SWODY1
SPC AC 110548
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1248 AM CDT FRI MAY 11 2007
VALID 111200Z - 121200Z
..NO SVR TSTM AREAS FORECAST...
..SYNOPSIS...
STRONGER WLYS SHOULD EXTEND GENERALLY W-E ALONG THE U.S./CANADIAN
BORDER EARLY IN THE PERIOD...BUT SHOULD AMPLIFY WITH TIME ACROSS THE
NWRN AND N CENTRAL CONUS AS ERN PACIFIC TROUGH APPROACHES THE W
COAST AND DOWNSTREAM RIDGE AMPLIFIES. MEANWHILE...WEAK CUT-OFF LOW
SHOULD DRIFT SLOWLY ESEWD FROM E TX INTO THE NWRN GULF.
AT THE SURFACE...PATTERN WILL REMAIN GENERALLY WEAK. A BAROCLINIC
ZONE IS FORECAST TO EXTEND FROM NEW ENGLAND WSWWD ACROSS THE OH
VALLEY STATES AND THEN WNWWD ACROSS THE NRN PLAINS AND INTO THE NRN
ROCKIES DURING THE AFTERNOON/EARLY EVENING.
..LOWER MS VALLEY AND VICINITY...
GENERALLY-WEAK FLOW ALOFT BUT MOIST/UNSTABLE AIRMASS IS FORECAST
DURING THE AFTERNOON ACROSS A LARGE PORTION OF THE LOWER MS VALLEY
AND VICINITY...AS UPPER LOW DRIFTS ESEWD ACROSS E TX INTO SRN LA/THE
NWRN GULF. DESPITE THE LACK OF SHEAR...THERMODYNAMIC ENVIRONMENT
WILL BE SUPPORTIVE OF PULSE-TYPE SEVERE STORMS...AND ASSOCIATED
THREAT FOR LOCALLY-STRONG WIND GUSTS AND MARGINAL HAIL FROM
AFTERNOON THROUGH EARLY EVENING.
..PARTS OF THE NWRN CONUS/NRN ROCKIES...
MODERATELY-STRONG BELT OF ANTICYCLONIC FLOW ALOFT WILL PERSIST
ACROSS THE NWRN CONUS THIS PERIOD...DOWNSTREAM OF ERN PACIFIC
TROUGH/AROUND NRN PERIPHERY OF UPPER RIDGE. THOUGH APPARENT LACK OF
A WELL-DEFINED UPPER FEATURE SUGGESTS SYNOPTIC-SCALE
SUBSIDENCE...ISOLATED/PRIMARILY TERRAIN-INDUCED STORM DEVELOPMENT
WILL BE POSSIBLE AS AIRMASS BECOMES MARGINALLY-UNSTABLE DURING THE
AFTERNOON. GIVEN STRENGTH OF FLOW ALOFT...POTENTIAL EXISTS FOR ANY
STORMS WHICH DO DEVELOP TO INTENSIFY/BECOME SEVERE. GREATEST THREAT
APPEARS TO EXIST FROM PORTIONS OF ID EWD ACROSS CENTRAL AND SRN
PARTS OF MT DURING THE AFTERNOON/EVENING.
..SD/NRN NEB...
MID-LEVEL VORT MAX/JET STREAK IS FORECAST CROSS THE NRN PLAINS THIS
AFTERNOON...WITHIN BELT OF ENHANCED FLOW ON NRN PERIPHERY OF THE
RIDGE.
DESPITE LIMITED BOUNDARY-LAYER MOISTURE...STEEP MID-LEVEL LAPSE
RATES AND DAYTIME HEATING SHOULD RESULT IN AROUND 1000 J/KG
MIXED-LAYER CAPE ACROSS PORTIONS OF SD AND VICINITY. WITH WEAK LOW
FORECAST TO DEVELOP OVER SWRN SD AS WEAK UPPER FEATURE PASSES TO THE
N...ENHANCED LOW-LEVEL UVV MAY RESULT IN ISOLATED STORM DEVELOPMENT
BY LATE AFTERNOON. THOUGH STORM COVERAGE WILL LIKELY REMAIN
LIMITED...ANY STORMS WHICH DO DEVELOP WILL LIKELY INTENSIFY -- AIDED
BY AMPLE SHEAR/FAVORABLY VEERING WINDS WITH HEIGHT.
THEREFORE...WILL MAINTAIN 5% PROBABILITY FOR LOCALLY-DAMAGING WINDS
AND HAIL ACROSS THIS REGION.
.GOSS.. 05/11/2007
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