Carvers Gap

The 6z GEFS and 0z EPS are worlds apart....maybe light years. They eventually get to the same point...but those roads diverge mightily before reconverting in the LR. I think their handling of the MJO is crucial. While I like the GEFS in finding cold, when the EPS gets inside of d10 it outperforms the GEFS. One models is going to be left looking pretty bad after this bout...If one can scrounge up some commonalities: 1. EPO ridge returns late in each run. NAO weakens quickly just like last time. I do wonder if it eventually fires once Nino climatology is a little less hostile. 2. Ridge comes east with wildly different depictions of its duration(I lean longer than the GEFS...) 3. Lots of rain and Pacific air. Lots of sloppy whether which is a hallmark of El Ninos in this area. 4. Lots of whiplash with a wide range of outcomes possible even during the mid-range.

Yeah, agree. Just the look in the eastern Indian Ocean...plenty of convection. I think the IOD index had been falling as of yesterday. That said, the actual satellite photo is pretty steam in that area. That is part of the reason that I think we get consistent(winter type stuff) during the just prior to mid-January.

If is crazy how the overnight run of the EPS is warm and the 12z is cold. This oddity has been going on for weeks. Looked like the NAO might be lost but the EPO reforms. I think we have seen this movie before. The run wasn't cold, but if it continues to correct...even normal temps in late December are formidable as Jeff noted. EPS and GEFS look good at 12z. I wonder how many times I have typed that during December...only to type that the overnight ensembles took a step back. LOL.

Does not appear this is going to be one of those winters where we a bored...lots to figure out. Also, seems to be one of those winters where events can sneak up on us...especially cold fronts. Great discussion by everyone. And I do think we get a nice period of winter weather eventuall. Lots of cold running around and poor model verification after about d8, even with generalities.

Just now getting caught up on model runs since 12z yesterday...been painting most of the week. The GEFS and EPS are worlds apart regarding the ridge placement and duration in the East in the LR. Just when I think they have their act together...the 0z suite happens. A couple of folks have asked what the scientific argument for warm would be(not saying this will happen), but here they are: 1. Ninos have clusters of warm Decembers. 2. The MJO on the JAMSTEC yesterday showed rain in the MJO regions of 4, 5, and 6 in the LR. 3. The Pacific(if the modeling is correct) is about to be less than favorable for at least ten days - hostile is an appropriate word. For the NAO to really work its magic and produce a memorable pattern, those two need to be in sync. 4. The PV might(if the models are correct) indeed tighten up after this minor/moderate PV split. Those four aforementioned reasons are solid reasons. Reasons to think that the LR pattern will be good(wintry)... 1. November...was a great month in terms of weather patterns. What happens in November, the winter will remember. 2. Blocking is showing up on global ensembles. The GEFS and GEPS this morning do indeed depict a workable eastern pattern. The EPS shows how the pattern could go poorly, even with Atlantic blocking - the EPS has played catch-up since October when blocking begins to show-up. 3. The NAO is turning suddenly negative. That often happens. Many have noted on various sub-forums that the NAO doesn't give a lot of notice when it flips negative. It is likely models don't have this worked out yet if real. That said, modeling showed a great -NAO just a few weeks ago that looked golden...and lasted less than a week. 4. The QBO is dropping which should enhance blocking. 6. The pattern should turn colder due to climatology during January/February. Wild Cards... 1. IOD...dropping sharply but will it maintain that? 2. The SOI has been flirting with positive at times. A few very negative days back in November are keeping the 30 day average more negative than it probably is. The big cold snap during November coincided with a sharp drop in the SOI. 3. Storm track. Hate to say waisted...but we have indeed waisted a great storm track of SLPs from the GOM that have been rainers. Will that great storm track continue? Have to think if it does continue...one of those big cold highs will be money. The frequency of precip events will definitely help our odds of snow. 4. Does the GEFS stay on its hot streak of finding cold...or does its remarkable cold bias make it unusable during all but early and late winter? 5. What in the world has happened to LR/seasonal modeling during the past couple of years? Seems like they used to be much more accurate. I am sure there is a statistic that say they are accurate....but the Weeklies are a shadow of their former selves IMHO. Will they improve as the season settles down? Where do we go from here? TRI sits at +1.2F for the month. With a sixty degree high forecast for next week, have to think that holds strong. I think December finishes AN for temps. It is an outside possibility that TRI could get in the mix for the storm around the 22nd. Right now looks like a Miller B. I have noticed over the years, that when DC gets that set-up, often TRI is where the snow axis begins. Right now, just looks too warm. I still feel that beginning Monday, the pattern is 3-5 weeks weeks from getting into a true winter pattern that is both cold and snowy. Again, it can and does snow during a warm pattern. I probably lean towards the three week end of that window. I think the GEFS is likely correct this morning, but just too fast. So, late in the first week of January or second week of January would be a guess as to when we see the a true winter time pattern - not that this week was a bad one. And that is worth stating again, the weather pattern has been decent. Definitely looking forward to see how modeling works out things during the next couple of weeks.

