERE WERE 10 DAYS WITH MEASURABLE RAINFALL. THERE WERE 3 DAYS 
WITH THUNDERSTORMS. THE FASTEST WIND GUST WAS 47 MPH ON THE 11TH.

CROSSVILLE FINISHED 2021 WITH AN AVERAGE TEMPERATURE OF 56.2 
DEGREES. THIS WAS 0.9 DEGREES ABOVE NORMAL. RAINFALL FOR 2021 WAS 
56.21 INCHES, WHICH WAS 1.32 INCHES BELOW NORMAL.

THE OUTLOOK FOR JANUARY FROM THE CLIMATE PREDICTION CENTER FOR
MIDDLE TENNESSEE CALLS FOR NEAR NORMAL TEMPERATURES AND ABOVE
NORMAL PRECIPITATION.