December/January 2019/20 Winter Speculation Thread

[Carvers Gap]

4 minutes ago, Holston_River_Rambler said:

Here's the 12z Euro strat:

 

It is interesting.  I think the American suite brings the PV back together.  So many unknown variables right now - more than usual!

[weathertree4u]

8 minutes ago, Holston_River_Rambler said:

I think the key for the Ensembles is how they deal with the ridging that sandwiches the SPV. Because everything is so coupled, when you have the -EPO and NAO ridging, it percolates up to affect the strat. You can see it here as the yellows and oranges that correlate to the NAO and EPO regins in the arctic:

cross polar flow still there at the end, even more amplified as carvers said

Interesting

[Holston_River_Rambler]

18z NAM coming in north and more precip with the Wed morning system. Dry air though between 850 and 650mb. Definitely the furthest north it has been, we'll see if it holds together. 12z UK and Euro dissolve it over TN

[Holston_River_Rambler]

It's just the NAM and one run, but it's the best look for board wide possibility for many, all winter:

N stream kind of squishes the vort, but plenty of time for changes for betrer or worse:

[Carvers Gap]

The 18z GFS at 252....-NAO much?

[Carvers Gap]

What is interesting is that as the features on the map have retrograded a bit(trough taking peak in the West), AN heights have also backed into Greenland.  Something to watch.   And if you watch the NA 500 anomaly map evolve at 192, notice how the trough doesn't get stuck like it does on the Euro.  Then, watch the differences.  

https://www.tropicaltidbits.com/analysis/models/?model=gfs&region=namer&pkg=z500a&runtime=2020012618&fh=264

[Carvers Gap]

AT 354, all of NA is BN.  I suspect the GFS in phases 2 or 3 of the MJO with that look.  I would be hard pressed to find a better run this season IMHO.  Yes, it is the GFS so everyone knows the rules.  But one can still admire that run.

[Carvers Gap]

Accumulation amounts in the eastern half of Tennessee generally range from 4-14" snow with the greater amounts over the Plateau.  Much of the eastern half of the forum area has 6" plus.

edit:  eastern half defined in this case as mid-state to the Smokies

[weathertree4u]

13 minutes ago, Carvers Gap said:

Accumulation amounts in the eastern half of Tennessee generally range from 4-14" snow with the greater amounts over the Plateau.  Much of the eastern half of the forum area has 6" plus.

edit:  eastern half defined in this case as mid-state to the Smokies

I think we are seeing some good trends!

[Carvers Gap]

Just now, weathertree4u said:

I think we are seeing some good trends!

I don't like the western trough deal on ensembles late in each run, but that is the consequence of no Atlantic block.  However, the way the gradient stretches out(on ensembles) would probably still mean the boundary would move to our south some.  Looks to me like mid-Texas to DC would be the boundary on ensembles.  Storms would run that boundary speaking of later in the run.  

The 18z GFS is probably an outlier run(to other models...similar to other GFS runs) due to how it keeps reinforcing the eastern trough.  All of that said, I am most interested to see if other subsequent runs of the GFS and other modeling begins to catch blocking over Greenland.  Probably the single, greatest feature that makes this an outlier is the block over Greenland.  I will also be interested in seeing the MJO forecasts during the next few days.  What we can hope for is that the 18z GFS is catching a trend as it sometimes does.  But we can enjoy it until 0z.   I say that, because the GFS has been flipping from blocking to no-blocking like flipping a light switch.  The 18z GFS does illustrate how a little help from the Atlantic could hold the eastern trough in place.  

[Carvers Gap]

Additionally, it may be that modeling is beginning to "feel" the disruption of the PV which will induce blocking.  Nothing is a given this winter....

[Carvers Gap]

18z GEFS is a slight improvement and obviously very cold after an operational like that.  The SER forms later and actual surface temps remain normal under the SER with such powerful temps to the NW.  Again, as mentioned above, that is a workable look even late in the run.

[Holston_River_Rambler]

Looks like the 18z Euro is kinda digging the NAM, except for its thermals:

The precip type maps haven't populated yet for weathermodels, but looks more like rain out to hour 66. 

[PowellVolz]

Looks like the 18z Euro is kinda digging the NAM, except for its thermals:

The precip type maps haven't populated yet for weathermodels, but looks more like rain out to hour 66. 

That looks like a nice path for orographic lift on those NW facing slopes


.

[jaxjagman]

11 hours ago, Holston_River_Rambler said:

Ok, specifically, tell me what is unrealistic about what I've posted? We can bring this back to pattern speculation by looking at the details and critiquing the specifics of what I posted.

I posted several maps that suggested the mid-week storm might over perform, but that the UKMET was on an island with how much precip it spit out as snow. 

I posted some maps that suggested the SPV was going to stretch out and possibly split. 

 

 Jax was saying that the East Asian jet would retract, using a GEFS map of the eastern US for support.  I see no evidence for that.

s

Looks fairly stout to me on the Euro and GFS in east Asia. 

But Jax is much better with things like the East Asia rule and I respect him, so I saw no reason to contradict what he said. Maybe he sees something I don't. 

 

Not sure i worded it right,It doesn't mean you can't get cold.I was talking about the jet extension in East Asia.This will cut off the active pattern we've been seeing because troughs will be more or less up north and we will possibly be dealing with some sort of SER.It's really a crappish look IMO

[John1122]

NAM coming in stronger but warmer for the midweek system. Won't be surprised if it shows all rain south of Kentucky this time. 

[John1122]

Yep. Through 57 hrs the frozen line is a good 80 miles north of the 18z frozen line.  Typical luck. 

