SWODY2
SPC AC 191716
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1216 PM CDT SAT APR 19 2008
VALID 201200Z - 211200Z
...NO SVR TSTM AREAS FORECAST...
...MID ATLANTIC...
A CLOSED-OFF UPPER-LEVEL LOW OVER THE OH VALLEY TONIGHT WILL MOVE
EWD INTO THE CNTRL APPALACHIAN MTNS SUNDAY. AT THE SFC...A TROUGH
AND COLD FRONT WILL MOVE EWD INTO VA AND THE CAROLINAS BY SUNDAY
AFTERNOON. ABUNDANT CLOUD COVER AND SCATTERED THUNDERSTORM ACTIVITY
SHOULD BE ONGOING AT THE BEGINNING OF THE PERIOD AND THIS SHOULD
HAMPER DESTABILIZATION ACROSS THE REGION. IN SPITE OF WEAK
INSTABILITY...SFC DEWPOINTS IN THE LOWER 60S F AND LIMITED SFC
HEATING SHOULD BE ENOUGH TO GRADUALLY INCREASE STORM INTENSITY BY
EARLY SUNDAY AFTERNOON. STRONG FORCING AND COLD AIR ALOFT ASSOCIATED
WITH THE UPPER-LEVEL LOW MAY SUPPORT A HAIL THREAT NEAR PEAK
HEATING. HOWEVER...FORECAST SOUNDINGS VALID AT 21Z ACROSS
MID-ATLANTIC SHOW LOW-END MODERATE VERTICAL SHEAR...0-6 KM SHEAR IN
THE 25 TO 35 KT RANGE. THIS WILL LIKELY KEEP THE THUNDERSTORM
ACTIVITY UNORGANIZED AND ANY SEVERE THREAT SHOULD REMAIN MARGINAL
ACROSS THE REGION.
...NRN PLAINS...
AN UPPER-LEVEL TROUGH OVER THE WEST COAST TONIGHT IS FORECAST TO
SWING ENEWD INTO THE NRN ROCKIES SUNDAY. THIS WILL INCREASE
LARGE-SCALE ASCENT EWD ACROSS THE NRN PLAINS DURING THE DAY 2
PERIOD. ALTHOUGH...FORECAST SOUNDINGS SHOW A STRONG CAPPING
INVERSION IN PLACE SUNDAY AFTERNOON...THE CAP SHOULD WEAKEN BY EARLY
EVENING AS LIFT INCREASES AND LOW-LEVEL CONVERGENCE BECOMES ENHANCED
NEAR A DEVELOPING SFC LOW. THIS SHOULD ALLOW SCATTERED THUNDERSTORMS
TO DEVELOP SUNDAY EVENING IN THE WRN DAKOTAS WITH THE ACTIVITY
SPREADING ENEWD INTO THE CNTRL AND ERN DAKOTAS DURING THE LATE
EVENING AND OVERNIGHT PERIOD. STEEP LAPSE RATES AND INCREASING
VERTICAL SHEAR PROFILES IN THE EXIT REGION OF AN EJECTING MID-LEVEL
JET MAY SUPPORT A THREAT FOR HAIL WITH THE STRONGER CELLS. NONE OF
THE ACTIVITY IS EXPECTED TO BE ORGANIZED.
..BROYLES.. 04/19/2008
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