December 2020 Medium/Long Term Pattern Discussion.

[TellicoWx]

0z Euro

[John1122]

7 minutes ago, TellicoWx said:

0z Euro

The model dosey do. The GFS  steps up, the Euro steps back, then they reverse. 

[jaxjagman]

Probably wait and see,it does look like the heights are going to rise in East Asia the next few days followed by a cool down.The AO seems all over the place today towards the New Year today

 

 

[TellicoWx]

UKie/Euro OP now developing a lee side low similar to what the GFS had been doing. Several studies in the past couple decades  have centered around mountain ranges assisting in low development...models tend to struggle somewhat when this occurs. Winds have to hit and ascend at just the right angle or you end up with a plain fropa.

[jaxjagman]

[John1122]

The ratio'd euro is much more impressive. Widespread 6+ in the East. 8-10 N plateau. 2-4 mid state. 

[John1122]

Ratio'd Euro. 

 

[jaxjagman]

Nothing more than a dusting for us at best,rain before hand and surface temps will crush those totals away for us.better than nothing

[John1122]

MRX playing it cautious. Basically the standard "well, it's probably going to snow in the mountains." disco. Can't really blame them though they did put out a giant graphic yesterday talking about a wintry Christmas.

[John1122]

Strangely, and in defiance of literally every single model run for the past 4 days across every single model and ensemble suite, it actually has my snow chances as lower than Knoxville's and I dropped from 60 percent to 40 percent for Christmas Eve night. No clue on what to make of that one.

[John1122]

The 06z GFS is super progressive so far. Has snow breaking out in the northern mid-state by 1am Christmas eve morning. Hammering the I-75 corridor by 7am.

[John1122]

It's showing the odd fingers of accumulation that the ensembles have been showing, this run. Not really sure how that would happen to be honest.

[John1122]

Ends up here after another spoke of energy gives a bit more accumulation to some of the area. Can't imagine there will be strips of heavy accumulations and random blank spots in the actual event but who knows. 

[weathertree4u]

49 minutes ago, John1122 said:

MRX playing it cautious. Basically the standard "well, it's probably going to snow in the mountains." disco. Can't really blame them though they did put out a giant graphic yesterday talking about a wintry Christmas.

Nashville doing the same, pretty standard operating procedure, usually play it ultra safe often times - Nashville - not calling for accumulating snow until they see it snowing and accumulating lol

[John1122]

GEFS is more smoothed and better for most areas vs the OP. I actually do better on the OP but this looks more reasonable overall and I'd prefer this to be closer to reality.

[Holston_River_Rambler]

4 hours ago, John1122 said:

I think Holston has found at times if convection flares even briefly in MJO regions that are warm, the next GFS run goes bad at 500mb

There is a a pretty big blob of convection in the 5 region, in the South China Sea (apparently that one is part of an Invest or Depression, or whatever they are called these days):

 

Also a pretty decent chunk of it over the central Indian Ocean, but nothing to really write home about there:

 

In terms of the OPs, it'll be interesting for me to watch if this big -ve NAO develops and retrogrades, as the wxtwittersphere is suggesting. I've never seen one like this one actually work out, so no clue how the OPs will look if that plays out. 

 

 

[Holston_River_Rambler]

I'm a pretty big fan of the Ukie and Euro's evolution of this week's system ay H5, (especially the Ukie's). Can we just go ahead and lock that in and not have a 200 mile NW jump last minute?

 

Euro:

 

Ukie:

[bearman]

53 minutes ago, John1122 said:

Ends up here after another spoke of energy gives a bit more accumulation to some of the area. Can't imagine there will be strips of heavy accumulations and random blank spots in the actual event but who knows. 

The only thing that gives it credence is that that "random" blank spot in Knox  county is right over my house in Cedar Bluff.

[John1122]

I'd say we are about 12z runs today away from starting a thread for the Christmas event. It's been consistent on modeling for days and the event is getting close to moving onto HI-Res model territory.

[weathertree4u]

Just now, John1122 said:

I'd say we are about 12z runs today away from starting a thread for the Christmas event. It's been consistent on modeling for days and the event is getting close to moving onto HI-Res model territory.

I am just pleased to see something to track this season!

[Carvers Gap]

Liking that the Euro and GFS are back with a storm....Bigger deal is they are both now showing a stronger push of cold air.  The Euro was missing that a few runs ago.  The 0z Euro had some anomalies of -25 below normal(not an actual temp) over the eastern valley with highs in the mid 20s north of I40 and from points east of Nashville.  Chattanooga may not get out of the low to mid 30s according to the 0z Euro on Christmas Day - unless their highs at midnight are warm(temps rapidly dropping throughout the day).   The 6z GFS is much colder with temps in the single digits to lower teens on Christmas morning in NE TN with temps not getting out of the teens during the day.  Christmas night is very gold on the Canadian and American models.  It seemed yesterday that the storm was weaker when the cold was not as expansive or severe.  Something to watch.

[TellicoWx]

I like where we are at currently, still a lot of boom or bust potential so to speak. Upside, at H5 most the modeling is holding the energy back to the sw compared to the more progressive GFS. Also, the depth and degree of the cold shown will lead to some high ratios (even with the GFS setup, atmos will squeeze out all the moisture it can). Downside, if the GFS is correct with it's more progressive solution (consolidating at the lakes vs a strong spoke of energy rotating thru and enhancing the Lee side), we end up with a light event...Regardless, it will be nice to see flakes on Christmas..we all know how rare that is. Next 24-36 hrs will be interesting to watch at H5.

[TellicoWx]

12z GFS still onboard

[McMinnWx]

Mercy. 5.5 for Athens?!

[snowbird1230]

13 minutes ago, McMinnWx said:

Mercy. 5.5 for Athens?!

Yeah thats kinda screwed up..it shows much smaller amounts just to east of Athens once in the mountains of NC..That will not play out that way.

[TellicoWx]

12z GEFS keeps improving

[BlunderStorm]

33 minutes ago, TellicoWx said:

12z GEFS keeps improving

I've often wondered if they or another modeling site could implement a map of median snowfall among all the ensemble members for a run. It would prevent distortion from weenie maps and eliminate a lot of wide expanses of sub-inch totals. A single member with snowfall using the average means that areas will be listed with snowfall despite the vast majority of members having it out of the equation. Granted, the mean is still valuable in it's own right showing low likelihood areas still in play.

[Holston_River_Rambler]

UKMET was pretty ugly. But it has been bouncing around a lot with each run. That being said, it is not an unreasonable way the storm could play out. Low develops on the front and tracks right over east TN and a just in time change over for eastern KY. 
 

[Holston_River_Rambler]

While we're waiting on Dr. Schmaybe, here is something for you strat junkies:

[PowellVolz]

UKMET was pretty ugly. But it has been bouncing around a lot with each run. That being said, it is not an unreasonable way the storm could play out. Low develops on the front and tracks right over east TN and a just in time change over for eastern KY. 
 

This is my main concern. Lows that develop on boundaries love the west side of the apps


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