Carvers Gap

The GFS and CMC are MUCH colder for next Saturday, and have a crazy hybrid system embedded. Let's see if that flip to cold holds at 12z. Major changes overnight on those two models. Euro isn't buying it quite yet.

Strong cold signal showing up on the 12z GEFS after mid-month. The Euro Weeklies had this to some extent on Monday.

The GFS is really banging the drum at 6z. Cosgrove on Facebook is mentioning a cold weather intrusion. There Holy Grail of November wx (for me) is a hybrid tropical system that gets entrained in legit cold front. Outside chance of that right now. That said, the GFS has been in error w/ that look at LR for about 2-3 weeks. However, that looks is now at d8-10. We know the euro struggles during shoulder season. At the very least, the GFS is now leaning towards a cold shot late next weekend. Weather is just a wee bit more interesting than it was a few days ago...

Now, let me explain. There is a tropical system approaching the coast around d8-10. If it gets caught in a front racing eastward, we get the KOD(kiss of death) early season winter storm that models have been trying to cook-up for weeks. Something to keep an eye on...but the 18z GFS is almost exactly how that might occur.

The 18z GFS is flirting with greatness.

CFS v2 18z is seeing a similar trough amplification after Nov10th. Is that the opening shot for winter? Maybe. Long way to go. I really think one good amplification would pop the ridge in the West and put the trough in the East. Ensembles aren't biting yet. That said, and I thought about this yesterday, shoulder season LR modeling is full of false alarms(both warm cold) during past years.

The 18z GFS is the way to a good pattern. Almost need a tropical system to jet up the coast and buckle the jet along the EC.

Yeah, seems like something similar might be on the table....

Just glancing at some super LR modeling, looks this indeed(the warmer weather) is a new pattern which (if you know me) I use a general duration rule of about 4-6 weeks(usually 6 weeks is my rule of thumb). Since this will begin around Nov 1, that would put the next pattern change around mid-December. Now, a pattern change could just be another warm pattern of a new variety OR a pattern which is only slightly AN OR one which is well BN. That would mean the heart of winter has a chance to be cold (mid-Dec to end of Jan) - I lean towards that. Only drawback is one cold spell during winter instead of two. Bookends of DJF would be likely warm. It is what it is. I would be difficult to find a more hostile Pacific in the LR. The only way I see us having a cold winter is if the blocking occurs in the NAO region. Though, I will ride with the idea that we will see 1-2 extreme cold shots, especially Plateau west, as that fits Nina climatology. Hopes for an early start to winter are dimming.

FTR, I do think we see a sharp switch to cold sometime in early to mid December to a cold pattern. I think this warm wx is a a 4-6 week pattern which is just beginning. Maybe the one positive to warm wx during November is that it may help with having colder wx over the holidays.

Nah....I take full credit for the massive warm flip in modeling. Just dig back a few posts and you will see the culprit post around Oct 10th. Hot take on my part!!!

We need a tropical/hybrid to break-up a potentially monotonous pattern showing for early-mid November. Big ridge building on most modeling, and might be quite tough to move once in place. My guess is that the pattern will flip on a dime as most Nina patterns flip quite quickly to winter. Anyway, summer-ish(early fall) like pattern showing for the first part of November. The pattern looks a lot like a standing wave(ridge) over the East. It gets knocked down but keeps most of the nation east of the Mississippi 5-20+ degrees above normal. The Euro control has some areas 30+ AN. I thought we might have dodged extended summer which is common with La Nina. This will be "extended summer", but without the ultra hot temps. We have had a nice Fall so far....warmer temps are back and are going to make an attempt to hang on. Bigger issue is the quickly developing drought in conjunction with warmer-temps.

@John1122, the 12z GFS has it yet again (different variation). That is a pretty potent set-up if it grabs energy out of the GOM at this time of the year. BTW, the GFS did pretty well with today's cold/snow at very LR.

Yep, indeed the GFS has had it between hour 330-348. As maligned as the model is sometimes(and rightfully so), it has an uncanny ability to catch some major events at wicked long ranges. Strat splits come to mind.

Fits our climatology fairly well. Seems like we have seen our first snow storm around halloween about 1/5 years. When I was a kid in Knoxville, that was unheard of. However, of late, early season storms have not been uncommon for the mountains. The GFS has been sniffing something out during that time frame for several days. It will be interesting to see if other modeling picks it up as it sits at 240h right now. I bet if we look back, the GFS might have had this from the word "go."

Last night's Weeklies and 12z GEFS seem to signal just a temporary crappy Pacific set-up (TCPSu) vs (PCPSu...permanently crappy Pacific).

Very familiar pattern on the LR GFS w/ a Hudson Bay Block but crappy Pacific.

Looks like a temporary trough amplification in the East, a transient(maybe 5-10 ridge out West), and then a more permanent trough in the East for November if the "shoulder season" Euro Weeklies are accurate. You all know the rules on that. That pattern would bring early snows to the mountains and snow showers to the valleys.

Yeah, @John1122 may have some additional analogs as well along that line. Every once in a while, winter hits and holds during this type of ENSO pattern.

Yeah, that fits with what many have been saying here for a bit.

Kind of crazy, but there is a winter wx set-up in the day 7-10 time frame. Climatology says otherwise, but still.....

Gonna have to read my comment today in the Winter Spec Thread for this to make sense. The hybrid coastal/inland snow set-up is clearly apparent on the 18z GFS late. No idea if that verifies, but the potential is there. It is not unprecedented. I remember @tnweathernuthaving to trudge through snow to get to the South Carolina game one year....snow in South Carolina!!!!

12z EPS looks solidly chill. And yeah, wouldn't be the first time to use up a great pattern in October. Seems to be a trend during the past decade or so. I have seen way more early season snow/cold than normal of late. General rule -> Tropical hybrid system which produces inland snow wrecks havoc on early winter projected patterns.

We were in Clarksville Saturday more middle school state XC championships. Pretty amazing how dry it is there.

Some signs that a fairly stout(but is it long lasting?) PNA ridge is about to form with and ensuing downstream eastern trough later this month. Still a bit early for the early winter La Nina climatology to kick-in, so we'll see. It is showing up on ensembles pretty consistently and starting to show somewhat sporadically on operational runs. But it looks "not warm." Trough is also in the Aleutians which tele connects well to cold here.