Carvers Gap

Surface pressure (Euro Weeklies ext) is very much EPO driven. Cold goes down the front range and spread quickly eastward. The only thing to watch is if modeling tucks that trough under the EPO ridge into the Mountain West. That means cold would come down the west slopes of the Rockies. However, I feel given the time of year that the cold will drain down the front range and race eastward. This is a cold and storm pattern. Precip is normal to above for the forum area during December. This would allow for a January thaw and potentially winter returning later in January. It is a good thing that we are seeing this in November as the winter will often repeat November patterns. This is a 30 day map! That is Alaska cold with a great mechanism to get it south eastward.

This is pretty cold for a 7-day ensemble at range. That means reality could be much colder. Almost 20 degrees below normal at this range is a big number. Now, this could change, and we have seen these looks evaporate or just be a 7-10 days too early. Something to watch, but super impressive. That is an overrunning look if I have ever seen one. Somewhere between I-40 to the Ohio River looks like it could be the track.

Modeling could be a bit too quick, but they generally are showing a very cold regime Dec 1-7 at least.

Good catch. I was thinking this setup is purely PAC driven. That being crazy cold to this area. The 18z ensembles generally supports that look. Edit: Sorry, I though that was the 18z GFS which John notes (Below) is powerful.

@PowellVolz, all right man. Time to jump in!

The 12z Euro AI is just ridiculously cold for day 10-16.

Ladies and Gentlemen, here we go...from MRX this evening. Modeling nailed this from a ways out. That is good, but modeling has more on the table after this. Key Messages: 1. Gusty winds expected across the higher elevations of the southern Appalachian Mountains Wednesday through Saturday. Gusts from 30 to 40 mph will be common. 2. Breezy winds in the lower elevations across the valley Wednesday through Friday. Gusts from 20 to 30 mph will be common. 3. Wind chills in the 30s and 40s for valley locations Thursday and Friday during the day. Wind chills in the teens for the higher elevations of the southern Appalachian Mountains. 4. Light snow accumulations likely across the northeast TN and southwest VA mountains. Amounts of 1 to 2 inches are expected. Isolated 3"+ amounts are probable.. 5. A return to normal temperatures by Sunday. Discussion: Active weather for the back half of the work week, with a shock to the system as we transition fairly quickly from shorts weather to parka weather. Well see a quick-moving weather system passing through the Ohio River Valley to kick things off. Expect the system will move in Wednesday night into Thursday night, bringing with it a blast of colder air as it moves south. Because of this setup, were looking at some light snowfall in our area from Thursday night through Saturday morning. As the weekend progresses, this system will move out and high pressure will start to build back in, bringing temperatures back to normal by Sunday. Snow: Were in for some of our first snowy weather in our higher elevations, and we might even see a few flakes overnight in the valleys of northeast Tennessee and southwest Virginia. The big question is how much moisture well actually get. Right now, it seems like we can expect around 1 to 2 inches of snow in the mountains of northeast Tennessee and southwest Virginia, with some spots possibly getting up to 3 inches. Theres about a 50-75% chance of seeing those higher amounts in isolated areas when looking at probabilistic guidance. Further south, places like Newfound Gap and Mt Leconte are looking at around 0.5 inches of snow due to less moisture. For now, were sticking with these snowfall estimates, but theres still some uncertainty. The actual snowfall could vary quite a bit, from 3 to 5 inches, depending on how much moisture we end up getting and the exact position and strength of the low pressure system to our northeast. Some of the high resolution models are indicating we could see some enhanced moisture off the Great Lakes, which can really increase snow amounts in a narrow area...But just as likely is the low shifts 30 miles to the north and much of the moisture stays across Kentucky and West Virginia. Also complicating the forecast is how warm the ground will be early this week leading into the snowfall which could melt much of it upon contact. Wind: On Wednesday, were looking at some pretty gusty winds as a weather system moves through. Expect winds of 30 to 40 mph across the higher elevations in eastern TN, southwest NC, and southwest VA. As we move into Wednesday night through Saturday morning, those strong west to northwest winds will stick around, keeping the gusts going at 30 to 40 mph in the mountains, with some spots possibly hitting up to 45 mph. It still appears we will remain below High Wind Warning criteria, but a Wind Advisory is still very much in play. On Thursday and Friday afternoons, as the winds mix down to the surface, we`ll also see breezy conditions in the valley areas, with wind gusts from 20 to 30 mph being pretty common. By Saturday, the winds will start to calm down as the weather system moves out to the east. Temperatures: After the cold front moves through on Thursday and Friday, its going to feel a lot more like January. Daytime highs will be chilly, and with the breezy winds, it`ll feel like its in the low to mid-30s for most of the area. In the higher elevations, wind chills will dip into the teens. Keep in mind, these are daytime wind chills, not overnight temperatures. While these wind chills arent out of the ordinary for us, they`ll definitely be a bit of a shock given the recent warm spell. If youre planning to spend time outside, make sure to dress warmly and be prepared for the cold especially the kiddos waiting for the bus in the morning on Thursday and Friday!

