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Winter Speculation 17/18 -December Thread

AMZ8990

By AMZ8990,
in Tennessee Valley

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jaxjagman

jaxjagman

Posted
Posted

Mega ice storm Birmingham

  

THU 00Z 28-DEC   1.0    -1.0    1040      35      94    0.00     575     544    
THU 06Z 28-DEC  -1.2     0.8    1040      38      96    0.00     576     545    
THU 12Z 28-DEC  -3.2    -0.9    1040      89      99    0.07     576     544    
THU 18Z 28-DEC  -1.0    -1.1    1039      90      99    0.12     577     546    
FRI 00Z 29-DEC  -0.6    -1.5    1038      93      98    0.08     577     548    
FRI 12Z 29-DEC  -2.9     1.1    1037      93     100    0.35     577     549    
SAT 00Z 30-DEC  -2.3     2.0    1035      94      91    0.24     575     548    
SAT 12Z 30-DEC  -3.1     2.3    1032      93      90    0.08     573     548    
SUN 00Z 31-DEC   0.9     2.8    1028      99      97    0.04     571     549    
SUN 12Z 31-DEC   0.5     1.9    1025      97      95    0.01     569     549    
MON 00Z 01-JAN   2.0     0.8    1024      99      83    0.01     567     548    
MON 12Z 01-JAN  -5.0     0.1    1026      93      28    0.00     567     547    
TUE 00Z 02-JAN  -1.6    -0.3    1028      95      32    0.00     569     547    
TUE 12Z 02-JAN  -5.2     1.9    1029      91      26    0.00     571     549    
WED 00Z 03-JAN   0.5     1.7    1027      96      52    0.00     570     549    
WED 12Z 03-JAN  -1.2     0.9    1028      95      80    0.00     567     545    
THU 00Z 04-JAN   2.0     2.8    1026      96      86    0.00     566     545
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Carvers Gap

Carvers Gap

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You can see where energy is sliding under the base of that EPO ridge.  This makes much more sense under a tall EPO ridge than backing  a trough under there and leaving it.  1 and 2 are those pieces of energy.  3 is the question mark.  Will there be a point of confluence where one of those lows phases w energy from the northern branch.  The pattern is what needs to be identified...and I am hoping we get split flow w 1050+ highs.  Right now this is a Deep South snow pattern.  MS and AL, even Louisiana, are in the game.  If the cold comes in pulses like the 0z implied...then there might be enough space between cold shots for the energy to come north.  That is what is called a loaded pattern.  Who knows if it verifies....but nice to see it being shown this way.  Even northern energy could spawn a storm.   

IMG_0664.PNG

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ShawnEastTN

ShawnEastTN

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7 hours ago, Carvers Gap said:

You can see where energy is sliding under the base of that EPO ridge.  This makes much more sense under a tall EPO ridge than backing  a trough under there and leaving it.  1 and 2 are those pieces of energy.  3 is the question mark.  Will there be a point of confluence where one of those lows phases w energy from the northern branch.  The pattern is what needs to be identified...and I am hoping we get split flow w 1050+ highs.  Right now this is a Deep South snow pattern.  MS and AL, even Louisiana, are in the game.  If the cold comes in pulses like the 0z implied...then there might be enough space between cold shots for the energy to come north.  That is what is called a loaded pattern.  Who knows if it verifies....but nice to see it being shown this way.  Even northern energy could spawn a storm.   

IMG_0664.PNG

Its been so long since I have seen good southern sliders, back in the 90s probably is the last time I remember.  The pattern you are showing there that is the classic set up for sliders correct?

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tnweathernut

tnweathernut

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Generally optimistic this morning for something down the road in the not too distant future.  I think any rain changing to snow scenario for Christmas is a long shot for most in our region, but something to watch I guess. 

It's the period just after that holds most interest, IMO.  Good graphic and post, Carvers.  It lines up with my thinking of a cold press into the northern plains (thank you -EPO) feeding multiple (larger than normal) highs into the area while the southern jet supplies a couple (at least) of impulses.  We'd still have to rely on timing and worry about the depth of cold and there would be winners and losers, but overall it's probably the best look we have seen so far in this young winter season. 

Just because we write about what we see doesn't mean it has to play out this way.  The last 4 runs of the EPS have trended toward less and less SE ridging out in time.  Most modeling is on board with the same general look (ridge west, trough east) so that is also encouraging.  Should be fun to follow......

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Carvers Gap

Carvers Gap

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I agree w what others have said.  Nice pattern potentially upcoming.  Don't mistake a lack of posts for a change to a bad pattern.  The pattern still looks good if not just a tad slower.  Pay me now or pay me later type pattern.  Even the Weeklies , which were terrible last TR, showed cold into week 4 this run.  Right now (knock on wood), the cold looks to be coming.  I am interested in how strong the cold will be.  The past two runs of GFS/GEFS tended to back off the duration of cold, but I think it is a known bias of breaking down the pattern too quickly.  The EPS was cold and supported a pattern that would keep the East cold through the New Year.  Now...there are going to be breaks in these waves of cold.  I think the the precip will be embedded in these temporary breaks.  But with so much reinforcing cold....have to think we will see multiple events to track if we get split flow.  We have all seen patterns strike out.  We indeed live at a latitude where it does not want snow most times of the year.   Our base state is rain.  So, we always have things working against even when things look good.  But we also live in a place thanks to our relative position to the Atlantic and GOM where bi storms can and do happen.  

