DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 281627
SWODY1
SPC AC 281625

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1125 AM CDT TUE AUG 28 2012

VALID 281630Z - 291200Z

...THERE IS A SLGT RISK OF SVR TSTMS THROUGH TONIGHT ACROSS PARTS OF
THE NRN GULF COAST...

...SYNOPSIS...

LARGE-SCALE ANTICYCLONE WILL REMAIN ANCHORED OVER THE CNTRL ROCKIES
THROUGH THE D1 PERIOD...BRACKETED BY TROUGHS OVER WRN CANADA/PACIFIC
NW AND ERN CANADA/NERN STATES. WITHIN THIS BROAD-SCALE PATTERN...A
SHORTWAVE TROUGH WILL MOVE OFF THE NEW ENGLAND COAST LATER TODAY
WHILE FARTHER W...A VORTICITY MAXIMUM WEAKENS OVER THE MIDWEST.
ELSEWHERE...LATEST NHC GUIDANCE INDICATES THAT ISAAC HAS BECOME A
HURRICANE WHICH WILL MAKE LANDFALL LATE IN THE PERIOD OVER SERN
LA.

...NRN GULF COAST...

LOCALLY INTENSE DIABATIC WARMING WITHIN CLOUD BREAKS TO THE N OF CDO
ATTENDANT TO ISAAC WILL COMBINE WITH BOUNDARY LAYER DEWPOINTS IN THE
MID 70S TO SUPPORT A MODERATELY UNSTABLE AIR MASS BY AFTERNOON WITH
MLCAPE OF 1000-1500 J/KG. AS OF 1530Z...REGIONAL RADAR DATA SHOW A
PROMINENT CONVECTIVE BAND DEVELOPING FROM NEAR MOBILE SEWD TO
APPROXIMATELY 40 SSW PFN WITHIN A KINEMATIC ENVIRONMENT
CHARACTERIZED BY 0-1-KM SRH OF 200-400+ M2/S2. CONTINUED
HEATING/DESTABILIZATION SHOULD PROMOTE FURTHER INTENSIFICATION OF
ONGOING CONVECTION WITH AN INCREASED RISK FOR EMBEDDED...MINI
SUPERCELLS CAPABLE OF TORNADOES.

FOR ADDITIONAL NEAR-TERM GUIDANCE...SEE TORNADO WATCH 591.

...ERN DAKOTAS TO UPPER MS VALLEY THIS AFTERNOON INTO TONIGHT...

ELEVATED...TSTM COMPLEX HAS GRADUALLY WEAKENED THIS MORNING WITH THE
CESSATION OF THE NOCTURNAL LOW-LEVEL WIND MAXIMUM. PREVAILING WNWLY
MIDLEVEL FLOW WILL ALLOW FOR AN EML OVER NRN HIGH PLAINS TO SPREAD
EWD...RESULTING IN A STRENGTHENING CAP ACROSS THE REGION. BASED ON
LATEST MODEL GUIDANCE...IT APPEARS THAT THE GREATEST POTENTIAL FOR
ISOLATED...AFTERNOON/EVENING STORM DEVELOPMENT WILL BE OVER SERN
SD/SWRN MN/NWRN IA ON THE NRN EXTENT OF LOW-LEVEL THERMAL RIDGE AND
E OF SURFACE LOW WHERE CONVERGENCE IS ENHANCED.

GIVEN THE PRESENCE OF A VERTICALLY VEERING WIND PROFILE...40 KT OF
DEEP-LAYER SHEAR...AND A MODERATELY UNSTABLE AIR MASS...SETUP WILL
BE SUPPORTIVE OF SUPERCELL STRUCTURES CAPABLE OF HAIL AND LOCALLY
DAMAGING WIND GUSTS. ADDITIONAL...ELEVATED STORMS MAY DEVELOP LATER
TONIGHT INTO WEDNESDAY MORNING OVER SRN MN/WRN WI WITHIN
STRENGTHENING WAA/ISENTROPIC ASCENT REGIME AT TERMINUS OF NOCTURNAL
LOW-LEVEL JET.

..MEAD/GARNER.. 08/28/2012

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