Spreading Anvil at Sunset, Scurry and Kent Counties, Texas, May 12, 2009

The Eastern Permian Basin was included in a Slight Risk Category by the SPC on May 12th due to forecasted and observed steep mid level lapse rates, rich surface moisture, and strong surface heating west of a sharpening north south trending dry line for late afternoon and early evening. A Severe Thunderstorm Watch was eventually issued as convection initiated, overcoming a weakening capping inversion. SBCAPE values were rather impressive, exceeding 2500 J/kg, but mid to upper level speed shear, although increasing from earlier 1200Z sounding with respect to 0000Z soundings at MAF, were 40-50 knots of zonal west to east flow. Several images were taken of multi-cellular thunderstorms near the townsite of Ira in Scurry County at 0130Z looking from west to the east and northeast (northeast Mitchell, southeast Scurry counties extending into Kent County) at spreading anvils of mature/dissipating stages highlighted from setting sun. The first image is sun highlighted spreading anvil of mature/dissipating storm near Scurry/ Mitchell county line. The second image is looking further northeast into Kent County at spreading anvil underside with large Mammatus