Holston_River_Rambler

6z GFS kind followed the 6z NAMs in that it resolved the energy as a little bit better, but still not as good as some of the runs yesterday. The last few runs:

No precip type maps yet, but the qpf does seem a little south IMO:

18z Euro a little deeper and little slower with the energy. Gif with the 12z run and the 18z run:

#Imchasingthedeckpic

I'm sure some of you already ready MRX's disco, but I thought I'd post it here for posterity due to the topic points: 1) Severe. Very warm day is expected with a strong low level jet out of the southwest to the south of the frontal boundary. This will help to pump in warm, unstable air, along with good speed shear. Directional shear component is not as impressive, but with these strong winds helping to increase low level shear of 30+ knots in the eastern TN Valley, the chance for a possible tornado is present. Biggest question looks like it will be how much instability is available for storms to tap into. As usual the NAM is the most bullish with MLCAPE while most other forecast soundings showing a more moderate 300-500 J/kg, but all of these are pretty high for New Years Day. Think the biggest threat with possible severe weather will be strong straight line winds as this fast moving system makes it`s way through, but a quick isolated spin up of a tornado can`t be ruled out along the QLCS line. Think the main line will move onto the Cumberland Plateau around 00z, and quickly push east of the mountains by around 06/07z. 2) Flooding. This system will also have a good amount of moisture to work with as the jet helps to pull in Gulf moisture, and PWAT values rise above 1 inch in the Valley. This will help produce heavy showers and thunderstorms that could quickly dump a moderate amount of rain ahead of the line with isolated storms, and as the main line moves thorugh. High resolution models and Plumes indicate that 0.5-1.5 inches of rain are expected on Saturday which could lead to flooding of low lying and poor drainage areas by Saturday evening into early Sunday. But hopefully with this system quickly moving through the QPF amounts and flooding will be somewhat mitigated. 3) Snow. By Sunday we should get a brief break in precipitation chances as the line is to the east of the mountains, and the surface low begins to move through the Tennessee Valley. This will bring with it a strong shot of cold air Sunday night into Monday morning quickly dropping temperatures below freezing. With the 12z model runs some of the operational models are now indicating that the system will be stronger and slower than previous model runs. If this verifies it would mean that colder air and higher QPF amounts would be likely leading to more snow in the southern Appalachians and eastern TN Valley. Operational GFS has gone MUCH higher on snowfall amounts overnight, and in general most models have increased snowfall amounts overnight. Have bumped up official snow amounts in the Valley, but have been much more tame with amounts ranging from a dusting to quarter inch around Chattanooga, up to around an inch or more in the Tri-Cities... Higher amounts closer to 2+ inches can be expected in the higher elevations of the southern Appalachians and northern Cumberland Plateau. Have stayed closer to GEFS plumes which show a much lower amount compared to the operational models. Think that snowfall totals may need to be bumped up if models continue the trend of slower and stronger with the low, but would like to see multiple runs of the stronger/slower solution, and would also like to see ensemble members in better agreement with the slightly higher snow amounts. Have also undercut some guidance because ground temperatures are still going to be very warm (highs in the 70s/60s the days before) so snow will hit the ground quickly melt... Snow totals on the snow board will be much higher than what people actually see on the ground and on the roads (which is what most people actually care about). Weather quiets down by Monday afternoon and we get into a more mild and seasonable pattern thorugh the middle of the work week. Another trough will begin to swing through the eastern half of the US by the end of the work week... Temperatures are expected to be warm enough that most of the precipitation that falls Thursday into Friday will be all liquid, but in the overnight hours we could switch over to light snow in the Valley... But this is still a ways off and confidence will likely increase after we past this weekend system.

Beat me to the punch! The vort pass made me breathe heavily:

Yeah, the NAM looks better than 12z for sure: Still not as good as 12z GFS, but better than it was.

I had more mood swings watching that game than I do watching the NAM and Sref plumes come in lol. Sometimes I watched a series and thought we were regressing and then they’d do something to restore my faith.

I can’t bring myself to post it but if you want to see a true weenie run, check out the latest SREF-ARW that Ollie Williams posted over on Southernwx. Credit to him for finding it!

Pretty detailed disco by Webb and Masiello re: our little vort max: Some of y'all have probably seen the first coupe of tweets this pulls up, but some of the later replies get interesting. TL/DR: could be a last minute NW trend as it starts to unfold.

Still not as nice as the GFS, but better:

12z Euro is deeper and slower with the energy than its 0z run as it crosses the southeast.

There was a point when I started to wonder if Fulmer had come back to call some of those “up the middle” runs lol!

Really nice vort pass for eastern areas on the 12z GFS:

@Carvers Gap

NAM was pretty flat with the energy for the wintry threats at 12z, but the RGEM was still looking pretty stout:

6z Euro looks the best I've seen it look with the energy for the wintrier threats with this system: I don't have the precip type maps yet, but here is the 6 hr accum. precip

It seems like the GFS has been trying maybe one out of every 2 or 3 runs, to try to bury some energy in the gulf. Here are 9 runs centered on 12z Thursday, January 13: I count 2/3 of those runs showing either a vort of some form in the Gulf or diving towards it. The Euro Control overnight had something similar. I wish I had access to its relative vorticity maps for a more similar comparison, but the best I have is the 500mb wind: As far as I can tell, this is the first time the Control has shown something like this. All of it is a way, way out there in time, but anything remotely resembling energy diving towards the Gulf is always something I'm interested in. Overnight extended range ensemble gifs: (nice ending look IMO on the GEFS above) Most RMM plots look fairly similar now. I'll use the Euro since IMO it has been the most consistent with the MJO mess: Just looking at the tropical convection in the western Pac, I don't see much to get too excited about, but I guess we'll see:

By popular demand I went ahead and updated the title and initial description post for this thread.

But hey, at least the 18z Euro looks marginally better for Sunday night.

I need more beer than I have after that ending.

Little nervous about this game. IMO Perdue is good and although I haven’t kept up with them at all, based on the commentary and how they’re playing (that fullback!) I suspect they were a few red zone plays away from a much better bowl than Music City.

I went ahead and rolled the dice.

That one went over my head, lol. Good opening run for the second half, let's hope that portends well for the Hooker-Tillman connection.

This is def. one where I think ground temps will play a role. Couple hours of moderate snow would be a win IMBY.