SPC AC 111620
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1120 AM CDT TUE MAY 11 2010
VALID 111630Z - 121200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM MUCH OF OK/KS INTO THE
LOWER OH VALLEY...
...NORTHWEST OK/SOUTH CENTRAL KS...
MORNING WATER VAPOR IMAGERY SHOWS A DISTINCT SHORTWAVE TROUGH MOVING
ACROSS SOUTHERN AZ/NM. THIS FEATURE IS WELL HANDLED BY THE 12Z
NAM/GFS AND IS EXPECTED TO TRACK INTO THE TX PANHANDLE AND WESTERN
OK THIS EVENING. AS THE TROUGH APPROACHES...SOUTHERLY LOW LEVEL
WINDS ARE FORECAST TO STRENGTHEN RAPIDLY ACROSS TX/OK. THIS WILL
RESULT IN RAPID LOW LEVEL MOISTENING AND DESTABILIZATION OVER MUCH
OF NORTHERN OK/SOUTHERN KS AROUND OR AFTER DARK. FORECAST SOUNDINGS
IN NORTHWEST OK INDICATE AN EXTREMELY UNSTABLE ENVIRONMENT WITH VERY
STEEP MID LEVEL LAPSE RATES AND A WEAKENING CAP. ALSO...WIND
PROFILES STRENGTHEN DRAMATICALLY DURING THE EVENING WITH EFFECTIVE
SHEAR OF 40-50 KNOTS AND EFFECTIVE SRH VALUES OF 200-400 M2/S2.
THIS SUGGESTS THE RISK OF SUPERCELLS CAPABLE OF VERY LARGE HAIL AND
A FEW TORNADOES DURING THE EVENING OVER NORTHWEST OK...WITH SGFNT
HAIL THREAT SPREADING NORTHEASTWARD INTO CENTRAL KS BY LATE EVENING.
CONSIDERED AN UPGRADE TO MODERATE RISK FOR PORTIONS OF THIS
AREA...BUT HELD OFF DUE TO CONCERNS OF CONVECTIVE COVERAGE.
...REMAINDER OF OK...
A VERY MOIST AND STRONGLY UNSTABLE AIRMASS WILL BE PRESENT
THROUGHOUT OK THIS AFTERNOON AND EVENING...WITH VARIOUS MODEL
SOLUTIONS SUGGESTING CONVECTIVE INITIATION POSSIBLE ACROSS THE
STATE. WEAK FORCING SUGGESTS AREAL COVERAGE OF STORMS WILL BE
LIMITED. HOWEVER...THERMODYNAMICS AND WIND PROFILES ARGUE FOR A
RISK OF SUPERCELL STRUCTURES IN ANY STORMS THAT FORM TODAY.
...SOUTHERN MO/NORTHERN AR INTO LOWER OH VALLEY...
SURFACE BOUNDARY CURRENTLY EXTENDS FROM NORTHEAST OK INTO SOUTHERN
MO. DEWPOINTS ARE CLIMBING TO THE SOUTH OF THE BOUNDARY WITH MID
60S VALUES EXPECTED BY AFTERNOON AS FAR EAST AS WESTERN KY/SOUTHERN
IND. BROKEN CLOUD COVER WILL SOMEWHAT LIMIT THE DAYTIME
HEATING/DESTABILIZATION. HOWEVER...A RATHER WEAK CAP AND
CONVERGENCE ALONG THE BOUNDARY WILL LIKELY BE SUFFICIENT FOR
SCATTERED THUNDERSTORM DEVELOPMENT. VERTICAL SHEAR PROFILES IN THIS
AREA ARE STRONG ENOUGH TO SUPPORT A RISK OF ORGANIZED MULTICELL TO
SUPERCELL STORMS CAPABLE OF LARGE HAIL...DAMAGING WINDS...AND EVEN
AN ISOLATED TORNADO.
..HART/SMITH.. 05/11/2010
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z
|
