11/29/06 FCST: KS / MO / OK / TX

Tonight's NAM run actually has an interesting setup for Wednesday, with moderate instability developing ahead of the plunging cold front by afternoon. Flow at all levels are relatively strong, and shear profiles will be favorable for supercells (0-6km shear of 50-65kts, 0-3km SRH >250m2/s2, etc). Heck, tonight's OUN sounding only had ~700 j/kg SBCAPE, and a decent small supercell developed and moved across portions of central and north-central Oklahoma.

Of course, one of the biggest issues may be storm mode -- a rapidly-moving cold front with strong convergence along it doesn't scream "discrete convection"! The NAM is currently showing the deep-layer shear vector to be towards the northeast immediately along the front, though showing a greater easterly component the farther south of I40 one goes. Depending upon what kind of dryline can develop, there is the chance for a better shear vector - initiating boundary orientation that would favor discrete supercells. The GFS appears to be more aggressive with the cold front movement, which I'm airing towards given that these strong fronts tend to come barreling down the Plains in a fashion faster than the models indicate. So, I'm setting my very-preliminary sights on far northern Texas. If the cold front takes on an E-W orientation down there, any storms that develop would be undercut by the southward-moving front.

With 60+kts at 500mb, I can't imagine many storms will be moving less than 40kts. At least it's not in the 'rocket-boosters required' category that characterized most of the March and April chase setups. And hey, I can't deny a chase that could end with me arriving at my apartment in sleet or freezing rain! I included MO and KS in this given the potential for elevated activity, but I think the best potential for supercells and any tornadoes is south of I40 (and probably south of the Red River).
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I agree with Jeff that the best area for Wednesday's setup will be south of the Red River. The latest NAM run (12z Tue) shows a surface low over Western North Texas by 00z, and indicates discrete convection firing over Central & North Texas by 18z, then heavier convection by 00z. I'm not sure if the convection at 18z is just elevated warm air advection storms, or it it's surface based storms firing off the dryline. Either way strong dynamics will be in place and storms will fire.

The big issue in my opinion will be the cirus deck. The GFS brings in high relative humidity values at 250mb from the subtropical jet, and that may inhibit the already marginal instability. In these late fall/early winter setups you need all the surface heating you can get! If I could chase I'd head up to near or a bit east of the Wichita Falls area. I wouldn't go after the storms firing off the cold front in Oklahoma. It'll be surging way too fast and any storms forming along it will be linear.

Given the 30-35 knot 850mb jet from the south, and strong southwesterly 500mb flow, I'd say low topped supercells are possible with a few tornadoes across North Texas from as far south as I-20 north to Wichita Falls east to I-35. I'd be much more confident if that cirus deck wasn't fmoving in from the southwest.
This got intresting really fast, sux I just took an extended vacation down to Shreveport, La. for thanksgiving and I cant take off another 2 days this week
:( That southern wind is bring alot of warm air and moisture from the gulf which is not good for us up here in the land of Oz (we really dont need another bad ice storm like we had couple years back) so I am going to be inside all day watching from here. I agree with Jeff as well all the fireworks will be down in Texas and Oklahoma. Jeff also pointed something out last night that might play into tommorows chase and that is the sunsets early this time of year which means this is going to be a night event which is not my kind of chase. These storms will be chasing "Yall" down there and they'll be packin a punch . It will be fun watching this storm system develope over the rockies today. It's the battle of the air mases over the heartland. Today in Wichita its suppose to get up to 70 deg then suppose to drop from 45 in the afternoon to 27 deg by the evening. From Miami to Alaska in 24 hours lol theres no place like home. Good luck tommorow everyone whos brave enough to make the trip and have a safe trip back home espeacilly if you live up north road conditions will be horrible for most of the night wednesday and all day thursday. I guess mother nature wants to kick things off with a bang this winter!!!

I like the Wichita Falls to Gainesville, TX area for tomorrow and will be going out for a late season chase. I'll take any help I can get from spotters online tomorrow. My email is [email protected] or cell is 940-783-2136. Internet access is hard to come by in that area so I'll be flying blind except or my Blackberry. Got to love it!