December 2020 Medium/Long Term Pattern Discussion.

[BlunderStorm]

1 minute ago, John1122 said:

The 12z Euro looked like an early December 2009 paste job here that put down 8 inches of heavy wet cement overhead while it rained north, south, east and west of here. For whatever reason this county was just in the perfect spot in the storm and it dropped silver dollars for 5 straight hours. It was mixed slush about 15 miles away in Scott and Whitley County Kentucky but just hammered here. 

Rates will overcome?

[John1122]

GFS moved a little towards the Euro for my back yard. Probably more elevated than my actual back yard. The global models tend to paint a little too broad with their snow output maps. But it does appear likely rate driven dynamically cooled snow falling. Has a dollop of 6 inches a few miles away. 

 

[John1122]

3k NAM hits the Plateau and SE Kentucky pretty decently. Probably cut the snow maps in half with probably 5 or 6:1 ratios at best. 

[John1122]

Sounding on the 3k when snow breaks out here. It was showing near 40 on the regular NAM yesterday. 

 

[John1122]

Euro was similar to the GFS/NAM and it's 12z run with snow over the Plateau/SEKY and even a bit of unelevated Middle Tennessee. Also shows wave two beginning as frozen at times across the area before changing to rain. 

[Holston_River_Rambler]

Overnight ensembles in the fantasy range still look like they want to quickly sweep the trough out of the southwest, and they start to make the Pac look more favorable (GEPS least of the three though):

GEPS:

 

GEFS:

 

EPS:

 

In loftier realms, the strat. continues to stratify. Nothing too dramatic, but still interesting:

The split at 50mb looks like it is going briefly to happen:

 

But the last image in the above, shows it at 10mb. Still pretty wound up.

The temperature maps at 10mb are more interesting to me this AM:

You can see some warming over the pole, but cooler temps look to be trying to wrap back in. One thing that I don't remember noticing before is warming over the North Atlantic. As long as I've been making these strat. gifs (admittedly not very long) the heat flux for warming attempts all have come from Asia and the Bering Sea. It could be that the ever elusive -NAO, which I haven't seen materialize as long as I've been active on weatherboards, is having an effect too this year. 

There does seem to be some connection between the geographic location of the heat fluxes and the -AO and -NAO. I have absolutely no idea if I'm reading this correctly, but it looks to me like the two feed into one another. Reading the above gif like a graph, where the map at the botton is one axis and the hPa heights on the lefty are the other, look above Baffin Island/ Bay it almost looks like the heating that extends down from 1 hPa, to close to 50 hPa is tied to the cooling to its left, cooling that is in part an attempt to balance the larger area of heating above Siberia on the map, and extending down to about 50 hPa too. 

Now go back and look at the temps on the Euro's depiction of the SPV at 10 mb above, see how the warmer areas correspond. I'm hoping that there is some kind of precarious balance in this inbalance that can at least keep the SPV from dominating this winter. 

 

 

Further south Maritime Continent convection looks sort of healthy, but a lot of it is south of the equator, which, I believe should mute its impact.

Hopefully that batch north of the equator, between 160 and 170 (with a little trailing back to 190) degrees longitude can kick it up a notch and help us out. 

There is some convection over the Eastern Indian Ocean that does appear to be adding some...not sure what the right word here is... momentum? maybe... to the N. Hemishpere's flow:

You can also see that in this chart:

You can see the bigger wave over N. Australia, just SE Darwin, and that is likely why the SOI (determined from looking at the differences between the MSLP between Darwin and Tahiti (look at all the sinking air there) is ~15 today. But again, all that OLR near Darwin is S. of the equator, so notice the arrows indicating divergent winds, all aimed S or SE. Looking at the MJO this way, you can see why it's in the COD. Conflicting, and weak, signals. 

 

Still happy with Ventrice's projections, which would show it getting more into the W. Pacific.:

 

[weathertree4u]

1 hour ago, Holston_River_Rambler said:

Overnight ensembles in the fantasy range still look like they want to quickly sweep the trough out of the southwest, and they start to make the Pac look more favorable (GEPS least of the three though):

GEPS:

 

GEFS:

 

EPS:

 

In loftier realms, the strat. continues to stratify. Nothing too dramatic, but still interesting:

The split at 50mb looks like it is going briefly to happen:

 

But the last image in the above, shows it at 10mb. Still pretty wound up.

The temperature maps at 10mb are more interesting to me this AM:

You can see some warming over the pole, but cooler temps look to be trying to wrap back in. One thing that I don't remember noticing before is warming over the North Atlantic. As long as I've been making these strat. gifs (admittedly not very long) the heat flux for warming attempts all have come from Asia and the Bering Sea. It could be that the ever elusive -NAO, which I haven't seen materialize as long as I've been active on weatherboards, is having an effect too this year. 

