Carvers Gap

As for severe wx, bring me some thunder in the mountains....

Also, it should be noted(heard this from JB) that we are actually dealing with two SSWs. One is going on at present and the other will begin in the d8-15 time frame...that is the one that is really going to heat things up. Looks to me like the PV gets stretched a bit at 10mb late in the GEFS run. As HM notes, would be very unwise to "swing for the fences" (with a call for cold or warm) right now with so much uncertainty at high latitudes. Also note that a brief but near record ridge in the East often precedes a PV split. Need to be on the lookout for that. That feature has preceded the last two PV splits. That much warm air surging into the Arctic is gonna leave a mark. Also, I think we have had PV splits at the tropospheric levels that were not "top down" events which were results of SSWs. Double check that...but I am pretty sure sometimes the PV can split without the stratosphere forcing it. Right now, IMHO, we are still about 15-25 days from really weakening the PV and maybe 10-15 days after that the tropospheric PV gets forced off its spot. So if we use the six week rule(see John's post above), that would actually fit the timing for a new pattern. Maybe the seeds for the pattern are being planted now. Also, for future reference, I don't think anyone is calling for major cold over E TN at this point. Just discussion SSW events. So, if one of us comes back and reads this thread later....just kicking stuff around, but not calling for an Arctic outbreak.

Great winters can definitely happen due to SSWs and they can also ruin good patterns IMHO. Notable SSW events that really enhanced and helped great winters to occur were Jan 1977, Jan 1985, and Jan 2009. IMHO, last year's SSW did actually propagate correctly to tropospheric levels. That SSW split into multiple vortices. Incredible cold and blocking did result as a trough tucked itself over the northern Rockies for months. Island Park, Idaho, set multiple snow records. As I had mentioned before, I was in MT/WY/ID during late March and early April of this year. In West Yellowstone, the snow was stacked up to second floor windows. They did not have much winter prior to the split of the PV which was a result of the SSW. February was epic. Folks couldn't even get to the river's edge on the Madison near 3$ Bridge without skis. Then, they had to find an entry point to the water. Some drifts were 10-12' high at the river's edge. For us, it screwed-up a return to a decent pattern. Remember how November was cold and that has a reasonable correlation to a cold winter. Well, the pattern changed on time to a warmer pattern last December after a massive head-fake to cold(multiple head fakes seem to be common during SSW events). The SSW lasted for much of the second half of December, and the PV split. The West, which hadn't had much winter at all, then had winter on steroids that lasted well into late June. As a note, warming at 10mb, 30mb, and 50mb can occur much earlier than the actual PV split event at the troposphere. There is great debate (on whether an SSW that does not result in a PV split at the troposphere) can result in major changes in weather at the surface. I am in the camp that the warming itself is a great indicator of blocking. What is the great unknown is where the blocking actually develops. The SSW during later winter and spring of 2018 resulted in a very cold spring with plenty of frozen precip and cold during March and early April. It took some time for the troposphere to react to that event. Last winter, the atmosphere reacted well before the event even occurred. So another variable is lag time. Those two variables, lag time in affecting the surface and where the blocking sets up, create total havoc in modeling. We don't have enough analogs to really know how that occurs. Things like ENSO, solar, and QBO also have to factored into SSW events...and that creates incredibly small analog packages. As for the great winters of '77, '85, and '09. They all had them. Again, it is important to remember that SSW events usually begin well before the PV splits. Seems like '09 had warming early in December. The winter of '85 was a pretty ho-hum winter until mid January. I don't remember much in NE TN that was overlay notable prior to that split. The second half of that month and early February would be the some of the worst winter weather(interpret "worst" act cold and snowy) that I have ever experienced. Spent many sub-zero nights in a crawl space trying to fix broken pipes with my dad. I remember how tough it was to actually get the frozen water out of the pipe so it wouldn't melt later and ruin the solder joint for the new pipe. The winter of '85 reminds me very much of what the northern Rockies experienced last winter...very average winter that suddenly flipped to extreme cold and snow. I don't remember much about '77, just that it was really snowy. It is of course, the benchmark of what many will say is winter. In conclusion, SSWs don't always result in PV splits. However, IMHO they can still impact high latitude blocking, but not always. During an SSW look for abnormally strong spikes in teleconnection indices. Big unknowns about SSWS and ensuing PV splits are where the blocking sets up and how much of a lag(time from SSW to PV split at high altitude to propagating to troposphere) there is. Those two variables IMHO can create total havoc in modeling. A small rule of thumb that I use is that when bitterly cold air is dropped into NA, weather models go haywire. I have also noticed that SSWs can cause models to flip-flop at the last minute as they did last winter. Many great winters did not have SSW events, but the many of the worst ones have them. Also, someone check and see if 14-15 had an SSW - that winter is probably the snowiest winter that we have had since 95-96(not an SSW) in Kingsport. Great discussion, everyone, and Happy Thanksgiving!

