2/11/08 FCST: OK/TX/AR

[Billy Griffin]

Classic COLD CORE system for Oklahoma on Monday? Models suggest CAPE values of 1000 J/KG and an impressive amount of shear by Monday over much of Oklahoma. Stalled front will provide a focal point for thunderstorm initiation. Instability and shear should prove sufficient for severe storms and low-topped supercells with, perhaps, a cold-core environment for tornado development before the storms evolve into a convective mess.

 

[Billy Griffin]

Looks like we should add much of north Texas to this thread, as the cold front (becoming stationary) may set up much farther south than previously thought.

 

[Bill Schintler]

Chase target for Monday, February 11

Chase target:
Healdton, OK (12 miles west of Ardmore).

Timing:
Storms will be ongoing in central and in northern OK early in the period. Convection will then build to the south throughout the day and become surface based in the target area through 4 PM CST. Storm mode will be primarily multicell, with marginally severe hail likely. By early evening, storms will develop into an elevated MCS and track E along the Red River valley.

Synopsis:
It looks like the 00Z EDW sounding is missing. Other upstream soundings (AMA, MAF, EPZ, and ABQ) indicated steep mid-level lapse rates. The WV loop showed an interesting gravity wave over the TX panhandle between 19Z and 01Z. Flow aloft was weak, with the stronger westerlies located over the NWRN CONUS; and modest H5 height falls were noted over SRN CA. Large-scale assent was increasing and spreading E of a low-amplitude trough over NM and AZ. At the SFC, a WF extended E along the Red River from disorganized low pressure in SERN NM. S of this feature, temperatures were in the 60’s, while further N in OK temperatures were in the 40’s. LLVL moisture remained very limited except for ERN TX S of I-10 with SFC dewpoints between 50-55F.

Discussion:
Elevated convection will be ongoing early in the period in NRN OK/SRN KS along the H9 WF at the nose of a 45kt LLJ. LLVL moisture transport will be in full swing courtesy of the LLJ, and ST will blanket much of OK and NRN TX through 18Z. Clearing of the low clouds will take place W of I-35 by mid-afternoon, allowing for modest insolation. An axis of 55F dewpoints will build into extreme SRN OK by 20Z. MLCAPE’s will reach 2000J/kg as the aforementioned mid-level lapse rates of 8-8.5 C/km overspreads the moist axis. Increasing assent and UVM in the RRQ of a 60kt H5 speed max will erode CIN after 21Z. Flow aloft will be unseasonably weak, with deep-layer shear AOB 45 kts. A 30kt LLJ over backed SFC flow will result in (SFC-3km) SRH to 300m2/s2. During the evening hours, the LLJ will again increase to 40 kts, aiding in the maintenance of an MCS that will reach the DFW area by 04Z.

- bill
[FONT=&quot]10:00 PM CST, 02/10/08[/FONT]

 

[Jason Boggs]

I went ahead and added TX and AR to the thread.