Carvers Gap

That isn't a whole lot different than the 18z RGEM. That is a pretty aggressive forecast.

@Met1985, did you see the 18z RGEM. How much rain falls in W NC on that run!? @Windspeedthe 18z NAM looked a little more tame. The RGEM is "turn out the lights" bad for many areas in the mountains.

The system two weeks ago was handled very poorly by modeling. Just kind of saying that as a caveat, the 12z NAM would be a drought buster.

The 18z GFS paints a bleak picture for western NC with this next tropical system. With the upslope, that would have the potential for significant flooding IMHO. Downslope would protect most of E TN with the exception being SE TN.

It does look like the summer surface pattern is about to break down bigly. The tropics look active as we are pretty close to that double dip(two tropical maximums) common during La Nina. I would bet that when the last of the tropical systems scoot out(mid-late October), I bet it turns pretty cold.

Probably a big ol' tropical system right under that.

Yeah, as SOON as I talk about it, it goes away.

I do want to clarify one thing. My high school drafting teacher was the best teacher I had in high school. It was my favorite class. She was a tough grader, but that kind of made it fun. Had to work for a good grade. Anyway, let's get some fall arriving soon, @John1122. Bring it!

Some nice cold fronts are starting to show up on the control runs of ensembles in the LR.

It has been awesome today. Light rain, drizzle, and a breeze. The leaves, as John noted, are starting change. We still have some heat to navigate, but today has been a nice touch of fall.

I see that we have more reactions to choose from. I think we need to really have a "97" reaction, because my high school drafting teacher would only give us a 97. She said that great drafting was never really perfect - awesome teacher by the way. We also have an "x" and a "crap" reaction. I predict that we see a lot of those during Jan and Feb, definitely March. Or if someone goes full Boomer Sooner on us next weekend....we could get some early use of those. So if you need to test some of those out, this is the post to use. LOL!

And man, good to have you posting again!

I think it sprinkled here! LOL.

The GFS total whiffed on this. Bust city. Several models were further west, and they were correct. But this thing in reality was way west of most guidance from a few days ago. Lots of schedules were changed due to this, but not sure forecasters could have done much. It is a really good example of an outlier being wrong, but didn't get tossed soon enough. It had the trend until it didn't.

The GFS really missed with Francine. It was too far to the east. I think the actual storm is in the Ozarks now!

Some HL blocking is starting to show up at the weeklies 6-7 week range. There are understandably a wide range of options on the table ranging from a GOA low to a very -AO to a strong EPO ridge. It looks like what shapes our pattern will be upstream blocking vs Atlantic in nature(at least for now). The Euro Weeklies control brings winter to much of the continent by late October. The snow pack in Canada w/ that scenario would build quickly. Alas, it is shoulder season, but this fits w/ Nina climatology. Heat relaxes, fall advances, and then one more shot of AN air during early-mid October. Then the bottom falls out. These are the opening moves of winter on the ext LR models. Just food for thought and nothing overly serious at this point. I am not even posting thumbnails. Huge grains of salt.

Some ares were approaching record lows agains(jus a couple of weeks ago was similar) this morning. LR ext(weeklies) models have cooled again. There is a pretty massive ebb and flow on modeling right now. I am sure it is a combination of being shoulder season and also this tropical system shaking things up. My guess is that there are going to be some wild swings in reality.

Yeah, the shoulder season flip/flop got me for sure. Looks pretty warm in the LR ext now. When in doubt, climatology is gonna win most times. I think La Nina is getting stronger, and extended summer fits that. I would expect a sharp flip to cold by later Oct or early Nov....maybe even winter time cold. The tropical system next weekend may also be a problem for modeling....that could shake things up.

And BTW, I don't think that we haven't seen the last of summer. I should never, ever have posted the above. LR ext models somewhat flipped the day after I posted that. Still, it is shoulder season, and really anything can happened as modeling is often very wrong.

I posted a "just for fun" 2024-2025 winter outlook. Just scroll down on the TN forum page. Feel free to add your thoughts and/or make your own forecast. Either is fine by me.

