Carvers Gap

The first NCAA football weekend of the year. This fall appears to be beginning at or below normal for temps. I am sure we will have some warmer temps as fall progresses, but what a great way to start it. Carry on

Looks like we may do this all over again in about 8-9 days if modeling is correct. Bout time for a fall thread!

Update, at 7:20AM we indeed tied the record low of 46F at TRI. The original mark was set in 1945. Setting record lows at that time of day isn't uncommon as it is usually coldest right before the sun rises.

Is this one of those winters where we might not have to erase massive AN temperature anomalies across the North American continent before it can get cold? It sure is starting to look like that if LR ext and seasonal modeling is correct.

Mt Leconte hit 38 this morning which is its coldest reading for Aug 27th since records have been kept there beginning in 1988.

Just missed the record low of 46. So far, looks like 48 will be the lowest that we drop at TRI. Update....The coldest WxUnderground station that I can find currently is 47 in KPT at the moment w/ TRI having risen a couple of degrees to 50. On a side note, bird migrations from the north have started early....

Downright chilly outside right now. It was kind of a shock given it is still August. I am gonna have to dig a jacket out of the closet in the morning.

Bout time for a Fall thread. It sure looks like the summer time pattern is starting to break down a bit early compared to recent years. Cold fronts could be getting further south than recent years if modeling is to be believed. And they are lined up one after another. I certainly don't think we have seen the last of the summer heat, but the sustained heat may well be over by Labor Day - ie weeks on end of high temps and humidity.

If you want a really good illustration of what happens when there is no gap in a mountain range, then the Bitterroot Valley is your huckleberry. Take some time and look at the annual snow totals for Hamilton and also at their winter temps. Then, look at Missoula's. Different worlds and only about 30mins apart. We nearly moved here, so I had done a lot of research about the valley. They used to grow apples in that valley. It is a true banana belt. The downlsope winds keep it warm for most of the winter. There are few ways for cold air masses to get south into the valley. Just of this area gets bitterly cold during winter. The eastern TN Valley is similar to this in many ways.

That also means the airport deals with downslope winds that Knoxville and western burbs don't see nearly as much.

I tend to lean towards the idea that AMO cycles flipped around 1990. We are due for it to reverse. As John noted last winter, there is some debate as to whether the AMO actually exists. I think the big change is that we finished a -AMO cycle during the late 1900s, and that greatly changed our weather in E TN. We also really need the -NAO in E TN to have decent shots at Nor'Easters. That is a different answer for the Plateau westward where the PDA/PNA ridge complex matters tremendously. There were some crazy strong El Nino's during the 90s. Right now we are in a pattern of La Ninas which I believe is driving the weather pattern here and placing the default NA trough over the Mountain West during many winters. Eventually, the pattern will change to something entirely different. La Nina is not great for the coast. It is weird, but TRI is kind of linked to DC's pattern. When it is snowy there, it is often snowy here. TRI generally does poorly in La Nada's and moderate to strong La Nina's. Strong El Ninos are torch city as well. We also have a wicked bad rain shadow here. Lately, downsloping over the eastern Foothills has been a problem. We are feast or famine up here. We generally do well w/ inland runners, sliders, NW flow, and a once in a decade setup where a low stalls/forms in the lee of the Apps. But trajectory of each system matters greatly. A slider with nearly perfect east-west trajectory is no good here. We need it to bend NE just a hair. The missing piece during recent winters are Alberta clippers. I believe the lack of clippers is probably directly correlated to the lowering snow totals. Joe Bastardi (who I like when he talks historical weather patterns) says that it snows where it wants to snow. During some winters, it just snows more here regardless of the pattern. He also notes there is a connection between late season cold and late hurricane action. One other JB note is that if a place has a rainy fall, that is generally where cold will try to setup. Those are fairly sound observations which have merit. Also as John notes, we generally hit big winters in cycles.

Oh, man. That isn't good. I have the same recollection of that year.

The PDO is not good. Extremes in, though, weather can wreck havoc. I remember some of those extremely -NAOs turned out to be terrible here. The NAO cycle right now appears to be trending towards more negative episode. I am gonna guess it fires early and holds off/on through January(beginning in late November). We are always fighting something. If it isn't the PDO, it is something else. However, during the last few winters we have found extreme cold making its way into the area despite a multitude of bad teleconnections. Until I see otherwise, I am riding the seasonal trend of cold early to mid winter. One of these days that extreme cold is gonna hit the atmospheric river over the TN Valley. I am gonna be here for that action Lord willing!!!!