There does seem to be some connection between the geographic location of the heat fluxes and the -AO and -NAO. I have absolutely no idea if I'm reading this correctly, but it looks to me like the two feed into one another. Reading the above gif like a graph, where the map at the botton is one axis and the hPa heights on the lefty are the other, look above Baffin Island/ Bay it almost looks like the heating that extends down from 1 hPa, to close to 50 hPa is tied to the cooling to its left, cooling that is in part an attempt to balance the larger area of heating above Siberia on the map, and extending down to about 50 hPa too. 

Now go back and look at the temps on the Euro's depiction of the SPV at 10 mb above, see how the warmer areas correspond. I'm hoping that there is some kind of precarious balance in this inbalance that can at least keep the SPV from dominating this winter. 

 

 

Further south Maritime Continent convection looks sort of healthy, but a lot of it is south of the equator, which, I believe should mute its impact.

Hopefully that batch north of the equator, between 160 and 170 (with a little trailing back to 190) degrees longitude can kick it up a notch and help us out. 

There is some convection over the Eastern Indian Ocean that does appear to be adding some...not sure what the right word here is... momentum? maybe... to the N. Hemishpere's flow:

You can also see that in this chart:

You can see the bigger wave over N. Australia, just SE Darwin, and that is likely why the SOI (determined from looking at the differences between the MSLP between Darwin and Tahiti (look at all the sinking air there) is ~15 today. But again, all that OLR near Darwin is S. of the equator, so notice the arrows indicating divergent winds, all aimed S or SE. Looking at the MJO this way, you can see why it's in the COD. Conflicting, and weak, signals. 

 

Still happy with Ventrice's projections, which would show it getting more into the W. Pacific.:

 

I am just happy to not see such warm temps this December; hopefully we can at least have a normal Winter season this year, a couple of snows would be a bonus, just cannot stand another year of mid 60's in January~

[Carvers Gap]

@John1122, we have even had snow during mid-early December.  I think twice during the last 11 years, 09-10 and a couple of years ago.  I think the December snow days a couple of years ago were Kingsport's first in nearly four decades(could be more).  Those were both really big snows.   I think you have noted that early season storms seems to be the trend of late.

 

[Carvers Gap]

Just looking at the LR, really nothing new. There are some hints the Pacific may get its act together during the first part of January - CFSv2 extended.  The run of the GEFS extended breaks down the pattern in early Jan, but then WxBell stops the run.  WxBell has been really "buggy" for the past few weeks.   For you all using pay sites, who are you using?  I am not unhappy with WxBell, but if the site continues to be buggy I will take my business elsewhere.  

I think we are going to have to have a resupply of cold air if we are going to get a forum wide storm at lower elevations.  Though currently, the 0z CMC and 6z GFS do imply ice for NE TN for the second storm.  Holston, that second storm indeed looks like a Miller B on some models and those usually bring rain to the forum area.  For the models which don't have energy transfer(or have less), NE TN sees ice or snow or both.  Not sure I buy ice here (at least for extended amounts of time).  We do get light icing at times if the storm moves in during an inversion, but that usually gets scoured before serious damage is done.  Models often make the mistake of bleeding cold air into the TRI from the NE when the mountains usually just won't allow it.  Sometimes it can get to Abingdon, but that is about it.  

I will add that when DC gets in the slot for snow, often snow accumulations will begin in NE TN and work NE into the Mid-Atlantic.  So, for the extreme NE TN corner...these have to be watched.  Just depends on how quickly that low gets its act together.

[Holston_River_Rambler]

I’m not entirely convinced the second one has moved as far south as it will. Some of the EPS members looked better than the OP for TRI and the 6z Euro continued the trend with the energy nudging just a tad more south as it drops over the southwest. But yeah, that line somewhere between Wytheville and Marion is usually the cut off. Y’all did pretty good with something like this in Dec. 2018, right? I think my parents in Ridgefields right on the Holstein (probably one of the warmest areas in Sullivan county) got maybe 8 inches. 
 

That HP is so close to being in sync with the Low, but just a little too far ahead of it to keep everything south. 
 

hopefully as winter goes on we can get more highs to start dropping down if cold can keep building in Canada. 

[Holston_River_Rambler]

God bless the CMC, it's really trying to help some of us out. 

