Isolated development of severe thunderstorms is possible this evening across parts of western north Texas. Most of this activity will be elevated in nature along and behind a stationary cold front draped from about Wichita Falls southwest towards Big Spring. Because these storms will be elevated, the threat for tornadoes is expected to be very low. Large hail will be the main threats along with frequent cloud to ground lightning. One storm recently attempted development just south of Munday in in Knox County, but it hasn’t made much progress over the past half hour. Additional storm development is possible across this area within the next couple of hours, so residents in the area will need to keep an eye on the sky this evening.
VISIBLE SATELLITE IMAGE AT 5:55PM CENTRAL TIME
Mesoscale Discussion 0529 NWS Storm Prediction Center Norman OK 0540 PM CDT Thu Apr 20 2017 Areas affected...Northwest TX...OK Concerning...Severe potential...Watch possible Valid 202240Z - 210015Z Probability of Watch Issuance...60 percent SUMMARY...Thunderstorms are expected to develop across northwest TX into central OK this evening. Large hail is the primary risk with this activity. DISCUSSION...Surface front has stalled from east central OK into northwest TX early this evening. With surface temperatures in the mid 80s across northwest TX a corridor of modest instability has developed from the TX South Plains to near the Red River. Latest visible satellite imagery depicts a thickening CU field along the front with deeper convection over Haskell/Knox Counties in TX producing weak echo returns. As LLJ strengthens across this region into southwest OK this evening it appears a marked increase in thunderstorm activity will be observed. Numerous elevated thunderstorms should blossom north of the boundary and adequate mid-level lapse rates are in place for robust updrafts. Greatest risk with this activity should be hail.