SWODY1
SPC AC 121600
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1100 AM CDT FRI JUN 12 2009
VALID 121630Z - 131200Z
...THERE IS A MDT RISK OF SVR TSTMS PARTS OF ERN OK...NRN AND
CENTRAL AR...WRN TN AND NRN MS...
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE SOUTHERN PLAINS TO THE
CAROLINAS...
...SYNOPSIS...
DYNAMIC FEATURE OF INTEREST AS RELATED TO SEVERE CONVECTIVE
POTENTIAL THIS FORECAST PERIOD IS THE MID LEVEL S/WV TROUGH
CURRENTLY MOVING EWD CENTRAL KS TO NRN OK EMBEDDED IN RELATIVELY
FAST MID/UPPER WLY FLOW THAT EXTENDS EWD TO ATLANTIC COAST. A
DERECHO HAS DEVELOPED IN ADVANCE OF THE TROUGH AND IS TRACKING
RAPIDLY E/ESEWD ACROSS NERN OK ON INTO LWR MS VALLEY THIS AFTERNOON.
A S/WV TROUGH ROTATES INLAND SWRN U.S. BY TONIGHT WITH DOWNSTREAM
RIDGING OVER THE SRN HIGH PLAINS.
...ERN OK/AR/NRN MS/WRN TN...
REF MCD 1074
HAVE UPGRADED AREA IN ADVANCE OF THE SEVERE MCS/DERECHO OVER NERN OK
TO MDT RISK AS THE COMBINATION OF 40-50KT OF SHEAR COUPLED WITH
DEVELOPMENT OF VERY TO EXTREMELY UNSTABLE AIRMASS DOWNSTREAM ACROSS
LOWER MS RIVER VALLEY EXPECTED TO RAPIDLY INCREASE THE DAMAGING WIND
POTENTIAL ALONG WITH THE ONGOING VERY LARGE HAIL THREAT. WITH
DEWPOINTS AOA 70F...SURFACE TEMPERATURES WELL INTO THE 80S...AND
STEEP MID LEVEL LAPSE RATES...MLCAPES AOA 3500 J/KG... A SWATH OF
POSSIBLY SIGNIFICANT DAMAGING WINDS WILL TRACK EWD ACROSS NRN HALF
OF AR INTO WRN TN/NRN MS BY LATER THIS AFTERNOON.
...CAROLINAS/GA/AL...
FARTHER EAST...SCATTERED THUNDERSTORMS WILL FORM THIS AFTERNOON FROM
EAST TN/AL EASTWARD INTO THE CAROLINAS. SUFFICIENT VERTICAL SHEAR
WILL BE PRESENT FOR A FEW SEVERE STORMS...ALBEIT LESS ORGANIZED THAN
FARTHER WEST. LATE TONIGHT...SOME POTENTIAL EXISTS FOR LONG-LIVED
MCS MOVING INTO THIS REGION FROM THE WEST.
...OK/TX ALONG AND JUST E OF DRYLINE...
AN EXTREMELY UNSTABLE AIRMASS IS EXPECTED TO DEVELOP THIS AFTERNOON
ALONG AND EAST OF THE SURFACE DRYLINE ACROSS CENTRAL/EASTERN OK AND
NORTH CENTRAL TX. FORECAST SOUNDINGS SUGGEST A WEAK CAPPING
INVERSION WILL SUPPRESS CONVECTION FOR MOST OF THE DAY AS HEIGHTS
GRADUALLY RISE IN ADVANCE OF THE RIDGING.
HOWEVER...ENHANCED CONVERGENCE ALONG THE REMNANT OUTFLOW BOUNDARY
FROM THIS MORNINGS STORMS ACROSS NORTHERN OK MAY HELP TO INITIATE
ISOLATED STORMS. ALSO...MOST MODELS SHOW ISOLATED CELLS FORMING
DURING THE HEAT OF THE DAY OVER NORTH CENTRAL AND NORTHEAST TX. ANY
STORM THAT FORMS IN THIS ENVIRONMENT WILL HAVE A CONDITIONAL RISK OF
BECOMING A SUPERCELL AND WILL POSE A RISK OF VERY LARGE HAIL AND
DAMAGING WINDS.
HAVE EXTENDED THE THREAT OF AT LEAST ISOLATED INITIATION INTO SWRN
TX GIVEN THE EXPECTED EXTREMELY UNSTABLE AIR MASS THAT IS EXPECTED E
OF DRY LINE. ANY STORM THAT IS ABLE TO OVERCOME THE WEAK CINH BY
LATER THIS AFTERNOON WILL QUICKLY BECOME SEVERE/SUPERCELL WITH
POTENTIAL FOR VERY LARGE HAIL.
..HALES/SMITH.. 06/12/2009
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