[Holston_River_Rambler]

I don't know what the Euro is smoking, but I'm going to drive up to Huntsville and Oneida Monday AM, to see if anything like this verifies:

 

[John1122]

16 minutes ago, Holston_River_Rambler said:

I don't know what the Euro is smoking, but I'm going to drive up to Huntsville and Oneida Monday AM, to see if anything like this verifies:

 

Its dumping right on my head right there. It's insistent on that happening for multiple runs in a row. 

[Holston_River_Rambler]

1 minute ago, John1122 said:

Its dumping right on my head right there. It's insistent on that happening for multiple runs in a row. 

I hope it does. I guess I'm just in a bearish mood right now and won't believe it until I see it. 

[John1122]

Just now, Holston_River_Rambler said:

I hope it does. I guess I'm just in a bearish mood right now and won't believe it until I see it. 

I'm skeptical too. I guess it's rate driven and that's allowing it to get below 3000 feet and stay snow on the Euro. 

[Holston_River_Rambler]

Yeah, it looked like it was the heaviest precip contour on weathermodels. Really heavy precip has def. been consistent across most models. 

[Daniel Boone]

Over the last 10 years,  many places snowfall averages have decreased.  However, one area that has gone against that trend is Oklahoma. There was a time when Tulsa and Oklahoma Cities Snowfall averages were quite a bit lower than ours. 

      What has led to this "switch" ? Is it the warm Atlantic cycle, mostly +NAO,  or other ? 

[Carvers Gap]

Now, what the EPS is cooking up at lunch will play.  PNA ridge after 300.

[jaxjagman]

Man that is so close

 

ECMWF Deterministic FORECAST FOR: BNA    LAT=  36.12 LON=  -86.68 ELE=   591

                                            12Z DEC12
                 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) 
SAT 12Z 12-DEC  13.4     8.0     136    8240    19011                           
SAT 18Z 12-DEC  15.9     8.1     136    9142    22008                           
SUN 00Z 13-DEC  11.5     5.9     135    9959    26005           0.01            
SUN 06Z 13-DEC   6.0     5.1     133    9805    27002           0.00            
SUN 12Z 13-DEC   2.7     5.9     132    9473    33003           0.00            
SUN 18Z 13-DEC  11.1     5.5     133    9139    26002           0.00            
MON 00Z 14-DEC   7.8     2.5     133    5817    36003           0.03            
MON 06Z 14-DEC   5.1     0.8     131    6486    01006           1.02            
MON 12Z 14-DEC   3.3    -1.0     130    1501    34008           0.56            
MON 18Z 14-DEC   5.9    -0.4     130    5006    35006           0.00            
TUE 00Z 15-DEC   2.5    -0.4     130    8922    35006           0.00 

[jaxjagman]

 

Such a stinkin' waste with the AO with a crappie PNA

[Holston_River_Rambler]

35 minutes ago, jaxjagman said:

Man that is so close

18z 3km NAM actually tries to change y'all over before the end.

 

 

[Carvers Gap]

Bout the only thing I have tonight after looking at a very boring set of ensembles and operationals going out to two weeks...the MJO has surged into phase 4.  The CA OLR map really looks like the MJO is heading for phases 7 and 8 after that.  So, this may sound weird, but I sort of want the MJO to gain a bit of amplitude and rotate on around - looks like a real possibility.   That would imply the PNA(which we are seeing return on some LR modeling) might be a factor in a couple of weeks - when it is great climo for cold.   

[Carvers Gap]

CFSv2 heads to colder phases which is likely why it is so cold.  Definitely was a bias of this model last year, BUT it is not an unreasonable option.  It also illustrates where the pattern "could" go if the MJO were to head to 7, 8, and 1.  

[John1122]

3k NAM is rolling in hot for the west and mid Valley. 

[John1122]

That purple in the deep blue is some 40dbz+ snow. 

 

[John1122]

Ends up here. Would be a true paste job on trees and powerlines. Comes at a good time of day. 

[John1122]

12k NAM isn't far off from the 3k, it just doesn't handle the dynamic precip areas as finely as the 3k. Will have to see if they are just NAMing but it's been a big shift towards winter weather over the last two days.  

[PowellVolz]

12k NAM isn't far off from the 3k, it just doesn't handle the dynamic precip areas as finely as the 3k. Will have to see if they are just NAMing but it's been a big shift towards winter weather over the last two days.  

Talking Wednesday here?


.

[TellicoWx]

18z GFS run pretty much sums up last several years of winters for TN...entire state is a snowhole lol

[Carvers Gap]

2 minutes ago, TellicoWx said:

18z GFS run pretty much sums up last several years of winters for TN...entire state is a snowhole lol

Saw the same thing and laughed.  Bout the only positive from that which I see, is that it must be cold for it to snow that far south....plenty of time for that to trend NW, right?