A childhood friend of mine sequences the DNA at the CDC for the flu vaccine. Crazy, huh? Some years they miss pretty badly. Some years are really good. As for basketball, going to take some lumps with the new team in Knoxville this year. With the #4 recruiting class in the country, help is on the way next year though. Hopefully, we can still grab an NCAA tourney spot this year.

I do think we maintain the base pattern as a trough in the East and ridge in the West. That doesn't mean we won't have the opposite at times this winter. That doesn't always mean cold either. Some troughs are full of Pacific air, and it just rains. Also, it is pretty rare to have a wall-to-wall trough in the East. Honestly, I don't worry too much about the pattern in early December. We just don't get a ton of snow at this time of year...and I say that pretty much every year. Early December is not a snowy time IMBY regarding climatology. Best time for snow here is January though the first two weeks of February..and maybe throw in the last week of December. So, we really only have a reliable window of six weeks each season which is better than some regions and worse than others. But let's see where this SSW takes us and where the IOD(which has fired up) takes us. The IOD may prompt the MJO to take a tour through its warm phases which it has been reluctant to do. The MJO really does not want to go into phases 4-6 during Nino winters, but one tour won't break us. The SSW might actually mute the MJO(or even be caused by what is causing the MJO to remain active). Like I said, plenty of plates to be juggled. I think a warm-up is very plausible as I noted earlier in the thread. That said, I think we return to the base trough.

I think last winter was a head scratcher because many models and accurate seasonal forecasters(is there such a thing?) had the East as cold. That is not the case this winter. Isotherm actually has nationwide warmth. The Euro seasonal is not BN over the East. El Nino winters are not known for extreme cold...just their storminess. There were people last winter who noted in this forum that many seasonal forecasts were too cold. (My current seasonal ideas are in the summer thread and were posted back in June. No changes there.) Regarding the strat split last winter, it was the real deal and it wrecked havoc. It did produce extreme cold and snow. It just went West. IMHO, the West would not have had a great winter without it. As Mr. Kevin noted, not all strat splits propagate into the troposphere. The last two have. SSWs can have significant and unpredictable impacts on the hemispheric circulation pattern. Do I think lightning strikes twice and hits the West again with SSW, steroid-type cold? Nope, but it's not like the northern Rockies are known for warm weather anyway. What they are getting right now is very much based in Nino climatology which is a cold star to winter. They did not have a cold and snowy start to winter last year. It came in February. I noted the West would likely have a quick start in my seasonal ideas back in June in the summer thread. However, the NW precip has been below normal this fall I think...until this past week. That is a Nino signature as well. It is definitely plausible that the EPO ridge could allow for a trough to tuck into the Rockies at times. Everyone's burning question is will this winter get cold and we have things to track? I think so, but I don't get to write the script either. Given our latitude, we have good winters and bad winters depending on your point of view. So, the bad winter trend will almost assuredly change. At some point, it will get cold again. Jury is still out on this upcoming December. One could make a good argument either way. In my thinking regarding December, I would likely weight AN chances a bit heavier, but not by much. The ensembles last year were cold heading into December and then flipped warm. The ensembles right now are all over the place. The SSW that is occurring is earlier compared to last winter which is not uncommon(to the best of my understanding) during low solar and El Nino winters. Last year, it was in late December with the split in January. Right now, I can't find any modeling that shows an actual split. One would think that all of that heat is going to really weaken the PV though. A weakened PV means that it will likely meander to lower latitudes on one of the major continents or both. If that PV was wound-up tight...I would be super concerned about a warm winter. And it is also important to remember, Decembers are truly often warm during El Nino winters..but not all. Heck, I am not even convinced December will actually be warm, but it likely will be based on climatology. The 0z EPS( @tnweathernutnoted this above...I was typing this as he posted...ninja!) shows banana type ridging over the top late in its run which, if it verifies, would mean another period of cold sometime during week two or three of December. Modeling a few days ago was quite warm, and has backed off considerably. Until this SSW is worked out...tough to really know where this heads. One nifty analog out there is 14-15 which had a warm December and colder January and February. The big EPO ridge on the past few runs of the EPS would deliver very cold air into NA. I do like John's comment that a new six week pattern would deliver a new pattern it January. I will say, I am not convinced that what we are seeing(ridge in the East) is not a relaxation to the current pattern OR that the December pattern is even worked-out yet due to the SSW chaos. I think modeling right now is prone to some wild flips due to the SSW situation and the active IOD...lots of plates being juggled right now. Lastly, as someone who likes to make predictions/forecasts/present ideas...better have a short memory just like a defensive back. There are going to be times that you get burned and burned badly were everyone is gonna see it. I called for a warm November last year, and busted. Just have to go back out there and do what you know to do. And besides, if we were always right...would it be any fun anyway? And have a great Thanksgiving. Life is short. Enjoy these temps. I have almost daily been thankful it is not 95 every day! I hope I never see that September pattern again.

