Holston_River_Rambler

I think there may still be some shifts until the cutter works its way through by Saturday.

18z GFS is rolling. Time to spin the wheel of fortune.

Don't forget posting some long range hi-res precip output to get hopes up:

At least we still have the storm tomorrow to run into and change up that big low.

There’s a lot riding on how much thunder we get tomorrow.

At least we still have one of the Euro machine learning models:

Kind of like the GFS at 12z yesterday. EDIT, 18z.

As far as I can tell the second wave is digging like the 6z control so far, further west and slower: 12z on the left, 0z on the right:

So far a taller western ridge on the 12z Euro:

6z Euro control was a lot slower and deeper with the trailing wave. It almost looked like it was trying for a suppressed Miller A:

6z Euro was taller with the western ridge. We’ll see what that means on the control in about an hour or so.

It does look taller so, it could be part of why the s/w digs more. But I think a lot depends one how those PNA ridges tilt too.

I think it’s just a matter of which s/w the focus is on. The first one is trending more weak sauce. But the second one is trending deeper and slower, at least so far.

Actually I thought that was the 12z OP, but that is the 12z Control. Here is the 12z OP at the same time stamp: apologies.

18z EPC control dug and slowed the trailing shortwave a lot more: 18z control on the left, 12z OP on right Doesn't quite go out far enough, but I suspect that was about to be a nice Miller A.

Cross polar flow and a big low spinning in the west Pac off the coast of Mexico. Snow in Louisiana: Obviously out in la la land but that would be something to see.

There is a wild set up past hr 260 on the OP GFS this evening.

Yeah that was like the worst possible weather scenario if you want more than flurries and virga outside of Arkansa and maybe Memphis, Dyersburg and Union City. Not saying it will happen, but a way to fail, as is the custom.

Yeah that looked like a big jump to hold more back. Let’s see if it can carve its way toward the gulf.

This may end up being very similar to what others have said, but I'm just now getting time to type something up. With that caveat, here are Holston's 2 cents. This is mostly just about the moving parts, so I'm just using the 12z Euro for illustrative purposes. I am not implying it has the solution. We start at hour 0: We have some blocking at H5 in the NAO and AO domains, illustrated here by the red squiggles. Underneath that we have a broad anticyclonic circulation over most of Canada. On the lower fringes of this we have two stout shortwaves, here usefully labelled as Cutter A (the storm from yesterday) and Cutter B (Friday's storm). Now watch as these systems evolve. I can't control when these gifs start and stop, so you may have to watch it a few times to see all the interactions: The first storm rotates up and through the Canadian maritimes as the overall broad anticyclonic rotation continues. But also notice just how many stout shortwaves there are over Canada rotating in that broad circulation. It almost takes on the look of a star at one point, with a nice shortwave at each point. Watch especially the two over Yukon and British Columbia. They kinda sorta try to phase at the end. All the while our cutter does what we expect and cut up through the OH Valley. A snapshot of all this at hour 48: Cutter A has added to what I'm very scientifically labelling a "Fujiwara mess" and a tall ridge just off the west coast and into AK. I know most people here know this, but if not (it's ok) the fujiwara effect is when two cyclones kind of dance around each other. Three huge midlevel, cuttoff cyclones all interacting, meandering, and spinning over Canada, as the ridging over Greenland and that off the Pac coast try to pinch it off. As this mess evolves over the next 48 hours, the two cyclones over western Canada get more strung out and evnn interact with the Friday cutter, creating a long ribbon of vorticity looping from norther Alaska, down into norther Missouri, and then across the Ohio valley and into the Canadian maritimes. While all that is going on, the shortwave that first interests us is coming onshore around hour 87 in N. California. the other thing I would ask you to notice in this is a shortwave associated with the subtropical jet out in the Pacific, southwest of California and associated vorticity extending across Mexico and into the Gulf. The shortwave I have labelled "Part A" is going to swing under that huge vorticity ribbon and aim directly at the TN Valley: A little vorticity advection, a little flow backing for a smidge of Gulf moisture, a healthy dose of frontogentic forcing I'm guessing with the arctic air and you get the flat, overunning precip event: So we have that and in some ways its not too complicated. Now let's turn back to that ribbon of vorticity left out from the fujiwara sheared mess: In the above picture the shortwave that was producing the overrunning anafront stuff is now shearing out under the pressure from basically a piece of the tropospheric PV over St. James Bay. It's the resolution of the fujiwara mess that's getting interesting now. Look at that shortwave diving down through the Rockies. There's also a new shortwave coming on shore in CA and what's left of the STJ energy i mentioned above. It's this shortwave over the Rockies that's producing the "almost" Miller A solutions: It dives down, some of that STJ energy gets involved and we shoot for Florida panhandle cyclogenesis: There is a lot more to dig around in here, but that is all I have time for, for now. All kinds of moving parts, so it is astounding that models have been as consistent as they have been with some sort of system from as far out as they have seen it.

This is such a weird complicated set up I'm going to try to do a bigger post later with all the elements going into this potential.

IMO we wait until this next cutter is out of the way.

This is high stakes territory snowbird, we've reached the land of "extrapolate the NAM"

It's the control, so the resolution is lower, but it looks quite a bit slower that the OP for one thing. Here is the 0z OP for the same time: The end result might not be any different, but I like the idea of 2 shortwaves interacting near the MS river and Gulf coast: There's room to amplify and a semi phased shortwave trough to go negative at the right longitude for us. You can see it trying to do it on the 0z Euro. See how as the shortwave (indicated by the blue lines) rolls overhead precip increases pretty quickly over east TN. Maybe if it can dig more and slow a bit we get more of a Miller A type solution.

That's definitely an interesting look at H5 on the control, and that is after the front has washed out.