Welcome aboard. I lived in Knoxville during all of the 70s. I had no idea how good that decade was at the time. During the 70s it often started snowing during late December and usually lasted into February quite consistently. Snow droughts weren't even really anything I thought about, though there were certainly some mild winters embedded during that decade. I also lived there during the 93 blizzard, the 93-94 winter, and 95-96 winter. The 90s did feature some snowless winters or nearly snowless in Knoxville. Those are easily the worst winters of my lifetime, but again, with some great winters embedded. Knoxville has done really well recently(2020s to clarify), even better than TRI during many winters. I do think that notch along the Plateau funnels precip into the Knoxville area - someone (maybe @TellicoWx) had a great post last winter about it. At TRI, we have no such relief...just a solid Plateau wall to our West. At first I was a bit skeptical that the Knoxville notch helped. But when out West, you can see where openings in the mountain ranges (which lie west to east) have higher snow totals. For example, Alpine(WY) is much snowier than Jackson(WY), but Alpine is at a lower elevation. However, Alpine sits right in one of those notches if you look on Google Earth. Places in Star Valley to the south have less say in Afton. Afton is at higher elevation - but no opening in the mountain for snow to reach it easily. So, long story short. I think Knoxville does really well during certain NW flow events(almost wnw flow events), during snow storms where the fetch is from the SE(but limited warm nose), and they do incredibly well with sliders. Sliders seem to be our best snow makers these days, and that would also explain TRI getting less snow during recent winters. I would say "for now" that 4-6" is about right for Knoxville, BUT recent trends definitely have Knoxville trending better. I would guess there are places in the Knoxville which are averaging 10+" during good winters recently. At one point during the 2010s and 2000s, I can remember on this forum where Knoxville would get very little compared to TRI. Recently, Knoxville has had two really big snows. I do think the sliders in conjunction w/ that notch where I-40 comes into town is the big contributor. Even during those 197-s winters as a kid, I knew the best snows usually went from Memphis to Knoxville. Still true today. I also think the 2020s and late 2010s cold shots, though short lived, have produced an environment where Knoxville kind of is in the sweet spot. Gulf moisture interact w/ the cold air from the North at about Knoxville's latitude. South of that, no luck. North of that, too cold. Again 4-6" is probably right as a generality, but I wouldn't be surprised for Knoxville to surpass that average during some(not all) of the upcoming winters if trends persist. I think this winter has a chance to be good for TYS. Here is a TRI note....The early 2000s didn't have a tone of snow here. As this century has progressed, small snows have become more frequent as have some the frequency of short-lived, brutal cold snaps. Big snows have been less. Why? I suspect moderate to strong La Ninas are the likely cause along w the aforementioned PDO by met85. We have had a load of La Ninas since 2016 or so. In NE TN we really need a weak ENSO state but not neutral and definitely not moderate to strong. As John notes, that is less a player as you head west and has less correlation from the Plateau westward. Though, I could make a pretty good case that middle and western Tenn have done decently well w/ the La Nina pattern. Interestingly, east Knoxville and the Foothills are probably is in the same boat as TRI. TYS during good winters: 8-10" (frequency of that about 1 out of every 2-3 years currently) w/ higher lollipops depending on local TYS during lousy winters 2-4" It just seems to want to snow in Knoxville of late. That is weird to say from a scientific standpoint, bit it is kinda true.

I have been sucked-in by La Nada before which is what the SSTs kind of look like. La Nada often looks great at the start, but lots and lots of swings and misses. That said, I have a hard time seeing lots of. misses w/ the Dec-Jan setup as depicted on this month's seasonal Euro. That is about as good as it gets. The fly in the ointment would be cold source and a ridge bellying underneath across the South. The Great Lakes region looks primed for cold. Can it get south of the Ohio River? We will see. I do agree the QBO should be good for this winter - such an odd metric to be so accurate. Honestly, it is a weak Nina in the eastern Pac and a weak Nino in the western Pac -> maybe that is the ticket which is the best of both worlds. That warmer western Pac might be enough to get convection into phase 8-1 during mid winter. It may well be that we see the NAO fire again as recent winters have seen it much more active in a good way. John might have better information about Nada's w his personal records in conjunction w/ the QBO. His data set is the only data set I truly trust for this region.