Biggest thing to watch is the 10mb temp anomaly forecast. Tough to know how if this will reach the troposphere or not...I think it eventually will, but that is only my opinion. I think when the teleconnection indices get those extreme looks...very likely that the SSW is having some impact at 500mb. We actually have had some warming this week I think. It is possible that the models are actually picking up on that event in the LR and that the big warming event beginning in a few days is unlikely to be having an impact on surface weather yet. IMHO, an SSW is like throwing one of those rubber dime store balls in the living room. It is going to be spectacular. It is going to likely break something that cannot be fixed. And there are gonna be some happy folks, but there are gonna be some mad folks. About the only think one can predict is that once it is released...it is going to have to take some time to finally run its course as all of that potential energy turns into kinetic energy.

Cutters right now. Maybe as we get into winter the cold presses. Looks like a base pattern of a western ridge and eastern trough. Very little help in the Atlantic. Looks a lot like the pattern from 14-15 which depended on the northern stream for winter weather. That 12z EPS ridge today was pretty massive. Thing is about the Weeklies is it is really tough to tell about amplitude. They have really missed on that aspect. The Weeklies have looked pretty bad for most of fall...might be the first time I have seen them workable...they whiffed on November. Pretty rare to get early December snow here...last year was the earliest big snow we've had since I have been alive. If we score a storm with an inch or two of snow...would be a bonus. And honestly, with the SSW on fire right now...really doubt that any model has anything but broad solutions correct.

Looks like Sugar Mountain is open for business. Slopes look decent considering it is only November 25th. That is a testament to the cold November that we are having. Good for them...last year was not a great season. Getting open by Thanksgiving is always a good think for the hills in Boone-Banner Elk. If you need a snow fix...you can watch some of the night skiing session this evening. http://www.skisugar.com/cams/

Realistic run of the Weeklies(Euro) I thought. Pretty representative of the current pattern. Periods of cold. Couple of warm weeks during Christmas and right after with a return to seasonal right at the end. Keeps pushing back the warmer pattern.

12 EPS doubling down on a very stout EPO/PNA ridge out west combined with a ridge in the Atlantic during the d10-15 time frame. I would think that is setting the stage for some serious cold to swing into the pattern. That look seems to be the SSW type block that is just crazy. At one point the block is almost into areas well above the Arctic Circle. The Aleutian low is impressive as well.

Nice PNA pops on the long range 12z GEFS. Probably would depend on NW energy for winter events, but not a bad pattern for December. And definitely better than what is was cooking-up for the past few days.

And hey, we even have a d10 storm on the 6z GFS. It progressive bias makes that unlikely, but it does phase that system. Maybe something to keep an eye on is the upslope event still being advertised for next Monday. That has been a fairly consistent feature for a few days now. You know if your area is favorable for that, but wouldn't surprise me for northwest facing slopes above 2,500'' to see measurable snowfall early next week with that. If that storm cuts and is as powerful as advertised....going to drive some cold air with latent moisture in it. Wouldn't be surprised to see areas on the Plateau, places like Max Patch, Roan Mt, and areas of western NC receive some snow from that. Thankfully we are not in a dry pattern. If there was one concern that I had during early-mid fall is that we were in a dry pattern. Keep the current pattern, and we should have our chances at some point just due to precip being in the pattern. Think it was 2017 that had that crazy cold shot in December where we had exceptional cold but no precip as the mega-EPO ridge was so tall that it had no precip.

