Summer-Fall 2024 Weather Disco Med/Long Range

[Carvers Gap]

12z ensembles depict a fairly typical cold start to winter with sever cold over Montana bleeding southeastward into the Upper South w/ the Apps as the demarcation line.  That looks has delivered some crazy cold into portions of our forum area during the past decade and a half.  I suspect we see something similar again.  The 12z GEFS, EPS, and GEPS all show another strong cold shot around d12-15.  It is possible they are a bit ahead of things....it is also possible they are sensing a very strong cold shot.  When cold is that strong on an ensemble at range....reality "could" be much colder.  

[Carvers Gap]

Go back and dig through our Nina Decembers and compare them to these ensembles at 360.  This look often delivers pretty significant cold shots.  HUGE grains o salt at this range, but a decent signal at range.  

 

[*Flash*]

5 hours ago, Carvers Gap said:

The 12z GFS continues to advertise a vey sharp change in our weather regime.  Winter is on its way, folks.  That is not a promise of snow, but there are certainly chances on the GFS.  LR ext(weeklies) models washed out the strength of the troughs heading east.  Now that the pattern is in range, it is a bit more chippy than what we saw on the Weeklies.  Some STRONG amplification showing up.

Don't quote me on this next month, but based on how the past month has gone, I'm fine with sNOw in the short term. Just give me seasonal temps that get me in the holiday spirit. That's all I can ask for the final six weeks of any year. For west/middle TN, any accumulation before the new year is gravy.

[Carvers Gap]

Flow is fast, but we can score with that setup on the 12z GFS and CMC.  I am not talking about one particular event, just the general setup.  That is a good setup for John and folks in NE TN, SE KY, and SW VA.  I am halfway eyeballing a weak overrunning event as well, especially for middle and western areas.  That look is a shallow trough with the area of confluence around the KY/TN border....and kind of offset eastward just a bit.  That allows for the low left section of the trough to be attacked by return flow.   Potential is there.  12z GFS is honking later in that run.

[John1122]

The 18z is showing basically what Carvers mentioned above. Nice snow event for the Eastern Rim, over in Western NC, 40 and north. 

[John1122]

It doubles down and dumps on 40 and north again from Arkansas and East. 

[John1122]

That'll do, GFS. 

[Carvers Gap]

Happy hour, baby!!!!

[Carvers Gap]

The thing I like, and it is in fantasy land...is that big 1055 high late in the run.  When we see those in December, that is a good sign if it verifies.  Big highs in Montana will often find their way here as long as they are on the east slopes.

[Carvers Gap]

That high gets to 1065 I think near the Yukon.

[Carvers Gap]

This is what I am looking at.  It was there at 12z, but not this crazy.  The 18z GEFS has it as well.  The GFS has an uncanny ability of spotting early season cold.  I am NOT saying this is going to happen, but it is worth noting even at this range.  Just a few snippets from 18z.

 

[Carvers Gap]

I was thinking that looked like the strat was getting hammered pretty good.  Two lobes at 30mb and 50mb around this timeframe.  I don't know if I would call it a split, but definitely looks dislodged.   Reading in the MA....I would add to their discussion and say that active Pac jet may be the cause of it.

[1234snow]

I guess the 18z GFS woke me up from my “fall” hibernation

[Daniel Boone]

22 minutes ago, Carvers Gap said:

I was thinking that looked like the strat was getting hammered pretty good.  Two lobes at 30mb and 50mb around this timeframe.  I don't know if I would call it a split, but definitely looks dislodged.   Reading in the MA....I would add to their discussion and say that active Pac jet may be the cause of it.

Yeah, made mention over there about that stretched PV yesterday i believe and how if we bridge over that and it gets forced on down we'd be in business. That depiction from 18z sure looks to be accomplishing that. CPF coming on down until it bridges on over . 

[Carvers Gap]

28 minutes ago, 1234snow said:

I guess the 18z GFS woke me up from my “fall” hibernation

I just want summer to be over before met winter starts!!!  LOL. 

[nrgjeff]

AI versions tend to favor the colder GFS over the ECMWF. If the EC ends up winning, we can look forward to a forced line of severe thunderstorms - with zero separation of cells. Meh.

[John1122]

Anyone want to start a December thread? Models are now in range and the Euro, as Jeff noted, tossed an early December slider across the plate.

[AMZ8990]

2 hours ago, John1122 said:

Anyone want to start a December thread? Models are now in range and the Euro, as Jeff noted, tossed an early December slider across the plate.

Will do

[Carvers Gap]

45 minutes ago, AMZ8990 said:

Will do

Yeah, man!  I had it in the queue for you or John or holston.  AMZ definitely brings the cold when he starts a thread.  December is gonna be a cold thread.  Take it to the bank now.

