
MESOSCALE DISCUSSION 1958
NWS STORM PREDICTION CENTER NORMAN OK
0209 PM CDT SUN AUG 23 2009
AREAS AFFECTED...CENTRAL AND SERN TX
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 231909Z - 232045Z
AN ISOLATED THREAT OF DAMAGING DOWNBURST WINDS AND PERHAPS SOME HAIL
IS EXPECTED TO INCREASE DURING THE AFTERNOON. A WW DOES NOT APPEAR
NECESSARY AT THIS TIME.
EARLY AFTERNOON SURFACE ANALYSIS INDICATES A STATIONARY FRONTAL
BOUNDARY WAS POSITIONED FROM ROUGHLY HOU NWWD TOWARD THE MWL
VICINITY. MID TO UPPER 60S DEWPOINTS RESIDE ALONG THIS
BOUNDARY...WHILE STRONG SURFACE HEATING TO ITS SOUTH HAS RESULTED IN
TEMPERATURES CLIMBING TOWARD 100 DEG F. LARGE SCALE FORCING FOR
ASCENT IS EXPECTED TO BE WEAK THROUGHOUT THE AFTERNOON...BUT STRONG
BOUNDARY LAYER DESTABILIZATION AND WEAK FRONTAL CONVERGENCE WILL
FAVOR SCATTERED THUNDERSTORM DEVELOPMENT...WHICH SHOULD QUICKLY
BECOME OUTFLOW DOMINANT GIVEN THE WEAK VERTICAL WIND SHEAR PROFILES
PRESENT ACROSS THE REGION. AS LOW LEVEL LAPSE RATES CONTINUE TO
STEEPEN DURING THE AFTERNOON...SURFACE DEWPOINT DEPRESSIONS WILL
EXCEED 30 DEG F...WHILE MLCAPE VALUES APPROACH 2000-2500 J/KG PER
RUC AND HRLY SURFACE OBJECTIVE ANALYSIS DATA. THIS THERMODYNAMIC
ENVIRONMENT WILL SUPPORT AN ISOLATED THREAT OF DAMAGING DOWNBURST
WINDS WITH THE STRONGER UPDRAFT CORES...BUT THE THREAT APPEARS TO BE
TOO MARGINAL TO WARRANT A WW.
..GARNER.. 08/23/2009
ATTN...WFO...HGX...FWD...CRP...EWX...SJT...