DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 290546
SWODY1
SPC AC 290543

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1243 AM CDT WED AUG 29 2012

VALID 291200Z - 301200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF THE CENTRAL
GULF COAST...

...SYNOPSIS...
HURRICANE ISAAC IS FORECAST TO MOVE NWWD INTO CENTRAL LA BY 30/12Z
AND GRADUALLY WEAKEN TO A MINIMAL TROPICAL STORM BY THAT TIME.

AN UPPER TROUGH OVER THE NRN ROCKIES WILL LIFT NEWD INTO SRN CANADA
AND AN ASSOCIATED COLD FRONT WILL ENTER THE NRN PLAINS. A BROAD
UPPER TROUGH OVER NEW ENGLAND WILL GRADUALLY SHIFT EWD WHILE UPPER
LEVEL HIGH PRESSURE REMAINS IN PLACE FROM THE CENTRAL ROCKIES EWD
INTO THE CENTRAL PLAINS/MIDDLE MS VALLEY.

...CENTRAL GULF COAST...
HURRICANE ISAAC IS FORECAST TO MOVE NWWD AND BE CENTERED OVER
CENTRAL LA BY 30/12Z. THE SLOW MOVEMENT WILL ALLOW FOR A PROLONGED
FLOW OF VERY MOIST AIR/LOW LCLS TO PERSIST OVER THE CENTRAL GULF
COASTAL REGION. BASED ON THE FORECAST INTENSITY AS ISAAC MOVES
INLAND...STRONG LOW-LEVEL SHEAR AND AN ISOLATED TORNADO THREAT WILL
PERSIST ACROSS THE CENTRAL GULF COAST WEDNESDAY. POSSIBLE BREAKS IN
CLOUD COVER MAY ALLOW FOR GREATER HEATING/DESTABILIZATION ON THE
OUTER FRINGES OF THE CIRCULATION AND PERHAPS MORE PERSISTENT
SUPERCELL STRUCTURES. THE RISK OF ISOLATED TORNADOES SHOULD LESSEN
LATE IN THE PERIOD AS LOW-LEVEL WINDS AND INSTABILITY BOTH DIMINISH.


...PORTIONS OF ND/SD...
INTENSE DIABATIC HEATING WILL LIKELY RESULT IN A DEEP/WELL-MIXED
BOUNDARY LAYER ACROSS THE NRN PLAINS ON WED. A COLD FRONT ASSOCIATED
WITH THE UPPER TROUGH OVER THE CANADIAN PRAIRIE PROVINCES WILL MOVE
ACROSS THE REGION WED AFTERNOON/EVENING. ASCENT ASSOCIATED WITH THE
UPPER TROUGH AND A MID LEVEL SPEED MAX WILL LARGELY REMAIN NORTH OF
THE INTERNATIONAL BORDER. IN ADDITION...VERY WARM MID-LEVEL
TEMPERATURES SHOULD EFFECTIVELY PREVENT TSTM DEVELOPMENT UNTIL LATE
IN THE DAY. A FEW HIGH-BASED TSTMS MAY DEVELOP LATE NEAR THE
FRONT...AS SUGGESTED BY THE NSSL WRF-ARW...AND THE THERMODYNAMIC
ENVIRONMENT WILL FAVOR ISOLATED STRONG WIND GUSTS.

..BUNTING/ROGERS.. 08/29/2012

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