
MESOSCALE DISCUSSION 0576
NWS STORM PREDICTION CENTER NORMAN OK
0205 PM CDT MON APR 07 2008
AREAS AFFECTED...SW OK...NW TX
CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY
VALID 071905Z - 072030Z
SUPERCELL DEVELOPMENT WILL BECOME MORE PROBABLE AFTER 20-21Z...AND A
TORNADO WATCH WILL LIKELY BE NEEDED BY ABOUT 20Z.
ADDITIONALLY...
THE 20Z CONVECTIVE OUTLOOK WILL BE UPGRADED TO MDT
RISK FOR THE SW OK/NW TX AREA. SURFACE OBSERVATIONS AND VISIBLE SATELLITE IMAGERY CONFIRM A
CONTINUED TREND OF LOW-LEVEL WARMING AND GRADUAL MOISTENING FROM NW
TX INTO SW OK...TO THE S OF A SLOW MOVING FRONT NEAR I-40 AND E OF
THE DRYLINE. THE 18Z SOUNDING FROM OUN...AS WELL AS SHORT TERM
MODEL SOUNDINGS...SUGGEST THAT A MIXED BOUNDARY LAYER WITH NEAR 60 F
DEWPOINTS AND SURFACE TEMPERATURES OF 78-80 F WILL MINIMIZE
CONVECTIVE INHIBITION AND CONTRIBUTE TO MLCAPE VALUES OF 2000-2500
J/KG THIS AFTERNOON. THUNDERSTORM INITIATION WILL BECOME MORE
PROBABLE BY 20-21Z...AS EVIDENCED BY THE RECENT ATTEMPT AT DEEP
CONVECTION ALONG THE DRYLINE IN BAYLOR COUNTY TX. SUPERCELLS WILL
BE LIKELY GIVEN THE SUBTLE FORCING...MODERATE INSTABILITY...
EFFECTIVE BULK SHEAR IN EXCESS OF 50 KT...AND EFFECTIVE SRH IN
EXCESS OF 250 M2/S2. THE STRONGEST STORMS WILL BE CAPABLE OF
PRODUCING VERY LARGE HAIL GIVEN THE STEEP MID LEVEL LAPSE
RATES...WHILE LOW-LEVEL MOISTURE/SHEAR SHOULD BE SUFFICIENT FOR A
FEW TORNADOES LATE THIS AFTERNOON/EVENING.
..THOMPSON.. 04/07/2008