[Carvers Gap]

Ladies and Gentlemen, here we go...from MRX this evening.  Modeling nailed this from a ways out.  That is good, but modeling has more on the table after this.

 

Key Messages:

1. Gusty winds expected across the higher elevations of the southern
Appalachian Mountains Wednesday through Saturday. Gusts from 30 to
40 mph will be common.

2. Breezy winds in the lower elevations across the valley Wednesday
through Friday. Gusts from 20 to 30 mph will be common.

3. Wind chills in the 30s and 40s for valley locations Thursday and
Friday during the day. Wind chills in the teens for the higher
elevations of the southern Appalachian Mountains.

4. Light snow accumulations likely across the northeast TN and
southwest VA mountains. Amounts of 1 to 2 inches are expected.
Isolated 3"+ amounts are probable..

5. A return to normal temperatures by Sunday.

Discussion:

Active weather for the back half of the work week, with a shock to
the system as we transition fairly quickly from shorts weather to
parka weather. Well see a quick-moving weather system passing
through the Ohio River Valley to kick things off. Expect the system
will move in Wednesday night into Thursday night, bringing with it a
blast of colder air as it moves south. Because of this setup, were
looking at some light snowfall in our area from Thursday night
through Saturday morning. As the weekend progresses, this system
will move out and high pressure will start to build back in,
bringing temperatures back to normal by Sunday.

Snow:
Were in for some of our first snowy weather in our higher
elevations, and we might even see a few flakes overnight in the
valleys of northeast Tennessee and southwest Virginia. The big
question is how much moisture well actually get. Right now, it
seems like we can expect around 1 to 2 inches of snow in the
mountains of northeast Tennessee and southwest Virginia, with some
spots possibly getting up to 3 inches. Theres about a 50-75% chance
of seeing those higher amounts in isolated areas when looking at
probabilistic guidance. Further south, places like Newfound Gap and
Mt Leconte are looking at around 0.5 inches of snow due to less
moisture. For now, were sticking with these snowfall estimates, but
theres still some uncertainty. The actual snowfall could vary quite
a bit, from 3 to 5 inches, depending on how much moisture we end up
getting and the exact position and strength of the low pressure
system to our northeast. Some of the high resolution models are
indicating we could see some enhanced moisture off the Great Lakes,
which can really increase snow amounts in a narrow area...But just
as likely is the low shifts 30 miles to the north and much of the
moisture stays across Kentucky and West Virginia. Also complicating
the forecast is how warm the ground will be early this week leading
into the snowfall which could melt much of it upon contact.

Wind:
On Wednesday, were looking at some pretty gusty winds as a
weather system moves through. Expect winds of 30 to 40 mph across
the higher elevations in eastern TN, southwest NC, and southwest VA.
As we move into Wednesday night through Saturday morning, those
strong west to northwest winds will stick around, keeping the gusts
going at 30 to 40 mph in the mountains, with some spots possibly
hitting up to 45 mph. It still appears we will remain below High
Wind Warning criteria, but a Wind Advisory is still very much in
play.

On Thursday and Friday afternoons, as the winds mix down to the
surface, we`ll also see breezy conditions in the valley areas, with
wind gusts from 20 to 30 mph being pretty common. By Saturday, the
winds will start to calm down as the weather system moves out to the
east.

Temperatures:
After the cold front moves through on Thursday and
Friday, its going to feel a lot more like January. Daytime highs
will be chilly, and with the breezy winds, it`ll feel like its in
the low to mid-30s for most of the area. In the higher elevations,
wind chills will dip into the teens. Keep in mind, these are daytime
wind chills, not overnight temperatures. While these wind chills
arent out of the ordinary for us, they`ll definitely be a bit of a
shock given the recent warm spell. If youre planning to spend time
outside, make sure to dress warmly and be prepared for the cold
especially the kiddos waiting for the bus in the morning on Thursday
and Friday!

[Carvers Gap]

[Jed33]

Wow that seems really bullish for the northern valley! I guess we will see. I can only assume they are counting on the higher ridge tops in these counties to produce the accumulations.

[matt9697]

Front must have come through here; really windy now. 

[fountainguy97]

2 hours ago, Jed33 said:

Wow that seems really bullish for the northern valley! I guess we will see. I can only assume they are counting on the higher ridge tops in these counties to produce the accumulations.

12z NAM and HRRR have what I best describe as a clipper style batch of precip moving through Thursday night.  This should be enough for snow across the valley. Temps are close but should be good.

then the NW flow boosts totals for the usual suspects.

[Carvers Gap]

@PowellVolz, all right man.  Time to jump in!

[Daniel Boone]

Temperature dropped 15 degrees in about 45 minutes here this Afternoon. We are now at 45.7 . 20 degrees below the High.