SPC AC 140100
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0800 PM CDT TUE JUL 13 2010
VALID 140100Z - 141200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF THE DAKOTAS INTO
MN...
...THERE IS A SLGT RISK OF SVR TSTMS FROM PART OF ERN GA/CAROLINAS
INTO SRN/CENTRAL VA...
...DAKOTAS/MN...
MINOR CHANGES HAVE BEEN MADE TO THE DAY 1 OUTLOOK FOR THE
EVENING/OVERNIGHT PERIOD. EVENTUAL DECOUPLING OF THE BOUNDARY LAYER
TONIGHT SHOULD RESULT IN A GREATER POTENTIAL FOR STORMS TO BE
ELEVATED. THUS...THE TORNADO/DAMAGING WIND PROBABILITIES HAVE BEEN
REDUCED SOME...BUT ARE AT VALUES THAT CONTINUE SO SUPPORT A
CATEGORICAL SLIGHT RISK. STRONG CAPPING WITH SWD EXTENT IS EXPECTED
TO LIMIT THE SEVERE WEATHER THREAT INTO NWRN IA/FAR SERN SD...AND
THUS HAVE SHIFTED THE SLIGHT RISK NWD SOME.
THE GREATEST TORNADO THREAT SHOULD BE OVER ERN ND/NWRN MN INTO THE
MID EVENING WHERE STRONG EFFECTIVE BULK SHEAR /50+ KT/ VECTORS
ORIENTED PERPENDICULAR TO A N-S WIND SHIFT OVER THE ERN DAKOTAS
MAINTAINS A SUPERCELL POTENTIAL. IN ADDITION...RESIDUAL MODERATE TO
VERY STRONG INSTABILITY COMBINED WITH STEEP LAPSE RATES AND BACKED
SURFACE WINDS ENHANCES THE TORNADO THREAT AND POTENTIAL FOR VERY
LARGE HAIL.
EARLY EVENING WIND PROFILERS/WSR-88D VADS SHOWED THE LLJ FROM MID MO
VALLEY INTO SWRN MN BEGINNING TO VEER TO SWLY AND STRENGTHEN.
FURTHER STRENGTHENING IS EXPECTED INTO THE OVERNIGHT PERIOD
SUPPORTING STRONG LOW LEVEL WAA. THIS SUGGESTS EVENTUAL UPSCALE
GROWTH OF ERN ND/NWRN MN TSTMS AND POTENTIAL FOR STORMS TO DEVELOP
SEWD INTO CENTRAL MN WITH ACTIVITY SPREADING EWD ACROSS THE NRN HALF
OF MN AS THE LLJ FEEDS VERY STRONG INSTABILITY INTO MN TONIGHT.
STRONG DEEP LAYER SHEAR AND STEEP MIDLEVEL LAPSE RATES WILL MAINTAIN
A THREAT FOR HAIL AND STRONG WIND GUSTS WITH THIS POTENTIAL MCS.
MEANWHILE...STRONG FORCING FOR ASCENT ATTENDANT TO A SHORTWAVE
TROUGH SPREADING EWD FROM THE NRN ROCKIES/HIGH PLAINS AND ASCENT
WITHIN EXIT REGION OF ACCOMPANYING STRONG WSWLY MID-UPPER LEVEL JETS
WILLS SPREAD INTO THE DAKOTAS TONIGHT. A COLD FRONT IS EXPECTED TO
STRENGTHEN AS IT ADVANCES EWD INTO THE DAKOTAS WITH TSTMS DEVELOPING
ALONG THIS BOUNDARY AND IN THE POST-FRONTAL ENVIRONMENT. MODERATE
ELEVATED INSTABILITY... STRONG EFFECTIVE BULK SHEAR AND STRONG
FORCING ALOFT ARE EXPECTED TO SUPPORT A THREAT FOR SEVERE STORMS
SPREADING ACROSS ND AND CENTRAL/NRN SD INTO WRN MN.
...ERN GA/CAROLINAS TO MID ATLANTIC STATES...
FORCING FOR ASCENT ATTENDANT TO A COUPLE OF WELL-DEFINED MIDLEVEL
SHORTWAVE TROUGHS MOVING ENEWD FROM THE CENTRAL AND SRN APPALACHIANS
WILL CONTINUE TO SUPPORT TSTM DEVELOPMENT MAINLY IN LEE OF THE
APPALACHIANS FROM THE CAROLINAS TO THE MID ATLANTIC STATES THIS
EVENING. ERN EXTENT OF THE SEVERE WEATHER THREAT SHOULD BE
DELINEATED BY THE INLAND INTRUSION OF THE SEA BREEZE. SEVERE WEATHER
THREAT SHOULD DIMINISH LATER THIS EVENING AS INSTABILITY DIMINISHES
AND SBCINH INCREASES.
..PETERS.. 07/14/2010
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0600Z
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