3/17/08 FCST: TX/OK/KS/MO/AR

[Shane Young]

(mods: this post is probably a mix of forecast and nowcast, please move it as you see fit)

I agree with Jeff that it's a major concern that the LLJ around 850 mb is forecast to shift well east by 21-00Z according to the RUC, as well as veer through the layer (a rather non-negligible layer of anticyclonic flow looks quite possible). If that happens, the early convection is the only hope.


Also agree about the cold front crashing south in terms of Oklahoma... so much for Tds near 60 in the Panhandle!

Mesoanalysis does show the dryline bulge. Also more clearing than expected.

Stuff looks to be coming together in a narrow axis near ABI, though. Max heating and some very healthy CAPE. I don't understand the mesoanalysis suggesting helicity is low along the dryline... perhaps it doesn't resolve the backs winds ahead of the bulge?


Good luck today everyone!
SY

 

[Ilya Neyman]

My original target still holds ivof and just south of the Red River, particularly from Wichita Falls south to Graham, TX.

Storms forming to the west now are in response to instability realized along the cold frontal convergence. Model progs back sfc flow and increase both sfc dews and mixing ratios steadily through the late afternoon and into the evening.

The timeframe I'm thinking is 4pm on for this area, with parameters becoming more favorable for supercells and an attendant tornado threat in this area later into the afternoon-evening.

As everyone has pointed out the negative really is the 850 flow somewhat veered, but more importantly not very strong. Still this may be compensated for by the strong speed shear and overall good low level shear, high dewpoints and very good heating taking place.

The question of interest will be whether or not that dryline bulge the NAM has been hinting at will materialize. If so, that should be enough to trigger storms north toward I-20 well ahead of the cold front. These would more likely be discreet.

There has been a corridor of sunshine across west-central TX and this may have the best potential to break the cap, at least locally with any differential heating boundaries or storm outflows.

May be heading out toward SPS shortly.

Ilya Neyman

 

[Derek Weston]

Just sat down to a computer to see SPC went MD risk. Absolutely don't see it if the RUC's 850 flow forecast verifies. It's nothing, and too far east.

To me, the SW(ish) Arkansas area after dark seems like a better bet for tornadic supercells...