Saddle up! Here we go!!! The Weeklies ext(Euro) have the Christmas warm-up, but then they move back to seasonal which is plenty good during early January. I lean warm for winter overall with a cold start. That said, the weaker this ENSO gets....the more we are dealing with an SST forecasting bust which is in progress. If this goes Nada...probably still warm. But....... a weak La Nina has to be accounted for in terms of cold intrusions. It also brings a new set of analogs into play if one uses analogs. I guess what I am saying is that my original forecast is probably busted right now as we speak. If it was Monopoly, I would say, "Bank error in your favor. Go collect $200." This first cold shot could be a one-off. That has certainly been the case for the last few Nina winters....cold until Christmas and then torch. However, in middle and western areas of the forum, winter returned during a couple of winters to historic levels. What I like looking at LR forecasting: -Sometimes we can't get it to snow at all when the cold comes around. In LR modeling, snow is accompanying the cold at varying latitudes east of the MS. -The late landfalling hurricanes do have some correlation to wild winters here. -We haven't had any early season snowfalls...seems to be the kiss of death for bad winters IMBY. -There is cold in North America.\ -I tend to think the EPO is going to be the driver through the first half of winter w/ warm (maybe very warm) interludes. I did NOT think that several weeks ago. However, I think winter is showing a bit of its hand. -If I was going to re-write my winter forecast, it would be similar. HOWEVER, I think winter returns during January. -I have been super uneasy(and have stated that) about this winter. We may struggle to get to La Nina status. Why is that important here? The SER will have trouble holding all winter IMHO. A moderate or strong La Nina? Get out the Bermuda shorts and don't put away the lawn mower. A weak La Nina? Wicked cold to the Apps and beyond w/ maybe even some Piedmont ice/snow. -Bottom line....climatology for weak La Ninas in this area is IMHO the best, single predictor of cold winters here. I will take that ENSO state over all others. And that gives me great, great pause. I still lean warm for winter, but Mother Nature could yank that carpet out at any time. What I don't like: PDO MJO tendencies towards warm phases(but this winter could be one of those that bucks the trend....if my suspicion about the EPO as the driver is correct....the EPO trumps the entire pattern) The cold is just a bit early. I like cold to show up just before or after Christmas. Analog in play: 95-96....Cold came in waves, and snow moved along that boundary at times during the winter. Today's 8-14 analogs: John and Boone can fish the info out of these. I think there are some decent ones in there... 19891217 19561202 19511211 19551214 19761203 20081205 19631213 19611210 19641121 20001207 One last note: The ingredients are there for an early season snowstorm, and maybe more than one. No guarantees, but that is wild given how warm it has been.

Yeah, man! I had it in the queue for you or John or holston. AMZ definitely brings the cold when he starts a thread. December is gonna be a cold thread. Take it to the bank now.

I just want summer to be over before met winter starts!!! LOL.

I was thinking that looked like the strat was getting hammered pretty good. Two lobes at 30mb and 50mb around this timeframe. I don't know if I would call it a split, but definitely looks dislodged. Reading in the MA....I would add to their discussion and say that active Pac jet may be the cause of it.

This is what I am looking at. It was there at 12z, but not this crazy. The 18z GEFS has it as well. The GFS has an uncanny ability of spotting early season cold. I am NOT saying this is going to happen, but it is worth noting even at this range. Just a few snippets from 18z.

That high gets to 1065 I think near the Yukon.

The thing I like, and it is in fantasy land...is that big 1055 high late in the run. When we see those in December, that is a good sign if it verifies. Big highs in Montana will often find their way here as long as they are on the east slopes.