December 2020 Medium/Long Term Pattern Discussion.

[Carvers Gap]

13 minutes ago, jaxjagman said:

GFS 0.5 Degree FORECAST FOR: CHA    LAT=  35.03 LON=  -85.20 ELE=   689

                                            12Z DEC18   * - 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) 
FRI 12Z 18-DEC  -2.9    -1.9     129       0    02003                   0.00    
FRI 18Z 18-DEC   6.6     1.0     131   10250    02004           0.00    0.00    
SAT 00Z 19-DEC   0.9     3.4     131   10309    04003           0.00    0.00    
SAT 06Z 19-DEC  -0.6     3.8     131   10176    10001           0.00    0.00    
SAT 12Z 19-DEC  -1.2     2.7     131    9386    16002           0.00    0.00    
SAT 18Z 19-DEC   8.5     3.3     132    8834    17007           0.00    0.00    
SUN 00Z 20-DEC   4.0     3.3     132    7957    16003           0.00    0.00    
SUN 06Z 20-DEC   3.6    -1.7     131    4022    16003           0.03    0.00    
SUN 12Z 20-DEC   3.8     2.8     132    6607    17002     RA    0.06    0.00    
SUN 18Z 20-DEC   6.9     2.6     133    6694    17003           0.08    0.00    
MON 00Z 21-DEC   6.9     0.9     133    5159    18001           0.00    0.00    
MON 06Z 21-DEC   4.1     0.9     132    5363    26002           0.01    0.00    
MON 12Z 21-DEC   4.3     1.0     131    5951    23003           0.00    0.00    
MON 18Z 21-DEC   8.6     2.7     132    6738    24007           0.00    0.00    
TUE 00Z 22-DEC   6.3     0.5     133    5341    27006           0.00    0.00    
TUE 06Z 22-DEC   4.0    -0.3     132    4663    27005           0.00    0.00    
TUE 12Z 22-DEC   0.6    -0.3     130    9494    33003           0.00    0.00    
TUE 18Z 22-DEC   8.3     2.5     131   11103    35004           0.00    0.00    
WED 00Z 23-DEC   3.5     6.8     132   10954    10002           0.00    0.00    
WED 06Z 23-DEC   1.4     9.4     133   10672    16002           0.00    0.00    
WED 12Z 23-DEC   1.4     6.4     132   10389    17005           0.00    0.00    
WED 18Z 23-DEC   9.6     4.3     132    9111    18009           0.00    0.00    
THU 00Z 24-DEC   7.2     4.2     133    7885    16008           0.00    0.00    
THU 06Z 24-DEC   6.2     1.9     132    6131    29003     RA    0.54    0.00    
THU 12Z 24-DEC  -1.6    -7.1     128     176    35006     SN    0.69    0.43    
THU 18Z 24-DEC   0.6   -10.2     128    1124    30011     SN    0.03    0.51    
FRI 00Z 25-DEC  -5.6   -13.4     126       0    30007           0.01    0.49    
FRI 06Z 25-DEC  -9.9   -16.1     124       0    28004           0.00    0.54    
FRI 12Z 25-DEC -11.6   -15.3     124       0    27004           0.00    0.54    

