SWODY1
SPC AC 071940
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0140 PM CST SAT JAN 07 2012
VALID 072000Z - 081200Z
...NO SVR TSTM AREAS FORECAST...
...LOWER MS/TN VALLEYS REGION...
GREATEST COVERAGE OF ADDITIONAL TSTM DEVELOPMENT THIS AFTERNOON AND
EARLY EVENING SHOULD BE LOCATED ACROSS NRN MS/AL INTO NWRN GA.
FORCING FOR ASCENT ATTENDANT TO A MIDLEVEL DISTURBANCE...NOW MOVING
EWD THROUGH NRN MS...WILL SUPPORT THIS ACTIVITY...WHILE EFFECTIVE
BULK SHEAR OF 30-35 KT SHOULD AID IN MAINTAINING SOME ORGANIZATION.
HOWEVER...OVERALL WEAK INSTABILITY/MIDLEVEL LAPSE RATES ARE EXPECTED
TO PRECLUDE A SEVERE WEATHER THREAT. ADDITIONAL TSTMS REMAIN
POSSIBLE SWWD THROUGH THE LOWER MS VALLEY AND CENTRAL GULF
COAST...THOUGH WEAK INSTABILITY...HERE TOO...WILL TEND TO LIMIT
OVERALL COVERAGE.
..PETERS.. 01/07/2012
.PREV DISCUSSION... /ISSUED 1024 AM CST SAT JAN 07 2012/
...LOWER MS/TN VALLEY REGION THROUGH TONIGHT...
A NRN STREAM SHORTWAVE TROUGH WILL CONTINUE EWD FROM THE GREAT LAKES
TO NEW ENGLAND...AS AN ASSOCIATED COLD FRONT MOVES SLOWLY SEWD
ACROSS SRN AR...NW MS...WRN/MIDDLE TN...AND KY. THE FRONT EXTENDS
WWD TO A WEAK LOW IN NE TX THAT IS BEING MAINTAINED BY THE APPROACH
OF A WEAK EMBEDDED SHORTWAVE TROUGH MOVING EWD OVER SE OK/NE TX.
PHASING OF THE SE OK TROUGH WITH THE RIGHT ENTRANCE REGION OF THE
GREAT LAKES UPPER JET HAS SUPPORTED A BAND OF ASCENT AND ELEVATED
THUNDERSTORMS OVER NRN MS THIS MORNING. REGIONAL 12Z SOUNDINGS
SHOWED MUCAPE OF 250-750 J/KG BASED IN THE 900-850 MB LAYER...AND
THE RISK FOR A FEW THUNDERSTORMS WILL PERSIST THROUGH MIDDAY-EARLY
AFTERNOON...UNTIL THE BAND OF ASCENT BEGINS TO PROGRESS E OF THE
UNSTABLE WARM SECTOR.
MEANWHILE...DAYTIME HEATING/MIXING WILL ESTABLISH THE SURFACE WARM
SECTOR FROM EXTREME SE TX ACROSS LA/MS. THE MAGNITUDE OF WARM
SECTOR INSTABILITY WILL BE LIMITED BY MIDLEVEL LAPSE RATES OF ONLY
6-6.5 C/KM...BUT CONVECTIVE INHIBITION WILL BE WEAK ONCE SURFACE
TEMPERATURES REACH 65-70 F. THE COMBINATION OF A MINIMAL CAP AND
SOMEWHAT NEBULOUS FORCING FOR ASCENT WILL SUPPORT ISOLATED-WIDELY
SCATTERED AFTERNOON SHOWERS/TSTMS. DEEP-LAYER VERTICAL SHEAR WILL
BE MARGINALLY FAVORABLE FOR PERSISTENT STORMS...BUT THE POOR LAPSE
RATES AND RELATIVELY WEAK LOW-LEVEL SHEAR SUGGEST THAT SEVERE STORMS
ARE UNLIKELY.
...UT/WRN CO THIS AFTERNOON...
A PRONOUNCED SHORTWAVE TROUGH IS DIGGING SSEWD FROM UT/NV TOWARD AZ.
ASCENT DOWNSTREAM FROM THIS WAVE AND STEEP LAPSE RATES WILL PROMOTE
THE DEVELOPMENT OF SHALLOW CONVECTION. HOWEVER...LIMITED
MOISTURE/BUOYANCY SUGGEST THAT LITTLE IF ANY LIGHTNING WILL OCCUR
WITH THIS CONVECTION ACROSS UT/WRN CO.
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