2/22 FCST: N TX/S OK

Anyone afflicted with severe SDS, already located in N TX/S OK, looking for a "warm up" chase for 2005, and able to chase Tuesday might be somewhat intrigued by the forecast for then.

Both ETA and GFS are progging some interesting parameters, but your target would be quite different depending on which you may choose to believe. ETA would have you east of I-35, GFS substantially west.

Both are presenting "decent" sfc theta-e's (for Feb) ATTM, LI's as low as -8, good (but weak) directional shear, some UVV's at 0Z and 6Z for 2-23, and decent upper level support. The biggest negative is weak speeds from sfc on up through 700mb, so expect any storms to lose severity quickly.

If the forecast gets any worse, forget it.....but if it gets better, well, you have your heads up!

Bob
 
Still looks to be a legitimate threat of supercells later today, albeit to the southwest of the orginal suggested target region. Big Bend region of TX starting to take shape for some action later today. Morning DRT sounding showing ample deep moisture in place, with CAPE > 1000, but weak mid-level flow. Mid-level jet streak within subtropical stream forecast by 20 km RUC to slide into extreme sw TX this evening, leading to surface pressure falls (improving low-level flow, 0-3 helicities up to ~ 150 by late afternoon) and much improved SW mid-level flow, underlain by ESE winds of 10-15 knots. Deep moisture currently bottled up by weak sfc ridge reinforced by low-level fog with axis running through SJT, but this appears to be breaking up slowly, and should allow low-mid 60 dewpoints to press toward the nw, perhaps as far as MAF. Adding the DRT low-level moisture to MAF gives a pretty favorable large hail sounding. However, better low-level shear remains closer to the Rio Grande. So, may be some reason to keep an eye on the region from MAF-SJT-DRT today. Checking SPC's forecast, they seem to be interested in the same region.

Glen
 
Chase target for today, February 22

Chase target: Hamlin, TX today.

Storm initiation timing 4-5 PM CST. The main severe threat will be large hail and winds to 70 mph.

Discussion:
The east-west oriented baroclinic zone in that region will sharpen later this afternoon in response to shortwave energy which will spread east from NM while the left-exit region of an 80kt UL streak approaches. Temperatures near 70F and dewpoints around 55F will allow for MLCAPE’s to exceed 2000 J/kG. Additionally, SERLY upslope surface flow will result in impressive (February) theta-E’s reaching 330K (although the elevation is only 1700 ft at Hamlin, it increases rapidly a short distance to the west. Dickens, TX is just over 3000 ft. 0-3 km SRH’s will locally exceed 300 m^2/s^2 as a 30kt LLJ noses into the area after 22Z. Deep layer (0-6km) shear will reach 40-50 kts.

bill
 
Mexican supercell

Right moving isolated (super)cell WSW of Del Rio moving towards the Rio Grande. Mid-level rotation is evident from the base scan (very far away from the radar), which leads me to believe a nice LP storm with some decent hail is heading towards Texas. This will probably be the most exciting cell of the day considering the anvil blowoff and setting sun are preventing further surface instability. Mexican supercells are exciting to arm chair chase. I would venture out on my own if the risk of getting stuck in a 3X3 jail cell for speeding weren't on the list of hazards. Ready for March now.
 
Yeah, that cell has looked good, and bad, at times. Appears to be sliding down the northern side of a NW-SE oriented ridge - look at the RAP radar with the terrain feature turned on to see this for yourself. Eventually it runs off the ridge - and not sure what the cell will do then, but may follow one of the river valleys out to the east and eventually cross over into TX. Unclear if anything interesting will emerge out of the cluster of storms near San Angelo, particularly with the void in surface observations upstream in the inflow, but there are at least slim propsects I suppose. SPC went with a SVR box, with mention of tornadoes possible. A few SVR have been issued now around SJT, so could probably switch this over to a nowcast if others are interested in following the event.

Glen
 
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