Had a post on in the queue about how warm the models looked this morning. Got busy and forgot to post it! It would have looked something like this about now.

For NE TN folks...I think this is not a huge event, but any ZR is a pain in the neck so heads up. Modeling has hinted at this on an off for several days. Special Weather Statement National Weather Service Morristown TN 358 AM EST Thu Dec 12 2019 TNZ015>018-042>047-VAZ001-002-005-006-008-122115- Hancock-Hawkins-Sullivan-Johnson-Northwest Greene- Southeast Greene-Washington-Unicoi-Northwest Carter- Southeast Carter-Lee-Wise-Scott-Russell- Including the cities of Evanston, Sneedville, Treadway, Kyles Ford, Mooresburg, Kingsport, Bristol TN, South Holston Dam, Doeville, Mountain City, Neva, Shady Valley, Trade, Laurel Bloomery, Greeneville, Cedar Creek, Johnson City, Erwin, Unicoi, Limestone Cove, Elizabethton, Hampton, Rose Hill, Big Stone Gap, Norton, Wise, Coeburn, Appalachia, Pardee, Hiltons, Hansonville, Lebanon, Dye, Castlewood, Honaker, Rosedale, Benhams, Bristol VA, and Abingdon 358 AM EST Thu Dec 12 2019 ...BRIEF PERIOD OF FREEZING RAIN POSSIBLE LATE TONIGHT ACROSS SOUTHWEST VIRGINIA AND PARTS OF NORTHEAST TENNESSEE... Rainfall will spread north across northeastern Tennessee and southwest Virginia beginning around midnight tonight. As it begins, temperatures are expected to be around or slightly below freezing, but will rise slowly through the night as rain persists. This will result in a four to six hour window of freezing rain or a mix of rain and freezing rain. Ice accumulations are expected to be light, generally only a hundredth or two. But travel conditions could become hazardous a brief time, especially across elevated surfaces like bridges and overpasses, as well as secondary roads. The highest impacts will likely be in southwest Virginia where freezing temperatures will persist the longest. Temperatures should quickly rise above freezing around daybreak, ending any threat of freezing rain and quickly improving travel conditions.

One of these days I am going to go in there when everyone gets a universal dusting and plug-in 13" of snow...

Looks like I had around ~.75" of snow. Could have been a hair more or less than that. Tough to tell. Great to see folks getting in some early season snow. I though the models handled the precip pattern pretty well. No model was overly enthused about amounts over NE TN, and indeed, amounts were fairly light IMBY. Models definitely favored a good thump for those to my west, and indeed, that worked out fairly well. I will add that the roads started getting a little icy around 7:30, but better now. It was great to see all of the reports and pics. It was also great to see all of the new folks and forum participation for this. Another fun event!

To really grasp how much models have moved this AM in the d10-15, look at the BN height change over Alaska in the GEPS and EPS. The GEPS is back to a favorable pattern already, and one might imagine that the EPS wasn't far behind it. So, two really strong biases that are making LR ideas difficult to formulate: 1. The GEFS is too cold in the LR, but it seems to spot cold shots...just have to remember they won't be as cold as modeled - usually. In some cases, the GFS has nailed big highs from way out during the past few months. 2. The EPS is nearly blind to cold shots after d10, and just tough to believe any warm-up that actually occurs in that time frame. A warm-up will happen, but a broken clock is right twice a day(meaning if it stays warm in that time frame...at some point it will be right). Right now, I do believe once inside d10, the Euro/EPS is the better model. So right now, my combo would by the Euro/EPS suite inside of d10 and the GFS/GEFS(with cold bias accounted for) after d10. @jaxjagman, so is modeling today showing a SPV disturbance(edit...I must be just waking up as well!)in today's modeling? I haven't looked. I know yesterday folks were talking about potential records.

I should clarify...the SPV. The PV in the troposphere(TPV) does play a part in our winter weather.

