12/23/09 FCST: TX/LA

[Darren Addy]

Going out on a limb and starting a forecast discussion for Wed.

The potent cyclone bringing blizzard conditions to the northern plains midweek will also be bringing mid-60's dewpoints, shear and helicity to eastern Texas and western Louisiana Wed. evening/night.

CAPE and LIs don't look like anything to write home about, at this point, but the GFS initiates SFC-based thunderstorms from near DFW to the Houston area on Wed. afternoon. 0-6km shear in 55-70 range would mean supercells, at least initially. Surface winds look nicely backed in that area, but a little on the light side. All-in-all, pretty marginal at this point, but considering the week that it is, perhaps enough to get southern chasers out of the house for a while?

 

[W. Grant Dade]

I have been watching this system for a few days now. Looks like a fairly good possibility of isolated tornadoes across east TX and LA. Surface winds late Wed pick up a bit out of the south southeast around 15 to 20 knots. 0-1km shear is over 25 knots and 0-1km storm relative in flow is around 30 knots. As you mentioned the shear is more than enough for supercell development. I really feel there will be a few tornadic, low topped supercells before the convection mode becomes linear thanks to forcing. Unfortunately I think most of the action will occur after sunset. Looks like another high shear low instability event possible.

 

[Dennis Dennison]

I live in Arizona and tonight there was quite a lot of energy go through the area, with thunderstorms and hail. High winds also present. so consider this additional energy and temperature change into the Texas equitation, and maybe even into Oklahoma area.

 

[Jeff House]

Thanks for some ground truth out in Arizona. With all this high technology the window is still one of the best weather instruments. OK, today in North Texas we have the sun breaking out and the pre-frontal trough in the area. Still looks like a low top setup and daylight is limited. However directional shear is good and speed shear will improve later, hopefully before sunset.

I'm looking at the intersection of the pre-frontal trough and quasi-warm front lifting north through eastern Texas. That WF could make it as far north as the Red River; therefore, my personal bullseye is slightly north of that from SPC. This is a low probability setup (not the 10% but the trees, daylight, roads, etc) but work is slow and why not try for a Christmas present? Good luck and drive safe.

 

[Darren Addy]

The fact that there is already a MD for the area gives one a little hope for something before dark, but I'm not wild about the fact that the surface/inflow winds look to be 180 degrees to the 500mb winds. Still, just seeing something supercellular in late December would have to be considered a treat.

 

[Bryan Draper]

Looking like the area around and to the west of DFW metro might be able to hold some storms. MD was out for that area a bit ago, backing winds came farther west than they we're thinking I believe. How ever looks like its going to be a linear set up