December and January Pattern Discussion

[Carvers Gap]

Normally, I think it is a good idea to just do one month per pattern discussion.  Since we are half-way through December, I say let's put Dec/Jan into one discussion in terms of sensible wx patterns.  For upcoming and short range events, such as this weekend, use Stovepipe's.  This thread will be for discussing the upcoming early to mid-winter pattern.  The pattern looks blocky upcoming, but the NAO says nah.  The southeast ridge could be to our benefit depending on where it sets up shop. 

[John1122]

The SE ridge can be excellent from just west of Nashville and points westward. NW Miss to Clarksville often make out pretty well with it in place. 

 

It seems tough to ever get it to benefit N. Ala and East Tennessee very much though.

[1234snow]

0z GFS really digs the trough south over the Desert Southwest which pumps up our friend the SE Ridge.

[Carvers Gap]

0z GFS says maybe a line of severe storms next weekend in west Tennessee, northwest Arkansas, and southwest Kentucky before the pattern breaks for cold again.  Check out those -30s sliding across Canada.  Won't make it here, but still...cold North American temp wise.

[Carvers Gap]

@ 192 hr on the 0z Euro....that is cold HP sitting over the Hudson Bay.  I would think normally that is a spot you want cold air to be if you want winter wx west of the Apps.  Yet, the SE ridge holds its ground.  Though, it would seem that if one rolled the pattern forward, the period around or just after Christmas is looking more promising.  Climo would support this as well.  Edit:  Strongly positive NAO depicted at day 10 FWIW. 

[John1122]

I may be get a shock, but I don't think we'll see a truly notable winter event East of Western Tennessee the rest of the month. It may get cold and dry, we may get a snow shower or two here or there, but until we get a better set of teleconnections, we'll struggle from Nashville to Bham and points East.  Right now the only slight positive on that front is the potentially neutral/weakly positive PNA that may show up in the LR. 

[Carvers Gap]

I may be get a shock, but I don't think we'll see a truly notable winter event East of Western Tennessee the rest of the month. It may get cold and dry, we may get a snow shower or two here or there, but until we get a better set of teleconnections, we'll struggle from Nashville to Bham and points East.  Right now the only slight positive on that front is the potentially neutral/weakly positive PNA that may show up in the LR. 

 

...Another wet weekend(not this one) on tap.  MRX thinks maybe so.  In all seriousness, we needed the rain.  But when they use the word, "foreboding," usually means flooding in this context - especially after the rains from this weekend.

 

.LONG TERM (SUNDAY NIGHT TROUGH FRIDAY)...

A GENERALLY QUIET AND DRY PERIOD UNTIL WE GET TO THE VERY END.

STILL EXPECTING A WARMING TREND FOR NEXT WEEK...WENT MORE TOWARD

THE WARMER ECMWF TEMPERATURES THAN THE GFS. WEATHER SYSTEM FOR THE

END OF THE WEEK LOOKS POTENTIALLY FOREBODING. BOTH GFS AND ECMWF

INDICATE A SLOW MOVING FRONTAL BOUNDARY OVER THE TENNESSEE AND OHIO

VALLEYS FROM FRIDAY THROUGH SUNDAY WITH A NOTABLY MOIST GULF FLOW

FEEDING THE WARM SECTOR. PRECIPITATION MAY BE FAIRLY EFFICIENT IN

THIS SET UP...AND RAINS OF A DAY OR TWO DURATION SOMEWHERE IN

MIDDLE OR EAST TENNESSEE MAY ACCUMULATE ON THE ORDER OF SEVERAL

INCHES. BEING OUT IN THE DAY 7 TIME FRAME AND BEYOND...THE MODELS

WILL LIKELY STRUGGLE TO PIN IT DOWN BEFORE EARLY NEXT WEEK. WHAT

MATERIALIZES WILL DEPEND ON THE STRENGTH OF THE WESTERN TROUGH AND

THE SW FETCH OVER THE EASTERN U.S. THEN...HOW MUCH OF A TROPICAL

TAP WILL ALL OF THIS MAY MUSTER? BUT THE SITUATION BEARS MONITORING

PRIMARILY FOR PLACEMENT OF HEAVY PRECIP AXIS.

 

[Carvers Gap]

6z GFS showing quite an event for west and middle(edit) Tennessee late next week, especially for December.  Total precip map below for the run.

[Carvers Gap]

December 23rd has an interesting look w/ cold HP to our north.  Might be a good look for Memphis.  Could just be a cold rain.  Just depends on how far that boundary dives south.

 

edit:  Should add that this is something to watch.  Not a likely event.  Where that LP goes will be key of course. 

[tnweathernut]

It appears the models keep pushing back the mother lode of cold, although they do keep showing it coming. I don't think I have EVER seen a 1064 high in the US. Pretty crazy......

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[franklin NCwx]

Well at least in did not dig the trough into the west.

[1234snow]

12z GFS suppresses/ digs our shortwave more to the south than any of the more recent runs of the model. The 0c almost makes it into the region before the flow rises from the Gulf:

By the end of the run the axis of heavy rain has shifted to the east by a good hundreds of miles:

This is a good trend in the right direction at least for one run. Interested to see what CMC/Euro shows.

[calculus1]

That last GFS image appears to show quite the C** (Is that a dirty word in this forum?!) signature for east of the Appalachians.  Could get interesting over there.  You guys need that cold air to dig down a little deeper in the heartland, while we (on the other side) would like to see that NE high pressure grow a little stronger and bleed more down through the mid-Atlantic regions.