Well, we are just twelve weeks out from December, so I thought I would start a spec thread... I actually like these ideas in the article below: https://www.severe-weather.eu/long-range-2/winter-2024-2025-first-snowfall-predictions-united-states-canada-europe-fa/ I tend to think that our best shots at winter will be late November to late December, and then it gets warm and maybe stays warm. That said, as others have noted in the main discussion thread for fall, the strength of this La Nina is important. The IO is important. The PDO is important. The MJO is very important. PDO -> The September Cansips has the PDO staying solidly negative for the winter, and not really even coming up for air at that. MJO -> This will tend to favor warm phases as phase 8 will be cooler than normal and that limits convection there. IO -> Off the coast of Eastern Africa, there is warm water depicted. That would favor phases 1-2 of the MJO. It also favors warmer than normal water over the Maritime Continent which favors 4-6. 500 Heights over NA -> November a ridge is shown to be out West. It transitions eastward as December progresses, and then parks itself over eastern NA for Jan and Feb - monster SER of sorts. Maybe by April it relents. The NAO might be negative for the first 1/3 of winter before returning to a net positive state. It would not surprise me to see the pattern relax by April, and we see chances for snow in early April (especially the mountains). SSTs -> The La Nina on Cansips appears to fade significantly by February. By next summer, we might be seeing Nino conditions for the western 3/4 of the Pacific. We have talked about gradient. @Typhoon Tiphas mentioned gradient many times(I think I have the correct poster). That means the delta (difference) between the La Nina and the waters around it matters. The steeper that gradient, the more of a stimulus we get. El Nino was kind of a washed out gradient last winter, and we got washed out results on the EC. From the recent climate.gov ENSO blog, "Said more simply, it’s not just how much warmer or colder than average that part of the tropical Pacific is that jumbles up the tropical atmosphere, it’s the difference in warming or cooling compared the rest of the Pacific. And that’s where the relative ONI comes in! So where do things stand? The regular ONI for May-July was +0.2°C. But the relative ONI was already down to -0.4°C. That means there could be a scenario later this year where the ONI is not yet below -0.5°C, but the relative ONI already is, and the atmosphere might start reflecting La Niña-like impacts. Doesn’t that seem like a pain to communicate? " To me, since the Pacific basin is warmer than normal, La Nina might well have a threshold warmer than what we saw maybe 30 years ago. That means that what we see as a weak La Nina might actually be a bit stronger than we think. So, the weak La Nina forecast below might well be a bit stronger given that La Ninas might have increasingly warmer SSTs. Overall Forecast: I do think we see some crazy cold air masses at some point. I do think the Mountain West does really, really well in terms of snow and cold. In fact, the higher elevations there are already getting snow. Their winter has already started above 8,000'!!! I do think that middle and western portions of our forum will see a colder and snowier winter. But beware, if this truly turns out to be a weak La Nina....all bets(and I mean all bets) are off the table. Weak La Nina's in E TN can often be bitterly cold. So, instead of doing a monthly J-F forecast, I am going to simply put out a general forecast. One, well-placed cold shot during Jan-Feb could really skew things. During 2017-18 we had a crazy cold shot that straddled late December to January. It didn't snow much but was crazy cold. We were below freezing at TRI for seven straight days! The monthly climate data doesn't really show that cold shot as it straddled the end of one month and the beginning of another. That winter was also a weak La Nina. I am liking that analog year 2017-2018. If we had any precip in that pattern, we would have been buried. As it was, it simply froze things solid. December was -0.8F . Jan was -4.5F. Feb was +9.4 F. March was -2.1F. April was -4.1 F. Maybe we had a strat split late that winter??? I am going to go ahead and add these. And I am far, far deeper into this than intended...Sorry, this is kind of a "stream of thought" post, and maybe not as scientific as it should be. I also want to add 16-17 into the mix at it was a first year La Nina and should be weighted equally or more to 17-18. But here is why I am far less confident this winter. See the 94-95 moderate Nino listed in the graphic at the very bottom of this post. This past winter reminded me of that type of winter - blah and not a lot of chances. Now, what came after 94-95? The winter that shall not be named, because I just won't invoke a winter that is a benchmark winter of my lifetime, and it was true winter. It was a weak La Nina following a moderate El Nino. It is also a winter that maybe doesn't fit the current warm basin look of the Pac which is why I haven't used it. That said, it might deserve some weight though I haven't given it any. Just beware. So, for now, I like the 16-17, 17-18 blend of weak La Nina winters. December looks chilly. Jan is a tossup, but leans warm. Feb looks warm. I did break down the 16-17 winter by month as well as 17-18. I also provided a blend of the two which I tend to like better, and is probably pretty close to my thinking. In addition, the 16-17/17-18 analog blends might be of better use as they are recent analogs, and not almost 30 years old. Plus, those two analogs came from a weak El Nino which I think is a better fit. Notice that the March blend is not overly warm on the EC. I do think maybe some late season chances exist north of I-40, especially in E TN and the southern Apps. ***The following would be my best guess for winter temps.*** Refer to the article at the very top of the page for snowfall anomalies. Those looked about right. Reference for ENSO graphic list: https://ggweather.com/enso/oni.htm And if you made it this far, thank you for reading this! I intended to make a short post, but ended up just saying, "Screw it," and wrote a long post. LOL. I normally don't like long seasonal forecasts, and really, those long posts end up being very wrong much of the time. I really think seasonal forecasting often involves false correlations, and I am sure my post is guilty of some of that. In other words, sometimes my seasonal forecasts might "appear" to be correct, but often it is just blind luck that they even got close. In other words it is like saying TN is going to win a ballgame because of Nico, but really they win because of great defensive line play. They won, but not really my line of thinking. So, have some fun with this, but don't take it as the gospel. This is just for fun. Feel free to post your winter ideas in this thread. And this thread is not meant to be the December 2024 winter thread. That will have its own thread. This is merely a speculation thread, and won't be rolled into a winter thread. If this verifies, we could see some cold college football playoff games during December....

I think the worst of summer is behind us. There might be one last warm shot during the second week of Sept, and then again by mid-October. But the LR ext models are signaling a fairly BN temp pattern for Fall. I wouldn't be surprised to see an Oct warm-up as that fits the tropical double dip that we see then.

Not that drawing much from late August analogs means much, but that analog package yesterday featured about 2/3 of the years having a very cold month or two. Wild swings. Blend those three sets together, and that is a respectable winter.

Interesting about the flooding which preceded a doozy of a winter. There is a line of thinking that normal to AN rainfall during fall is a signal for a trough in that area. That might be something to watch for. Right now, September looks rainy but not excessive. Oct could be pretty dry...just looking at ext runs. That said, one tropical system could change all of that one way or the other.