SWODY1
SPC AC 101622
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1122 AM CDT THU MAY 10 2007
VALID 101630Z - 111200Z
..THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF PA/NY AND WESTERN
NEW ENGLAND...
..THERE IS A SLGT RISK OF SVR TSTMS EASTERN ORE INTO SOUTHERN MT...
..THERE IS A SLGT RISK OF SVR TSTMS CENTRAL AND SOUTH TEXAS...
..NERN U.S...
UPR LOW WRN NY WILL MOVE SLOWLY EWD AND GRADUALLY OPEN INTO A TROUGH
REACHING NEW ENGLAND BY 12Z FRI. AIR MASS IN ADVANCE OF FRONTAL
ZONE STRETCHING FROM ERN LAKE ONTARIO SWWD INTO ERN OH CHARACTERIZED
BY RELATIVELY STEEP LAPSE RATES WITH SBCAPES UPWARDS TO 1500 J/KG
ONCE CONVECTIVE TEMPERATURES OF LOW 80S ARE REACHED. INITIALLY
SHEAR IN THIS WARM SECTOR IS WEAK AS REFLECTED BY 12Z ALB SOUNDING.
HOWEVER AS UPR LOW MOVES EWD MODEL FORECAST SOUNDINGS SUGGEST DEEP
LAYER SHEAR WILL INCREASE TO NEAR 30KT BY AFTERNOON. EXPECT SURFACE
BASED STORMS TO DEVELOP BY EARLY AFTERNOON ALONG/AHEAD OF FRONTAL
ZONE WITH PRIMARY SEVERE THREAT BEING LARGE HAIL GIVEN FAVORABLY LOW
WET BULB ZERO HEIGHTS FROM 8-9K FEET. LOCALIZED DOWNBURSTS ALSO
LIKELY ASSOCIATED WITH STRONGER UPDRAFTS...HOWEVER OVERALL WEAK
SHEAR PRECLUDES AN ORGANIZED WIND THREAT. SEVERE THREAT WILL
DIMINISH BY EVENING WITH LOSS OF HEATING.
..INTERIOR PAC NW INTO SRN MT...
MDT WSWLY FLOW WILL PERSIST FROM PAC NW EWD ACROSS NRN ROCKIES AS
MID LEVEL WIND MAX NOTED ON WATER VAPOR IMAGERY NOW WRN OREGON
MOVES ACROSS NRN ROCKIES BY THIS EVENING. MID LEVEL LAPSE RATES
FROM 7.5-8 C/KM IN PLACE VICINITY AND TO S OF STALLED FRONTAL ZONE
WHICH STRETCHES FROM SCENTRAL MT TO CENTRAL ID AND THEN ACROSS NRN
OR. SUFFICIENT MOISTURE WITH PW'S TO .7 INCHES COUPLED WITH STRONG
DAYTIME HEATING TO RAISE SBCAPES BY MID AFTERNOON TO AROUND 1000
J/KG FROM NERN OR TO SWRN MT. SCATTERED SURFACE BASED THUNDERSTORMS
WILL DEVELOP OVER HIGHER TERRAIN BY MID AFTERNOON ALONG AND S OF
STALLED FRONTAL ZONE. PRIMARY SEVERE THREAT WILL BE MARGINALLY
SEVERE HAIL AND DOWNBURST WINDS FROM RELATIVELY HIGH BASED STORMS.
AS UPPER WIND MAX SHIFTS EWD ACROSS MT THIS EVENING...STORMS COULD
DEVELOP INTO SHORT LINES SEGMENTS/BOWS AND INCREASE WIND DAMAGE
THREAT ACROSS LOWER ELEVATIONS OF SRN MT.
..SRN TEXAS...
INITIALLY INSTABILITY IS SOMEWHAT LIMITED AHEAD OF THE UPPER LOW NOW
LOCATED OVER NWRN TX. LOW EXPECTED TO CONTINUE SEWD INTO SERN TX
TONIGHT. LOW LEVEL SWLY FLOW WHILE GENERALLY LESS THAN 20KT ACROSS S
TX WILL NEVERTHELESS TRANSPORT MOISTURE NEWD WHICH COMBINED WITH
STRONG HEATING LEAD TO GOOD DESTABILIZATION AHEAD OF LOW THIS
AFTERNOON. BY MID AFTERNOON MLCAPES WILL RANGE DOWNWARD FROM AROUND
2000 J/KG CRP CWA TO AROUND 1000 J/KG SERN TX. WHILE LOW LEVEL
SHEAR WILL REMAIN WEAK AHEAD OF UPPER LOW...SFC-6KM SHEAR WILL
INCREASE TO 30-40KT IN ADVANCE OF UPPER LOW SUPPORTING BOTH CLUSTERS
AND POSSIBLY SUPERCELLS. PRIMARY THREAT WILL BE LARGE HAIL AND
DOWNBURSTS WITH GREATER POTENTIAL WITH ANY SUPERCELL THAT CAN
DEVELOP.
.HALES/CROSBIE.. 05/10/2007
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