GFS 0.5 Degree FORECAST FOR: BNA LAT= 36.12 LON= -86.68 ELE= 591 12Z DEC18 * - 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) FRI 12Z 18-DEC -2.0 -1.8 129 19 16003 0.00 FRI 18Z 18-DEC 6.1 -0.2 130 9572 16003 0.00 0.00 SAT 00Z 19-DEC 2.4 2.1 132 9583 14004 0.00 0.00 SAT 06Z 19-DEC 1.0 2.3 132 8858 17005 0.00 0.00 SAT 12Z 19-DEC 0.8 2.6 132 7793 17007 0.00 0.00 SAT 18Z 19-DEC 7.9 3.5 132 7298 19010 0.00 0.00 SUN 00Z 20-DEC 6.0 3.4 132 7392 18007 RA 0.00 0.00 SUN 06Z 20-DEC 5.7 1.1 132 6033 17009 0.13 0.00 SUN 12Z 20-DEC 5.8 1.3 132 5492 18005 RA 0.17 0.00 SUN 18Z 20-DEC 9.2 1.2 132 5401 26004 RA 0.01 0.00 MON 00Z 21-DEC 6.0 1.3 132 5378 24002 0.00 0.00 MON 06Z 21-DEC 3.8 0.9 132 5166 23004 0.00 0.00 MON 12Z 21-DEC 2.6 1.3 132 5552 23005 0.00 0.00 MON 18Z 21-DEC 10.2 3.5 133 6404 25013 0.00 0.00 TUE 00Z 22-DEC 6.4 0.3 133 4858 24008 0.00 0.00 TUE 06Z 22-DEC 4.5 -3.4 131 3325 29007 0.00 0.00 TUE 12Z 22-DEC 1.5 -0.2 130 9956 31005 0.00 0.00 TUE 18Z 22-DEC 7.8 3.1 131 10510 02001 0.00 0.00 WED 00Z 23-DEC 4.2 7.7 133 10484 15004 0.00 0.00 WED 06Z 23-DEC 3.4 8.8 134 10559 18007 0.00 0.00 WED 12Z 23-DEC 4.7 8.2 133 9466 18011 0.00 0.00 WED 18Z 23-DEC 9.8 4.4 133 7882 19016 0.00 0.00 THU 00Z 24-DEC 7.7 2.2 133 6420 22009 RA 0.14 0.00 THU 06Z 24-DEC -0.7 -8.3 128 291 35009 SN 0.50 0.27 THU 12Z 24-DEC -3.8 -9.4 128 0 30003 0.01 0.34 THU 18Z 24-DEC -1.0 -13.2 127 221 29012 0.00 0.31 FRI 00Z 25-DEC -5.5 -15.8 125 0 30008 0.01 0.32 FRI 06Z 25-DEC -8.7 -16.6 124 0 29006 0.00 0.32 FRI 12Z 25-DEC -10.1 -16.0 123 0 28006 0.00 0.30   GFS 0.5 Degree FORECAST FOR: TYS LAT= 35.82 LON= -83.98 ELE= 981 12Z DEC18 * - 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) FRI 12Z 18-DEC -2.6 -4.0 128 211 03002 0.00 FRI 18Z 18-DEC 4.7 -1.1 130 4510 05003 0.00 0.00 SAT 00Z 19-DEC 1.4 1.3 131 10188 07002 0.00 0.00 SAT 06Z 19-DEC 0.5 3.0 131 9367 11001 0.00 0.00 SAT 12Z 19-DEC -0.2 2.1 131 8675 15002 0.00 0.00 SAT 18Z 19-DEC 7.2 2.5 132 8381 23003 0.00 0.00 SUN 00Z 20-DEC 4.1 3.0 132 7730 16002 0.00 0.00 SUN 06Z 20-DEC 3.3 -2.0 131 3538 20004 RA 0.01 0.01 SUN 12Z 20-DEC 3.2 1.2 132 5703 10003 RA 0.05 0.03 SUN 18Z 20-DEC 5.0 2.4 132 6242 21001 RA 0.05 0.03 MON 00Z 21-DEC 5.0 1.3 132 5511 19001 RA 0.01 0.03 MON 06Z 21-DEC 4.7 -0.1 132 4671 26003 0.01 0.03 MON 12Z 21-DEC 4.4 -0.2 131 4335 24005 0.00 0.03 MON 18Z 21-DEC 7.5 0.3 132 5400 24009 0.00 0.03 TUE 00Z 22-DEC 6.0 -1.1 132 4265 26008 0.00 0.03 TUE 06Z 22-DEC 3.6 -1.5 131 3866 25007 0.00 0.03 TUE 12Z 22-DEC 0.8 -4.3 130 2072 24003 0.00 0.03 TUE 18Z 22-DEC 7.4 -0.6 131 10304 34001 0.00 0.03 WED 00Z 23-DEC 3.4 3.7 131 10747 08002 0.00 0.03 WED 06Z 23-DEC 1.6 8.5 132 10674 11002 0.00 0.03 WED 12Z 23-DEC 0.8 6.4 132 10481 16002 0.00 0.03 WED 18Z 23-DEC 9.5 4.7 133 9662 21003 0.00 0.01 THU 00Z 24-DEC 7.0 4.3 133 7775 17003 0.00 0.01 THU 06Z 24-DEC 5.2 2.6 132 6376 06002 RA 0.18 0.03 THU 12Z 24-DEC -1.4 -6.5 128 632 32004 SN 0.85 0.24 THU 18Z 24-DEC -1.9 -11.4 127 392 30003 SN 0.27 0.67 FRI 00Z 25-DEC -6.7 -13.7 126 0 29008 0.03 0.69 FRI 06Z 25-DEC -11.6 -17.6 124 0 25005 0.00 0.70 FRI 12Z 25-DEC -13.9 -19.5 123 0 23005 0.00 0.70 I just jinxed everyone..lol

