Carvers Gap

Heavy snow shower just moved through w/ snow riding 30mph winds! Crazy wx out there.

Man. And you know that isn't warm either!!!!

Wind is absolutely howling here. Pretty sure I am going to have to reset some Christmas lights.

Most of this in our sub forum falls later in the run...special zoom-in of the GEPS for TRI peeps. Decent numbers this far out.

Modeling during the past 3-4 days regarding the MJO and warmth.............

PNA for the win? We really don't need all of Canada to be cold with the set-up being modeled which is about ten days out(not months or weeks). We need Quebec to be cold, and it is likely going to be. While the rest of Canada is warm, Quebec is the fridge so far this winter. Ensembles are cooling off quite a bit right around the 28th or even earlier. I don't know if the BN heights in the SE are transient or semi-stationary around that time - proceed with caution. MJO plots are hinting at a stall in cold phases, but that is likely the same error from a couple of weeks ago where modeling tried to end the MJO before reaching the cold phases - that looks to be a really bad error/bias in modeling(underestimating the MJO pulse's ability to keep going). Honestly, I would be really surprised if we don't snow snow IF, IF, IF that verifies. And you haven't heard me say that for E TN in quite a while. That is a really wintry pattern on ensembles, and the 12z GEFS looks as bullish as the EPS yesterday.

I know, right!

The 6z GFS is one possibility of where this pattern may go.

Whoever wrote this....we need the "one of us!" GIF. Gives a shoutout to our SE folks - I like that.

And a general rule of systems which dive into the wake of systems departing the EC...they tend to trend north. However, this could be a very impressive system in the TN/NC Apps above 3,000'.

Depends on the year. Knoxville has done much better than MBY for at least two of the last three years, and I am in TRI. We have had a decent number of La Nina's during the last 15 years, and that shifts backside snows well west as many storms cut right across us. Winter has been more a longitudinal algorithm in this forum during the past three years with La Nina. When I lived in Knoxville during the 90s, outside of about three winters, we got very little snow at all (92-93, 93-94, 95-96). Knoxville has done much better of late. As for backside snows, I would almost say it is a lack of Miller A's and NA0 blocking...that may be changing as it "seems" we are seeing the Atlantic move to more negative cycle of NAOs(nothing scientific....just might overall abs). When you see DC in a snow drought, that is probably correlated to what we are seeing here w/ fewer backside snows.

All of that said, the EPS needs full support from the GEFS before I am on board. Again, it is just a share. The EPS has flipped on a dime more that once this winter. I still have whiplash from the last one. LOL.

MRX mentioned blizzard conditions and very low visibility for higher elevations. @fountainguy97 was feeling bad for starting a thread, but that deserves a thread for sure. I just posted the MRX disco in the event thread for it. Crazy.

You folks at higher elevations better hang on tight tomorrow night.

WxBell

Fountain, they(MRX) just said that blizzard conditions might exist at higher elevation. You bet, this deserves a thread! You won't see that mentioned often during afternoon disco!!! Tomorrow A lull in activity is expected in the morning hours as the exiting low moves up the coast. By the afternoon hours, a shortwave trough digging through the Ohio Valley will bring very strong northwesterly flow enhancing snowfall for the higher elevations. Snow totals have not changed much since the last package. Light snow accumulations below half an inch will be possible for the lower elevations of NE Tennessee and SW Virginia, East Tennessee foothills and Upper Cumberland Plateau counties. The best window for snow accumulations will be Monday afternoon and evening with northwesterly 850 mb winds of 35 to 40 kt causing terrain forcing. Snow in the lower elevations of NE Tennessee will have a harder time accumulating with snow starting in the afternoon when temps are still above freezing. Temps will drop quickly in late afternoon and evening but the window for accumulation will be fairly short tomorrow evening. For East TN mountains: Total snow accumulations of 2 to 4 inches possible above 3,000 feet and 4 to 6 inches above 5,000 feet. Total snow accumulations of 1 to 3 inches above 2,000 feet. For Virginia counties: Total snow accumulations of up to 1 inch in the lower elevations and in the higher elevations up to 3 inches. Another round of strong winds expected Monday morning through the evening, mainly in the higher elevations. A strong shortwave digging into the region will bring a strong 850 mb jet from the northwest. In addition to terrain forced snowfall, this jet will likely bring Advisory level winds in the higher elevations. Gusts up to 50 mph are likely in the higher elevations of East Tennessee. Gusts up to 40 mph are possible in higher elevations of SW Virginia. This jet will likely peak around 40 knots in SW Virginia and East Tennessee late Monday afternoon and evening. There may be a window for blizzard conditions in the higher elevations of East Tennessee and SW Virginia during that peak late Monday afternoon and evening. Blowing snow may reduce visibility significantly at times making driving conditions very dangerous.

