Carvers Gap

I like watching the daily run of the CFSv2 seasonal. I generally watch trends. It does bounce a round quite a bit, so be forewarned. Today's run was an extreme run. Cold December, followed by a colder January, followed by a colder February. This is about the time of year that we can peek into early winter and see if our thoughts over the summer were correct. We can also begin to sort through analogs. I think Cosgrove's ideas have some merit in that winter will have a cold finish. He is just one of these guys who has seen a lot of weather, and has experience of decades of forecasting. But what if he is right, AND those of us(who are calling for a cold start to winter) are both correct? It has been a while since we have had a wall-to-wall winter. While I think wall-to-wall is unlikely, I do think a cold 2-3 weeks to start December, followed by 3-4 weeks of meh, followed by mid-late Jan into Feb cold...is on the table. But here is the extreme. And that might not look overly extreme, but given the configuration of the surface pressure maps below...there is an increasingly strong possibility of very cold temps being released into the lower 48. During a La Nina, the SE extent of the cold will often be more blunted than below. However, during weak La Nina winters...we can see that SE extent do exactly as modeled below. Not always, but there are precedents for that look. Over time, I have learned to look at surface pressure maps. I do this in order to see where the coldest air is. They are counter intuitive in that we look for BN heights at 500mb for but we look for AN heights at the surface. During winter, that can be a strong signal for cold air. Cold air anchors itself into the Canadian Prairies, and builds. As the season modeled progresses(below), the cold pushes. This is an "old school" winter setup where winter just kept coming. FTR, I am not saying this will happen, but it does catch my attention when modeling shows it - even LR ext modeling during shoulder season.

Today's GFS is the first of the operationals to get Nov 27th in range, albeit waaay out there. That is generally the earliest part of the potential window for sustained winter cold. Some modeling waits a few more days. The 12z GFS fits with what LR ext models have been saying. Now, we have seen head fakes at exaclty this range and at exactly this time of year during prior years. We have also seen LR ext models nail the forecast 4-6 weeks out. The GFS has a knack for spotting patterns at d16 during early winter. Here is a collection of maps from the morning and afternoon suites. 1. You can see the cold air configuration for DJF. The CFS flips flops between front loaded and back loaded winters, but generally this shows up regardless. I title this one "Remember when everyone used to talk about International Falls during cold outbreaks?" 2. The CFS daily runs 4x per day and can offer some fun solutions. I title this one, "Send it all to Cuba." This was from 6z. 3. The CFS at 0z gave us this lovely west PAC ridge. I title this one "Cold and dry." 4. As noted in the intro to this post, the 12z GFS now has Thanksgiving week in range. I title this one "Didn't we just do this yesterday?"

Wind chills at TRI dropped to 10F early this morning. I went running at a local state park this morning, and froze my tail off!!! Strava said the wind chills were 24F. Nope - they were 17F!!! That is probably the second coldest run I have done, but felt worse as I was exposed to the wind much more than other running routes. Last night, we had light snow until 10:00PM and likely much longer. This system was a powerhouse. We rarely get NW flow in Kingsport. We had several streamers. If this had fallen at night, we would have easily gotten 2-4" of snow. Just looking at some of the dates being kicked around for November snows...'93 and '14. Those went on to be benchmark winters for cold and snow. Will this winter follow suit? Time will tell.

Definitely some level of convective rotation. I have noticed it off and on today. Honestly, I am a little surprised there have not been reports of rumbles of thunder. Might just be too cold.

No particular order. Just thought I would share some LR ext maps and maybe throw in a seasonal. I am mainly looking at the time frame from Thanksgiving to Christmas. I tend to think the cold arrives just after Thanksgiving and holds to just before or right to Christmas. I think we have a very slight ridge or at least something to turn storms slightly northward if they slide across. I did throw in one turd burger control run just to show you how different the Euro Weeklies mean and control are. Pretty strong cold signal overall for early and mid December. There are much cooler weeks embedded within those 30 day maps.