 

 

Man, you didn't jinx us.  Right now we are living through a pandemic and one crazy year...whatever happens, this one is most definitely NOT on you if it fizzles!  LOL.  And thanks for the TRI numbers.

[Holston_River_Rambler]

One thing I do like about this, is that the cold front seems like the real deal. Pretty much universal agreement that a strong cold front associated with a highly amplified trough, is going to sweep through late next week.

[Carvers Gap]

Just now, Holston_River_Rambler said:

One thing I do like about this, is that the cold front seems like the real deal. Pretty much universal agreement that a strong cold front associated with a highly amplified trough, is going to sweep through late next week.

Modeling is showing powerful cold front.  Would not surprise me to see a waver(even two if it slows down), run that front.  That is old school right there.  Might be similar to the earlier system in December but on steroids.  

 

[Holston_River_Rambler]

UKMET looks interesting out to 144:

 

 

Looks like it is pulling the front through and leaving some energy behind, about to swing across TX

[Wurbus]

GEFS has decent representation for this far out as well. I agree that I do like the consistent cold front coming through. This should be a fun one to track over the next 5-6 days.

[Carvers Gap]

7 minutes ago, Holston_River_Rambler said:

UKMET looks interesting out to 144:

 

 

Looks like it is pulling the front through and leaving some energy behind, about to swing across TX

Low in the Lakes is no bueno.  That said, a low near Brownsville with a big front incoming looks poised to make a run.

[Wurbus]

7 minutes ago, Carvers Gap said:

Low in the Lakes is no bueno.  That said, a low near Brownsville with a big front incoming looks poised to make a run.

Doesn't all the models show that low in the Lakes region ahead of the front and then the new low develops in the south along the front?

[tnweathernut]

5 minutes ago, Carvers Gap said:

Low in the Lakes is no bueno.  That said, a low near Brownsville with a big front incoming looks poised to make a run.

Normally, I'd agree with you, but I believe this low is the powerhouse responsible for whipping that cold front through!  We just need the southern low to develop along the front in just the right place as a result of the energy diving toward the Gulf of Mexico.  Sure beats watching a front simply blast through.

[TellicoWx]

Hard to tell on pivotal cause it is on snow depth, but 12z GEFs looks better than 00z...Have they loaded for you Holstons?

[TellicoWx]

UKie at 144 is similar to the CMC vs GFS...GFS is more progressive with the front and secondary low at that point..UKie just further SW with the secondary. LP over the lake is pulling the front thru, all models showing their bias at this range.

[Holston_River_Rambler]

18 minutes ago, TellicoWx said:

...Have they loaded for you Holstons?

 

 

[TellicoWx]

12z 500 vort:

GFS/CMC/UKMET

[Holston_River_Rambler]

I was wondering how much energy was being left behind by the Ukie. My F5 Ukie maps are pretty slow, so that's why I went to Meteorcentre. 

That Ukie map looks lit to me!

[Holston_River_Rambler]

Here's the UKMET precip and H5 vorts:

 

 

The front is really distinct on the precip map, and you can almost see the wave starting to form. I feel like the energy would try to close off or go negative in a good spot for some of us. 

Euro was pretty different than the UKMET yesterday, though. 

[Wurbus]

I'm just going to ignore that Euro run and ride the GFS for the next 5 hours.

[Holston_River_Rambler]

I don't know, it wasn't too bad. Could have looked like the ICON. 

 

[PowellVolz]

I'm just going to ignore that Euro run and ride the GFS for the next 5 hours.

We are in that 5-7 day window where the Euro acts like cousin Eddie with the microwave turned on.


.

[Holston_River_Rambler]

[Carvers Gap]

Guessing the Euro/UKMet are a bit slow wit the energy to our southwest and the GFS a bit too fast.  Blend those solutions, and looks decent to me.  I agree with tnweathernut above in this aspect, that powerhouse low is what is driving the cold front.  Many a winter storm has been born on a trailing cold front - been a while since that has happened here.  Will be interesting to see the ensembles for the Euro in terms of slp locations.