[tnweathernut]

Not a bad look just on the edge of truncation. Interesting to see a 1020s high where we have been seeing 1030s and 1040s. Lots of confluence there and if the high is closer to what we have been seeing so far this year, some in the mid south could have an opportunity coming.

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[Carvers Gap]

That last GFS image appears to show quite the C** (Is that a dirty word in this forum?!) signature for east of the Appalachians.  Could get interesting over there.  You guys need that cold air to dig down a little deeper in the heartland, while we (on the other side) would like to see that NE high pressure grow a little stronger and bleed more down through the mid-Atlantic regions.

Has a familiar feel to the last winter storm. Boundary gets strung out west to east. HP parked to our north. Does indeed have an icy look for my neighbors to the east if the model trends. We'll see what the Canadian and Euro say. I am with TNWxNut and 1234...plenty to look for depending where all of the pieces wind up. Better than last year in terms of weather watching.

[Clarksville Snowman]

I think my area is gonna be a close call again next weekend if the model trends continue. Would like to see the cold air come just a liitle further south than the last storm as we got ice. If we had gotten much more ice at all it would have been bad, if temp had been just a degree lower it would have made a difference also, we were close. Ready for some winter weather for sure, here's hoping the models trend our way in the tennessee valley region.

[1234snow]

That last GFS image appears to show quite the C** (Is that a dirty word in this forum?!) signature for east of the Appalachians.  Could get interesting over there.  You guys need that cold air to dig down a little deeper in the heartland, while we (on the other side) would like to see that NE high pressure grow a little stronger and bleed more down through the mid-Atlantic regions.

 

You need to wash your mouth out with soap! Just joking.

 

12z Canadian has a similar look but it seems the trough is much broader than the GFS. I would think that we would need a tighter packed shortwave to help pull down cold air.

 

[calculus1]

You need to wash your mouth out with soap! Just joking.

 

 

I had to poke just a little fun at my TN Valley friends! 

 

I'm going to miss all you guys posting in the normal spots.

 

Anyway, GFS shows potential, perhaps the Canadian, now on to the Euro and five+ more days of model watching until this next potential event arrives.  Here's hoping we can cook up something that will plaster all the TN Valley and the SE locales. 

[tnweathernut]

The Euro and GFS really couldn't look much different in the long range. At least they agree on a +NAO, right?? lol.

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[John1122]

I'd love to see some blocking show up to allow that 1064 monster (I'll be shocked if it's more than 1050) to road grade the SE ridge about 500-800 miles S/SE. 

[tnweathernut]

Cold and dry........I will pass John!

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[John1122]

I just hate the SE ridge. With the active southern stream, we'd eventually get a storm to roll across.

Cold and dry........I will pass John!


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[jaxjagman]

On todays 12z 500 mb anomalies the euro breaks away part of the PV.The question is where it goes?We might get a hint on the Euro esm. 12z.Something to keep a eye on.It can go either E or in NA.

[tnweathernut]

On todays 12z 500 mb anomalies the euro breaks away part of the PV.The question is where it goes?We might get a hint on the Euro esm. 12z.Something to keep a eye on.It can go either E or in NA.

Well we know what the GFS does with it......lol.

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[Clarksville Snowman]

On todays 12z 500 mb anomalies the euro breaks away part of the PV.The question is where it goes?We might get a hint on the Euro esm. 12z.Something to keep a eye on.It can go either E or in NA.

Why not south!! LOL!

[jaxjagman]

Well we know what the GFS does with it......lol.

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I know what u mean

[Carvers Gap]

The Euro and GFS really couldn't look much different in the long range. At least they agree on a +NAO, right?? lol.

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The GFS seems to be slightly more amplified w/ its elongated trough centered in the middle of the country.  The Euro is more zonal by the end of its run.  That said, the GFS doesn't really look good until about day 13.  I think a change is on its way.  As usual, the GFS is moving to quickly w/ the change.  I would say we have about ten more days, and then things begin to show up which are truly chances.  Anyway, it will be a blast to be able to follow the storm in the TN Valley thread.  I would guess, we will get a ton of new folks as we move into the heart of winter and sever weather season.

[jaxjagman]

Key is what will happen is Japan in a day or two.Because what happens in this area  to make a long story short effects North America when it recurves 6-10 days later.-PNA..+NAO would suggest a mean trough pops up.But if we have no help from the PV,forget it unless you like rain.Said in a simple way

[Carvers Gap]

The 18z GFS looks remarkably like the 12z through 216.  Really no mechanism to get the really cold arctic air into the SE.  We almost need a storm to spin up and drive down some backside cold - and maybe set the stage for the following SW.  Then the storm can slide up and pop the -NAO.  I hate to say it, but this pattern looks all but locked in for the next two weeks.  There are some signs that the pattern reshuffles just after Christmas.  But hey, we don't get a ton of snow in the TN Valley in December...So, no big deal.  Our "money" weeks are January to mid-March.  What would be interesting is if that cold air drove into the SE during what would be climatologically our coldest weeks of the season.  Pipe busting weather that would be.   

[franklin NCwx]

The 18z GFS looks remarkably like the 12z through 216. Really no mechanism to get the really cold arctic air into the SE. We almost need a storm to spin up and drive down some backside cold - and maybe set the stage for the following SW. Then the storm can slide up and pop the NAO-. I hate to say it, but this pattern looks all but locked in for the next two weeks. There are some signs that the pattern reshuffles just after Christmas. But hey, we don't get a ton of snow in the TN Valley in December...So, no big deal. Our "money" weeks are January to mid-March. What would be interesting is if that cold air drove into the SE during what would be climatologically our coldest weeks of the season. Pipe busting weather that would be.

it would be nice to see a cutter really bomb.