Biggest thing is that there are a lot of mixed signals in the LR. If one wanted to look for hope, the EPS broke a bit with continuity last night. Now, the look is not much better than before. However, the run-to-run trend and the actually 500 portrayal lifts the ridge out into Greenland. What that would do is allow a trough to reform in the East underneath it. In the LR, nothing much is gospel. However, if a model breaks once...not an unexpected blip. If it starts to waffle around, then changes are afoot which would be a good thing given its big ridge look from the past several days. As for the PV, it is tough to really know what it is going to do. Most winters it is a minor factor. With this being a Nino winter and warmth being transported poleward in a cyclical nature(not now), I wouldn't be surprised to see it get jostled more.

And another monster high w big storm showing up on the 18z GFS. Wonder if that finally works out at some point. While the GFS has whiffed of late on big highs, it does spot them before the Euro does in general.

Switched over now in Kingsport. Great sight!

It probably should go in banter...but that 1050 high at day 10 and that storm out of the GOM on the 12z GFS. LOL...that is just pretty much impressive. Wow. Man, I have seen a lot of storms on the LR, but that might be in the top 3 ever.

With it falling at night, that is also a plus for those of us trying to eek out an inch or two of snow in the eastern valley. Interesting for sure. Will also be interesting to see how the system at 144 evolves over the next few days.

If you look on models like the RGEM, NAM, and ARW....they all show several little ripples riding up that boundary. Very difficult to model. If the eastern valley scores on this, it will be one of those "micro-bursts"(man, no idea what to call those) moving from southwest to northeast. Again, we are probably talking the difference between one tenth of moisture. Not sure the models are precise enough for that...yet. One day they will likely be. So, I think the reason for the models "waffling" is we are talking about small amounts of precip making the difference between nothing and and inch or two of snow.

The 6z Euro has beefed up just a bit.

Kind of an interesting look at a144 that might have to be watched around 144 on both 0z Euro and 6z GFS. Due to the weekend storm pushing the cold boundary south, it sort of acts like a temporary block. Due to that, the storm on Monday right behind it was forced south on overnight runs. The frozen precip boundary is now along the TN/KY border for a bit, and then WAA kicks it out. The trend was well south from previous runs....needs to be watched because the trend is pushing that boundary south. Also, there is a HP over the top of that system. Looks like some energy will cut west of the Apps and mess-up the thermal profile...but that look overnight was new and might not be done. The GFS high on the 6z run even forced the low south of the Apps(barely). Need to keep an eye on that trend.

@nrgjeff, if this warm-up has duration...you need to sacrifice those lift tickets.

12z EPS implies that we "might"(famous last words) get some help from the Atlantic with AN heights showing up over Greenland. What is encouraging is that heights have lowered(not hugely) over the SE in response to that. Something to keep an eye on, and continues the odd trend of afternoon modeling being more conducive to winter than 0z.

Yeah, if the area of weak low pressure is going to hang that far back...might as well just slow down and come out as a Miller A. LOL. This time frame is the one where I thought there might have a shot at an overrunning even this week - just didn't pan out that way. That said, that HRRR map is very close to that, but the HP is just too weak. Now, let that energy hang back there about twelve more hours...nah, but fun to think about.

12z Euro is picking-up on some sleet/ZR in the higher elevations north of I-40 on Friday morning in SW VA(edit...sorry), NE TN and Plateau. Looks like it hangs on for several hours, especially in CAD prone valleys and western NC. Tnweathernut mentioned that high would not be easily moved if real. Looks like a good observation there. If the onset of rain is earlier, I wouldn't rule out some mischief in the valley. Not saying anything serious, but nuisance type stuff west of the Apps.

The 12z GEFS looks remarkably like the 0z EPS. Not that a cave means much in the LR...but that is pretty much that.

The Euro tends to really mess around with pieces of energy coming out of the southwest, and that messes up its solution in cases like these where the tail end of the front is lagging to the southwest. The GFS, which is usually more progressive, is more amped and thus has more accumulation. For west and middle TN, I think a blend of the two is probably a good idea. The faster this thing goes, the better it is for the eastern valley. IMHO, if all of this slows down, then the system just dissipates. Looks like a notable event for west and middle w/ the Plateau as well. I have slim hopes for NE TN. Just looks like the moisture zips out of here before meaningful cold arrives. I think west and middle might see 1-3" w the eastern valley seeing accums close to the Plaeau. Not sure this makes it to the eastern mountains though that seems counterintuitive.