SWODY1
SPC AC 121621
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1121 AM CDT TUE AUG 12 2008
VALID 121630Z - 131200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE CENTRAL AND EASTERN
GULF COASTAL STATES...
...THERE IS A SLGT RISK OF SVR TSTMS IN SWRN SD AND WRN NEB...
...SYNOPSIS...
STRENGTHENING NWLY FLOW ALOFT...FROM THE NRN ROCKIES SEWD INTO THE
MID MS VALLEY...WILL RESULT IN LONGWAVE TROUGH TO GRADUALLY AMPLIFY
EAST OF THE MS RIVER. SHORTWAVE TROUGH MOVING SLOWLY EWD THROUGH NRN
LA THIS MORNING WILL GRADUALLY PHASE WITH THE UPPER
TROUGH...RESULTING IN STRENGTHENING WIND FIELDS ACROSS THE CENTRAL
AND EASTERN GULF COASTAL STATES LATER TODAY AND TONIGHT. IN
ASSOCIATION WITH THE UPPER TROUGH...A WEAK SURFACE LOW...LOCATED
NEAR SHV...IS EXPECTED TO SHIFT EWD INTO WRN GA...NEAR/ALONG A
REMNANT WARM FRONT EXTENDING FROM SRN AR EWD INTO CENTRAL GA.
ELSEWHERE...A SEWD MOVING WEAK COLD FRONT FROM THE UPPER MS VALLEY
INTO THE CENTRAL PLAINS SHOULD GRADUALLY WEAKEN AS THE UPPER TROUGH
DEEPENS IN THE EAST...WHILE A WEAK LEE TROUGH LINGERS OVER THE
CENTRAL HIGH PLAINS.
...ERN TX/LA EWD TO GA/FL PANHANDLE...
DEEP VERTICAL MOISTURE PROFILES AND UNCAPPED ENVIRONMENT WILL BE
EXTREMELY FAVORABLE FOR NUMEROUS THUNDERSTORMS AND HEAVY RAINS.
HOWEVER...COMBINATION OF ANOMALOUS UPPER AIR PATTERN FOR AUGUST AND
RELATIVELY STRONG ENVIRONMENTAL WINDS WILL RESULT IN A THREAT FOR A
FEW SEVERE STORMS...AND EVEN TORNADOES...LATER TODAY AND TONIGHT.
THE LIMITING FACTORS FOR SEVERE STORMS WILL BE WIDESPREAD PCPN...AS
CURRENTLY ONGOING FROM ERN TX EWD ACROSS MUCH OF MS/AL AND THE FL
PANHANDLE ...WEAK HEATING AND POOR MID LEVEL LAPSE RATES. BUT...AS
THE SURFACE LOW BECOMES BETTER ORGANIZED ALONG SURFACE BOUNDARY
LATER TODAY AND TONIGHT...AND LOW/DEEP LAYER SHEAR INCREASES...THE
ENVIRONMENT WILL SUPPORT SUPERCELLS. THE MOST LIKELY AREA FOR
SUPERCELL DEVELOPMENT WILL BE NEAR AND EAST OF THE SHORTWAVE
TROUGH/SURFACE WAVE...WHERE LOW/DEEP LEVEL SHEAR WILL BE THE
GREATEST ALONG WITH MID/UPPER 70S DEWPOINTS. WITH ANY SUPERCELLS
THAT DEVELOP...THE COMBINATION OF THE RICH BOUNDARY LAYER MOISTURE
AND 20-30 KT LOW LEVEL SHEAR COULD SUPPORT A FEW TORNADOES.
INCREASING WLY FLOW ALOFT...SOUTH OF SURFACE WAVE...MAY ALSO FAVOR A
FEW BOWING STRUCTURES AND POSSIBLE WIND DAMAGE.
...CENTRL HIGH PLAINS...
HEATING AND A WEAK SHORTWAVE TROUGH MOVING SEWD THROUGH WY ARE
EXPECTED TO RESULT IN WIDELY SCATTERED THUNDERSTORMS ALONG THE LEE
TROUGH FROM WRN SD SWD INTO WRN KS. ALTHOUGH LOW-LVL WINDS WILL BE
WEAK...30-40 KT WNWLY FLOW ON NRN PERIPHERY OF UPPER RIDGE WILL
YIELD AMPLE SHEAR FOR ORGANIZED STORMS AND POSSIBLY A FEW
SUPERCELLS. THESE STORMS WOULD YIELD SEVERE HAIL AND DAMAGING
WINDS...GIVEN MODERATE INSTABILITY AND STEEP MID/LOW LEVEL LAPSE
RATES. THESE STORMS MAY ORGANIZE INTO A SSEWD MOVING CLUSTER AND
PERSIST INTO THE EVENING HOURS.
...WRN/NRN MO NWD TO SERN MN...
AS CLOUDS CONTINUE TO CLEAR FROM THE WEST...SURFACE HEATING ALONG
WEAKENING COLD FRONT SHOULD SUPPORT MODEST DESTABILIZATION... SBCAPE
TO 1500 J/KG...BY LATE IN THE DAY. ALTHOUGH 30 KT DEEP NNWLY SHEAR
WILL BE SUFFICIENT FOR ORGANIZED STORMS...WEAKENING UVV/FRONTAL
CONVERGENCE SHOULD LIMIT COVERAGE OF STORMS. NEVERTHELESS...ANY
STORMS THAT FORM WILL BE CAPABLE OF MARGINALLY SEVERE WINDS/HAIL FOR
A BRIEF PERIOD OF TIME LATE TODAY.
..IMY/GRAMS.. 08/12/2008
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