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Carvers Gap

Carvers Gap

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Posted
2 hours ago, ShawnEastTN said:

Its been so long since I have seen good southern sliders, back in the 90s probably is the last time I remember.  The pattern you are showing there that is the classic set up for sliders correct?

Flash covered it pretty much...I think w big highs in place, it will be tough for anything to cut unless there is enough separation between repetitive cold shots.  It could happen...warm up and rain as the old saying goes.  But if we have 1050+ highs that verify in the Plains, that is rarified air.  I think systems that enter the West under the EPO ridge will be forced well South.  I have said it several times...the southwest sections of our forum area are in the game.  The one scenario that keeps popping up is snow or ice in northern MS/AL and southwest TN.  I definitely am worried about ice if the trend is to shallow out the trough over NA.  We want to see the bottom of that trough to be centered west of this past cold outbreak and broad.

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tnweathernut

tnweathernut

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Posted
1 minute ago, John1122 said:

The GFS is pretty much a useless mess. It's probably going to get cold around Christmas. Beyond that it's either going to be frigid or there's going to be no cold in the lower 48 at all according to which run you believe in the last 12 hours.

Was just noticing that.  I am guessing the fact the 12z GFS blew up the Great Lakes low around 102 (986mb vs 1002 prior runs) led it to be wonky later in the run... butterfly effect fun..

I'd definitely toss this run long range and follow the ensembles.  They, at the very least, should be less useless.  lol

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nrgjeff

nrgjeff

Posted
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GFS Ensembles did not budge 12Z Tue. Still cold. Here is my thinking combining ensembles and weeklies.

Looks like two weeks of cold, with a milder interlude or maybe just less strong cold within the two weeks. Weather system (maybe rain) is possible after Christmas. Perhaps another cold shot for New Year's.

Early next week looks really cold a morning or two. Late next week system is possible, well actually likely somewhere, but many questions remain here. Models are juggling pieces of energy north and south, both track and relative timing. Pattern recognition puts another cold shot behind the said system. Ensembles do keep the 11-15 day cold. Weeklies have that third week (of New Year's) colder than normal. So I think two weeks of cold is reasonable.

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tnweathernut

tnweathernut

Posted
Posted

I'm not enamored with looking at super long range stuff, but you'd think occasionally a 7 day map could potentially have merit.  If we get the following look from the 12z Euro OP today, there will likely be fun and games 2-3 days later.

1. -EPO

2. -AO

3. -NAO

4. Huge cold vortex over Hudson Bay

5. Shortwave in the flow in the northwest US diving SE.

6. As this dives SE it bends the 500 level out of the WSW.

7. Overrunning would quickly develop

8. Confluence would send the overrunning quickly east into the cold dome of air at the surface.

In short, it's a GREAT look in the mid-south for potential winter weather a couple of days later.  Is it right?  Who knows??

Euro OP 500 168hr 12192017 valid 7am 12262017.png

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John1122

John1122

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Posted

The Control had 12-26 inches from the border Counties along the KY and Va lines, around 8-12 on the southern tips of the counties increasing to 16+ on the actual state lines. Not sure how much was ice. 2-4 inches of snow south of that. Appeared to have the valley warm nose big time in the east with no snow cover shown in the southern valley of East Tennessee. Not sure if it was ice or rain in the southern valley. I can only see snowfall maps from it and not p-type and not sure how much ice is counted as snow on there.

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Chattownsnow

Chattownsnow

Posted
Posted
13 minutes ago, John1122 said:

The Control had 12-26 inches from the border Counties along the KY and Va lines, around 8-12 on the southern tips of the counties increasing to 16+ on the actual state lines. Not sure how much was ice. 2-4 inches of snow south of that. Appeared to have the valley warm nose big time in the east with no snow cover shown in the southern valley of East Tennessee. Not sure if it was ice or rain in the southern valley. I can only see snowfall maps from it and not p-type and not sure how much ice is counted as snow on there.

looking at the control run on weatherbell (it only goes out to 240hr). it looks as though pretty much Murfreesboro is the extent of ice to the south. There is a beautiful 1047-1043 banana H over the top driving down the freezing line slowly as the moisture works across however at 240. NC/SC look poised for a massive ice storm however south of where the snow extent is shown on the clown map. looks like the southern valley is rain though verbatim. 

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Carvers Gap

Carvers Gap

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If there is a 1045ish high to the north...the ice line will be further south than modeled.  The Euro was toying w the idea a few days back...now the models have it again.   Is it right?  No idea.  Give me precip.  Give me big, cold highs.  And let's see how it shakes out.  The snowfall maps are not as important as the pattern.  There appears to be opportunity for coastal areas to maybe see a wave develop into a Miller A around Christmas Day....then split flow arrives.  The models will be a mess.  If we get split flow and cold...hang on.

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