[jaxjagman]

2 minutes ago, jaxjagman said:

Not sure i worded it right,It doesn't mean you can't get cold.I was talking about the jet extension in East Asia.This will cut off the active pattern we've been seeing because troughs will be more or less up north and we will possibly be dealing with some sort of SER.It's really a crappish look IMO

 

[John1122]

Looks like the frozen line dips into the Northern Plateau by 60. 18z Nash to Knox was seeing snow. This run Bowling Green to Tazewell is more the area. Fine details but this is a border line cold event. It arriving overnight into very early morning is one thing in the favor of the areas from your Plateau west. 

[John1122]

West Tennessee gets a nice backside thumping there. Looks like we night horseshoe with snow in western NC and West Tennessee but rain mostly for the rest of us. Hope the backside works it's way across the state but looks like it might lift NE instead. 

[John1122]

Nope, no luck for the rest of us. NW areas and Western NC are the winners that run. 

 

Really strange, TBH, 850s are 0 or less into Georgia, the 540 line is south of Birmingham and Atlanta but surface temps are in the 40s overnight and most of us rain. 

[PowellVolz]

Nope, no luck for the rest of us. NW areas and Western NC are the winners that run. 
 
Really strange, TBH, 850s are 0 or less into Georgia, the 540 line is south of Birmingham and Atlanta but surface temps are in the 40s overnight and most of us rain. 

That’s interesting. Should get some wet bulb and dynamic cooling to help but maybe it is

[jaxjagman]

40 minutes ago, John1122 said:

Nope, no luck for the rest of us. NW areas and Western NC are the winners that run. 

 

Really strange, TBH, 850s are 0 or less into Georgia, the 540 line is south of Birmingham and Atlanta but surface temps are in the 40s overnight and most of us rain. 

there iis a warm nose into the lower levels,you might be able to over come this with your elevation,for us you want to see this happen in the evening

[PowellVolz]

there iis a warm nose into the lower levels,yiou might be able to over come this with your elevation,for us you want to see this happen in the evening

925mb about 3k in elevation?


.

[jaxjagman]

Just now, PowellVolz said:

925mb about 3k in elevation?


.

Should be about 2500 ft

[jaxjagman]

I wouldnt trust the soundings like John mnetioned,they are way to warm with the 850mb,the problem is the 925MB,levels with a warm nose with winds S/SW

[John1122]

GFS is a little better, doesn't get it done for us but NW trend definitely on the precip shield. Still low level warm issues. Keep having these early spring type looks where even good tracks rain low and snow above 4000ft. 

[jaxjagman]

Least we have a chance for some snow,but you have to get up early before it goes back to liquid to see it by the NAM

[jaxjagman]

16 minutes ago, John1122 said:

GFS is a little better, doesn't get it done for us but NW trend definitely on the precip shield. Still low level warm issues. Keep having these early spring type looks where even good tracks rain low and snow above 4000ft. 

Definite have to look at the levels.You want this to fall at night or have some heavier QPF's which would cool the thermals down maybe

 

 

GFS 0.5 Degree FORECAST FOR: TYS    LAT=  35.82 LON=  -83.98 ELE=   981

                                            00Z JAN27   * - APPROXIMATED
                 2 M     850    1000    FZING    SFC     SFC    6 HR    SNCVR
                 TMP     TMP     850     HGT     WIND    PCP     QPF     LIQ 
                 (C)     (C)     THK    (FT)    (KTS)   TYPES   (IN)    (IN) 
MON 00Z 27-JAN   5.7     1.6     132    5833    23002                   0.01    
MON 06Z 27-JAN   5.1     1.5     132    5714    22005           0.01    0.01    
MON 12Z 27-JAN   5.2     1.0     132    5228    24005     RA    0.13    0.01    
MON 18Z 27-JAN   8.4    -0.2     133    4580    26006     RA    0.11    0.03    
TUE 00Z 28-JAN   5.8    -1.3     132    4021    31003           0.08    0.01    
TUE 06Z 28-JAN   3.3    -1.7     131    3005    35002           0.00    0.03    
TUE 12Z 28-JAN   2.3    -1.6     130    2290    02002           0.00    0.03    
TUE 18Z 28-JAN   6.9    -0.1     131    3750    32003           0.00    0.01    
WED 00Z 29-JAN   3.6    -0.4     131    3768    05003           0.00    0.01    
WED 06Z 29-JAN   2.5    -0.5     131    4117    05003           0.00    0.01    
WED 12Z 29-JAN   1.7    -1.0     131    4147    05002           0.00    0.01    
WED 18Z 29-JAN   8.3     0.5     132    5070    04004           0.00    0.01    
THU 00Z 30-JAN   6.3    -0.6     132    4059    00003     RA    0.03    0.01    
THU 06Z 30-JAN   4.9    -0.6     132    4243    01003     RA    0.04    0.01    
THU 12Z 30-JAN   4.4    -2.1     131    3542    36003           0.02    0.01    
THU 18Z 30-JAN   7.7    -1.8     131    3472    35002           0.00    0.01    
FRI 00Z 31-JAN   6.5    -1.9     132    4082    23000           0.00    0.01    
FRI 06Z 31-JAN   4.3    -1.4     132    5051    18001           0.00    0.01    
FRI 12Z 31-JAN   4.5    -1.6     131    3868    12002     RA    0.00    0.01    
FRI 18Z 31-JAN   7.3    -1.8     132    3869    17002     RA    0.02    0.01    
SAT 00Z 01-FEB   5.1    -1.4     131    3971    24002           0.05    0.03    
SAT 06Z 01-FEB   4.6     0.1     132    4819    09001     RA    0.02    0.03    
SAT 12Z 01-FEB   4.7    -0.5     132    4377    18001     RA    0.06    0.03  

[jaxjagman]

Not sure if  it's going to do the trick,we was fooled earlier.Control don't show a split today