[Holston_River_Rambler]

I suspect there are a few EPS members that look more like the GFS, but won't have access to individual members until after 4 PM. 

 

 

 

 

[TellicoWx]

15 minutes ago, Holston_River_Rambler said:

I suspect there are a few EPS members that look more like the GFS, but won't have access to individual members until after 4 PM. 

 

 

 

 

Just glancing at this, but would bet the EPS is alot more like the GFS than the OP run. Euro OP consolidated the energy over the lakes (bombing the LP there)..EPS mean looks to track the parent LP into SE Canada similar to the GFS...need that separation.

[AMZ8990]

Anything exciting going on guys?  lol 

[John1122]

EPS mean, while not on par with the GFS by any means, would still see a snowy Christmas eve. There are several big dogs and several complete misses on it, as one can expect from a 50 member run 5-6 days out from an event.

[Nash_LSU]

15 minutes ago, Blue Moon said:

We're pretending not to freak out at the slight possibility of a white Christmas.

I'll feel better with more model agreement a few days from now. It always stinks having to rely on cold catching up to moisture. It lets us down more times than it works out, but a man can dream. I'm trying not to let my emotions get in the way of the logical part of my brain that says it's not likely to happen, but...

 

 

[John1122]

The GFS is sticking to it's guns on the change over thumper. Lost the idea of the clipper that follows unfortunately. Still a big run for most of the valley forum. I wish there was a way for the far western areas to be involved, and who knows, maybe there still will be. Long ways to go with this one, and we've seen so many great runs all the way up until nowcast time that folded.

[John1122]

The cold that follows is one of the all time cold Christmas days. Wide spread single digits Christmas morning in the snow areas. Highs in the 10s and lower 20s, by 7pm Christmas evening already widespread temps in the 5 to 10 degree range. Unless SW flow aloft develops overnight into the 26ths, probably going to show up with some sub zero temps.

[TellicoWx]

Down side: 18z GEFs lost most of it's big producers

 

Upside: It's the 18z GEFs lol

 

18z OP dug the energy a little more, slowing the front..but also had the energy more consolidated with the northern LP.

[Daniel Boone]

3 hours ago, John1122 said:

The cold that follows is one of the all time cold Christmas days. Wide spread single digits Christmas morning in the snow areas. Highs in the 10s and lower 20s, by 7pm Christmas evening already widespread temps in the 5 to 10 degree range. Unless SW flow aloft develops overnight into the 26ths, probably going to show up with some sub zero temps.

With pretty much all Data showing the bitter cold blast, weather media outlets are buying into a just cold shot.  Saw one such one, TV Met, go for a high of 36 Christmas . This person generally uses a Euro/GFS blend but, more times than not, the warmest solution.  Carvers probably knows who but, I won't call any names as am not trying to defame them.

      At this juncture, I'll only go as far as to say, it looks a pretty much sure bet of one colder than the run of the mill cold shots like yesterday's. Basically the type some weather outlets are showing. 

       I know many of them adjust to Climatology and also trend downward as the blast continues being progged as we get closer in time. 

       

[John1122]

1 hour ago, Daniel Boone said:

With pretty much all Data showing the bitter cold blast, weather media outlets are buying into a just cold shot.  Saw one such one, TV Met, go for a high of 36 Christmas . This person generally uses a Euro/GFS blend but, more times than not, the warmest solution.  Carvers probably knows who but, I won't call any names as am not trying to defame them.

      At this juncture, I'll only go as far as to say, it looks a pretty much sure bet of one colder than the run of the mill cold shots like yesterday's. Basically the type some weather outlets are showing. 

       I know many of them adjust to Climatology and also trend downward as the blast continues being progged as we get closer in time. 

       

It will really depend on snow cover but I can't imagine highs will be above freezing even without it just based on what's being shown on models.  

[BlunderStorm]

GL low looking more wound up on the 0z GFS. Not as potent cold is brought south but more of it though. The front seems more progressive and enters at less of an angle leaving less of a chance for a second southeastern low to develop in time to bump the totals for the forum region. I like the sight of frontal snow on Christmas Eve but I can't help but fear a bust involving cold chasing rain without a more established low.