Check that...now the 6z GEFS has joined the EPS in continuing the block over Greenland along with a trough east of Hawaii in the LR. Way out there, but good to see a continuation of the evening runs yesterday with the exception of the 0z GEFS. The 0z GEPS(edit) also looks workable. Maybe that Greenland block is doing some work. Might it also be that modeling is beginning to get a handle on the SSW event. I would definitely keep one eye over my shoulder with this...probably going to be a lot of movement. Even though I wave December warm...part of my gut thinks this December is going to buck some trends. As someone noted, the West is due for a warmer winter...and the East is due a cold one. Sometimes the law of averages comes into play if that makes sense.

The 0z EPS and GEFS have flipped in opposition to each other and the EPS is in eastern trough camp. Now, the EPS has been pretty awful of late. However, it is getting to be the time of year that we want it in our camp. As Jeff mentioned, once we get into winter proper, the LR models begin to settle down a bit. The EPS has a very workable pattern as it rolls the ridge through and keeps neutral to AN heights in the Davis Straights regions. We will see if it holds. The EPS has been reasonably steady with that look for a few runs. GEFS is bouncing around. It is really easy to get fooled at this time of year. Last year modeling(edit) looked cold - went warm. This year, the look has been cold...and now warm...and now one model back to cold. Going to take a few days to work this out I think.

Strong work. I hope it is short- lived. Always seems like strong blocking events decay slowly...unless of course it is blocking favoring the East coast. LOL.

Yeah, pretty significant warming at 10mb being modeled. What we don't know and what models don't model well...is where the blocking sets up after the SSW event. Last year, when the SSW was being signaled in mid-lat December(actually split in early Jan) seems like much of the modeling signaled a cold mid-Jan into Feb. Obviously, the cold unexpectedly dumped west(unexpected relative to it being shown to go elsewhere from about 2-3 weeks out...If I remember correctly). I definitely buy the SSW throwing the indices into extremes. And I also think there will be some surprises(relative to what we are seeing and not seeing in modeling right now). The 12z EPS didn't look to bad BTW. 18z GEFS looks similar. Seems like the morning model suites have been warm and afternoon/evening suites have been cooler.

And sure enough the 18z GEFS goes stone cold in the LR. Seriously, it is like washing your car thinking it is not going to rain.

Pretty strong warm signal for mid-December with that CPC forecast for the AO...the MA forum has been discussing it today. So, I went and looked for myself. If that verifies...going to be some very warm air east of the Rockies somewhere. But hey, maybe this is our year to buck the indices. We will see. My guess is the SSW situation is triggering some crazy stuff at high latitudes. Everything(Modeling, indices, etc) went pretty wonky during the last two events. Not sure this one leads to a split...but it might as the PV looks fairly elongated on the 12z Euro d10 map at 10mb. I think we have a good window during that first week of December. Last year, basically same deal occurred. Great window and the models flipped almost concurrently to a less than favorable pattern towards the end of December. Only good thing about that...I don't think lightning will strike twice in the same place. Really don't want to see the AO go that positive...that would be a long term problem I think. I think Bob Chill in the MA forum compared it to an AK vortex. Don't want to see a big +AO or an AK vortex as the break down very slow many times. Again, a warm December is very plausible given the cold pattern that preceded it and that it is a Nino-ish ENSO set-up. Fingers crossed for Jan/Feb 2020 as last year it just went warm and never looked back. Hopefully, many of the models are on "mayhem mode" as this SSW and seasonal transition is probably making a mess of things. That said, we can definitely see into early winter now on modeling...not sure I am a fan at this point of what I see for early winter. But it is still early.

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GFS(12z and 18z) and CMC(12z) are both hinting at a fairly strong upslope event beginning late Thanksgiving Weekend. 12z Euro is not too far off from that...looks a bit too wound up. Strong NW flow coming in nearly perpendicular to the mountains.

UTM at UK..Flipping channels and saw a driving drizzle(no idea what else to call it). Winds are gusting to 17mph. Temps is 44. WC is 37 per TV(seems like that would be colder). Evidently people are trying to get int the bathrooms just to warm-up. Looks cold, man.

Looks like a pretty good squall line around Knoxville. Any reports from folks under that line?

The Tennessee subform rocking impressive metaphors this week. Pretty sure I will be laughing about Jeff's quote (about adventure books and the GFS) for a long time. And I will also be using the phrase in that tweet again - 99 cent bin superstorm.

That is pretty craptastic, but glad you are back! Hopefully this week will be smoother. I had a similar week about two weeks ago.