I don't want to raise expectations with cherry picking models, but that looks pretty similar (more extreme for sure) to other ensembles. But yeah.....that is an insane run for an ensemble. Again, no idea if true....but that would tap the GOM w/ BN temps over much of the SE and MA. The GEFS is not there, but similar. That is how multi-day overrunning events look at range. Huge grains of salt...as usual.

No idea if correct, but I thought that I would share! LOL.

Wow. The 12z EPS is now depicting a fairly decent winter wx patter for the last five days of its run which is the last four days of December and NYD. Here is the last 5 day 500 map and the very last day of that run. That will work. We are not looking at Weeklies now. Oddly, this is what the original weeklies sort of had. Textbook Nino BN heights over the SE. Maybe it is a bit overdone, but we are now entering the timeframe when the EPS is respectable - meaning no shoulder season. That would be quite cold under those BN heights. The GEFS is less impressed but is a similar setup. But man, that is impressive below.

LOL. Ha! I forgot about that. But yes, it sure did!

From MRX... By 12z Monday morning northwest flow will be ongoing as strong coastal storm lifts north from the NC coastline. Meanwhile a strong upper low will develop over Wisconsin and track eastward through the Great Lakes as the day wears on. Embedded within this deepening upper low/trough will be a vort max that will dive southeast from Indiana through the Ohio and Tennessee valleys during the afternoon hours. As this swings through the region, model soundings show deepening moisture and a rapidly cooling thermal profile that will be sufficient to produce snow showers down to the valley floor by late Mon afternoon. The uncertainty that still exists, and it is not insignificant I should add, is just how far south and how widespread any precipitation/snow showers will be. The trends over the last 48 hours have been to continue to pull the precip further and further north, and also to increasingly show a more shallow moist layer to work with for any precip generation. Given we`ll be positioned beneath the left exit region of an H3 jet streak overhead, and the vort max will traverse the northern 2/3 of our forecast area, it seems unlikely that showers won`t be present for much of the area Monday afternoon. However, this seems like a high PoP and low QPF scenario, so while high PoPs don`t necessarily reflect the northward shifts in guidance, I think the QPF and resulting snow accumulations for the most part do. The NAM model soundings show saturation extending into the DGZ by roughly 21z Mon afternoon at Tri Cities, with those conditions continuing until roughly 06z Tue before moisture begins to wane and snowfall potential transitions to an almost entirely orographically induced NW flow regime. The GFS soundings aren`t quite as generous on the moisture side but show similar conditions. In line with the northward shift in moisture and snow potential, model soundings don`t show much in the way of a snow sounding at KTYS during much of the afternoon and evening hours due to lack of moisture. It`s possible we could see a tenth or two of snow accumulation in the valley as far south as the Knoxville metro area, but the best chances for any low elevation accumulations will definitely be in the northern TN valley and even then less than an inch is expected. Otherwise, forecast amounts remain largely unchanged. Amounts of 1- 3" are expected above roughly 1,500 ft in elevation for locations in southwest Virginia and the east Tennessee mountains, with amounts in the 3-5" range limited to elevations above 3,000 ft in those same areas. While some northwest flow snow showers will linger in the higher terrain into Tuesday morning, in large part snowfall will begin to taper off late Monday night. Lastly, before moving on from the wintry precip on Monday, it`s worth pointing the possibility of some possible mixed precip or even outright icing in the higher elevations on Monday. As mentioned in the short term section above, some higher elevations will see temperatures fall below freezing during the morning hours while in a very shallow moist layer that will not extend into the dendritic growth zone until the afternoon. We don`t see a lot of freezing rain, but it`s hard to ignore guidance like the SPC HREF pointing out some potential for freezing drizzle or freezing rain during the morning hours on Monday when other forecast sounding sources support it. Have a feeling that accumulations would be limited at best; likely would wind up having a lot of ice on the trees thanks to increasingly strong (upwards of 30kt) northwesterly H85 flow during the day. This would be for areas between roughly 2,000 ft and 4,000 ft ASL for a short while Monday morning.

Both the 12z RGEM and 3k NAM have decent streamers for the Apps. The overall energy is a bit further north on modeling today, but not absent.

Happy hour of the 18z is winter. Is it right? It is happy hour, but I just hope the 18z passes the bottle to the next run!

Long range ensembles look pretty decent regarding snows for eastern NA, especially just to either side of the Apps. That pattern begins about Dec 28, and is moving up in time. Transition should be Christmas week. This storm should break things up. One more ridge rolls though and then maybe 7-10 days of seasonal temps or slightly BN.