The Euro Weeklies mean today is flat out frigid from just after Thanksgiving (onset TBD) to Christmas), and then hinting at the trough pulling west. I feel like I have seen that movie before! The control is the opposite! So, beware of shoulder season Weeklies. However, that is a really cold mean at this range. Yesterday's GEFS Weeklies were similarly cold. Looks like a PNA or EPO driven cold snap. It will be interesting to see if we can get November BN for temps...gonna be a close race.

Early score!

Haha. I am tickled that we have a snow thread on November 10th. @fountainguy97that 2014-2015 went on to be really, really good. You and John caught this synoptic setup early on. Generally, this is a money setup for NW flow w/ the shortwave. The Euro absolutely nailed this from way out.....I agree, @John1122. Fun to be tracking a system so early.

Same. That shortwave is what has interested me. It has been strong on modeling for several days. We picked up a burst here on Knob Creek in JC which made the ground white a few mins ago.

@Holston_River_Ramblerthe NW flow streamer off of Bays Mtn can be seen this AM. I drove through it on the way to JC. It is cranking. For anyone else, just look for the streamer SE of Kingsport along I26. I hit the stream right at Gray which is where it often sets up.

Very light dusting here in Kingsport on the roof tops and mulch. Shortwave on the 6z RGEM looks strong as Holston noted.

Haha. The CFSv2 is straight up frigid w/ its seasonal run today - bone chilling. February was just ridiculous.

Great post, and a great analog. Pretty amazing to see that type of correlation.

The Euro weeklies are crazy cold on the control run and very cold on the mean run. The Euro control drops a large amount of snow over the Tenn Valley for December. Now....we have seen the Euro be too cold for December. It is still shoulder season, but we take today's run and run with it.

The 12z CMC has a general 2-3" of snow over the Plateau and 6-12" over the Smokies. NW slopes in the foothills should see some snow as well - time of day dependent.

All of that to say, I think chances are increasing for high elevation snow and lower elevation snow showers in the foothills in prime NW flow areas around Nov 10-11. Either way, it should be very cold with afternoon wind chills in the upper teens to lower 20s in many places.

The 12z CMC vs yesterday's 12z CMC run is night and day different at 500. It is now almost identical to the Euro today at 12z. The GFS popping that low tells me that model is moving bigly to the Euro. We will see. Lots of support for the Euro solution where it had almost none yesterday with the exception of the 12z GEFS ensemble.

The 12z RGEM now has the system in range and has healthy bands of snow, rain/snow mix, and rain showers over the eastern half of the forum area - just like the Euro has had run-after-run for days. I am honestly surprised to see the Euro hold after missing so much last season and it being shoulder season.

The 12z CMC now brings the backside energy in the form of heavy snow showers on NW flow...complete cave by it.

Pretty interesting development on the 12z GFS and a fair amount of change. It pops a low over the Piedmont of North Carolina as opposed the northern stream dominate solutions it previously had. If true, the Euro(if it doesn't flip at 12z) has scored a "1 vs everybody" coup.

The November Euro seasonals are in. January looks decent. December could likely be colder than what it depicts, ESPECIALLY if the Euro weeklies from today are correct. Those weeklies look frigid through mid month. Warm Feb-April. But if we get Dec-Jan, we take it an run.

With snow cover in the foothills and higher elevations, most models(not the GFS) have temps 25 to almost 40 degrees below normal on those days.

The Euro is a bit deeper with this. The GFS deterministic is still further north but trending south. Interestingly, the GEFS lockstep with the Euro. Either way, this is a quick cold shot which means business. If the winter remembers what happens in November, we should see this reoccur.

The 12z Euro is leading the way on this 9-10th system. I can't say that gives me a lot of comfort as I have grown to trust the GFS in handling systems a bit better over the SE. I would guess this might amp up as we get closer and IF the system continues to create this type of energy in the lee of the Apps.

During the 70s, 80s, and 90s I rarely saw snow before Christmas. But my parents remember lots of snows in the 60s which were early. It certainly seems that early arriving winters are more normal now with February being less storm - kind of traded one for the other. Just a quick update so I don't have to post twice. The Euro continues to advertise a rather vigorous wave w/ the 9-11th cold shot. The GFS and CMC not so much. The Euro makes the most sense as that is a very common occurrence when cold are arrives which is that strong. Something to continue watching.