SWODY1
SPC AC 020059
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0759 PM CDT SUN MAY 01 2011
VALID 020100Z - 021200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM NERN TX...EXTREME SERN
OK...NWRN LA...MUCH OF AR TO FAR WRN TN/NWRN MS...
...CENTRAL-NERN TX TO THE LOWER OH VALLEY...
EARLY EVENING SURFACE ANALYSIS INDICATED AN AREA OF LOW PRESSURE
LOCATED OVER FAR NERN TX...WITH THIS FEATURE SITUATED ON A FRONT
WHICH WAS DRAPED FROM SRN IND SWWD THROUGH FAR WRN TN AND THEN SWWD
TO THE NERN TX LOW. A COLD FRONT TRAILED SSWWD FROM THE LOW THROUGH
EAST CENTRAL TO SOUTH CENTRAL TX AND INTO NRN MEXICO.
THE STRONGEST INSTABILITY COUPLED WITH STRONG EFFECTIVE BULK SHEAR
SUPPORTIVE FOR ORGANIZED STORMS SHOULD PERSIST FROM INVOF THE
SURFACE LOW INTO SRN AR THIS EVENING. HAIL...DAMAGING WINDS AND A
TORNADO OR TWO REMAIN POSSIBLE...WITH THE LATTER THREAT GREATEST
FROM NERN TX/SWRN AR TO EAST CENTRAL AR. THE SURFACE LOW IS
EXPECTED TO MOVE ENEWD INTO SRN AR BY LATE EVENING...SHIFTING THE
GREATER TORNADO THREAT INTO THIS PART OF AR. HOWEVER...MODELS
SUGGEST WEAKENING INSTABILITY LATER THIS EVENING INTO THE OVERNIGHT
PERIOD COMBINED WITH DECREASING DEEP LAYER SHEAR SHOULD LIMIT THE
OVERALL SEVERE WEATHER THREAT ALONG AND S OF THE BOUNDARY...
ESPECIALLY AFTER MIDNIGHT.
MEANWHILE...LOW LEVEL WAA PER SLY WINDS IMPINGING UPON THE FRONT
FROM CENTRAL TX TO THE LOWER OH VALLEY WILL SUPPORT A CONTINUATION
OF OVERRUNNING CONVECTION AND TRAINING STORMS TRACKING NEWD. STRONG
EFFECTIVE BULK SHEAR AND MODERATE INSTABILITY FROM SERN OK TO
CENTRAL/NRN AR SHOULD SUPPORT SOME SEVERE HAIL THROUGH THIS FORECAST
PERIOD. ADDITIONAL STORMS SHOULD DEVELOP LATER TONIGHT OVER CENTRAL
TX...WELL NORTH OF THE COLD FRONT...AS HEIGHTS BEGIN TO FALL AS THE
UPSTREAM TROUGH SHIFTS SLOWLY EWD. A FEW OF THESE STORMS ALSO MAY
SUPPORT ELEVATED CORES CAPABLE OF PRODUCING A THREAT FOR ISOLATED
HAIL. THOUGH...COVERAGE DOES NOT WARRANT A SLIGHT RISK INTO THIS
REGION OF CENTRAL TX.
...CENTRAL ROCKIES/NRN HIGH PLAINS...
STEEP MIDLEVEL LAPSE RATES AND CYCLONIC FLOW FROM THE NRN HIGH
PLAINS TO WRN NEB MAY SUPPORT A FEW ADDITIONAL CONVECTIVE SHOWERS
THROUGH THE EVENING. HOWEVER...DECREASING INSTABILITY DUE TO THE
LOSS OF DAYTIME HEATING IS EXPECTED TO REDUCE THE OVERALL COVERAGE
OF STRONGER UPDRAFTS. THE PROBABILITY FOR TSTMS IS EXPECTED TO BE
LESS THAN 10 PERCENT THIS FORECAST PERIOD...AND THUS NO LONGER
WARRANTS A GENERAL TSTM AREA.
..PETERS.. 05/02/2011
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