SWODY1
SPC AC 051629
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1129 AM CDT SAT SEP 05 2009
VALID 051630Z - 061200Z
...NO SVR TSTM AREAS FORECAST...
...SOUTHWEST TO INTERMOUNTAIN WEST...
ABUNDANT MOISTURE AND BACKGROUND ASCENT ASSOCIATED WITH THE PASSAGE
OF SEVERAL SHORT WAVE PERTURBATIONS WILL CONTINUE TO CONTRIBUTE TO
FAIRLY EXTENSIVE CONVECTION FROM LOWER CO RIVER VALLEY NWD/NEWD
ACROSS THE GREAT BASIN/INTERMOUNTAIN REGIONS TODAY. LIMITED
INHIBITION INDICATED IN MORNING SOUNDINGS ALSO SUPPORTS A GRADUAL
INCREASE IN STORM COVERAGE WITH DIURNAL HEATING CYCLE. UNLIKE RECENT
DAYS...MORNING SOUNDINGS SHOW GREATER LOW LEVEL MOISTURE AND THERE
ARE MORE ONGOING STORMS EARLY TODAY. THUS...ANY MICROBURST/WIND
DAMAGE POTENTIAL WILL LIKELY OCCUR WITH MORE PERSISTENT STORM
ACTIVITY MOVING INTO AREAS EXPERIENCING GREATER HEATING THROUGH THIS
AFTERNOON. GIVEN WEAK FLOW REGIME AND EXTENT OF ONGOING CONVECTION
AND CONVECTIVE DEBRIS...SEVERE POTENTIAL FROM WIND/HAIL APPEARS
LIMITED. HOWEVER...SLOW/ERRATIC CELL MOTIONS COULD RESULT IN LOCALLY
EXCESSIVE RAINFALL.
...ID/MT BORDER AREA...
STRONG DYNAMIC FORCING FOR ASCENT/HEIGHT FALLS WILL ACCOMPANY THE
APPROACH OF A PAC NW UPPER TROUGH ACROSS THE INTERIOR NW TODAY.
STEEPENING LAPSE RATES AND SOME MOISTENING ASSOCIATED WITH THE
APPROACH OF THIS SYSTEM COULD BOOST TSTM POTENTIAL ACROSS THE
BITTERROOT MOUNTAINS BY LATE AFTERNOON. DESPITE LACK OF GREATER LOW
LEVEL MOISTURE...IT DOES APPEAR THAT RELATIVELY HIGH-BASED
CONVECTION WILL OCCUR AMIDST INCREASING SHEAR. THIS ACTIVITY WILL BE
FURTHER FOCUSED WITHIN SURFACE PRE-FRONTAL TROUGH AND COULD POSE
SOME THREAT OF ISOLATED DAMAGING WINDS AND PERHAPS SOME HAIL.
...ELSEWHERE...
PERSISTENT WEAK ASCENT ASSOCIATED WITH SMALL-SCALE VORTEX WILL
CONTINUE TO ACT ON MOIST AND DIURNALLY WARMED AIR MASS TO PROVOKE
SHOWERS AND TSTMS FROM AR/MO EWD ACROSS THE MIDDLE MS VALLEY. WEAK
FLOW AND MARGINAL LAPSE RATES SHOULD PRECLUDE SEVERE.
THERE IS A SIGNAL IN SOME GUIDANCE INDICATING AN INCREASE IN OVERALL
STORM COVERAGE AND PERHAPS INTENSITY ACROSS THE MS DELTA REGION
THROUGH THE DAY. FORCING/FOCUS FOR THIS DEVELOPMENT APPEARS
AMBIGUOUS OTHER THAN PERHAPS AN INCREASE IN LOW LEVEL MOISTURE FLUX
INTO THE REGION AND GULF BREEZE DEVELOPMENT. WEAK FLOW BUT MORE THAN
SUFFICIENT MOISTURE AND WEAK CAP COULD LEAD TO AN INCREASING CHANCE
FOR WET MICROBURSTS THIS AFTERNOON. LIMITED FOCUS ATTM PRELUDES
TRYING TO DELINEATE A GREATER PROBABILITY AREA.
A SIMILAR ENVIRONMENT EXISTS ACROSS SRN FL. HERE...
OUTFLOW/DIFFERENTIAL HEATING FROM A PERSISTENT CLUSTER OF STORMS
OVER THE KEYS MAY INTERACT WITH GULF BREEZE BOUNDARIES TO SUPPORT AN
ISOLATED DOWNBURST WIND EVENT OVER THE NEXT SEVERAL HOURS. AGAIN THE
PROBABILITY OF THIS EVENT BASED ON DURATION/COVERAGE APPEARS QUITE
LOW BUT IS ALSO NON-ZERO.
..CARBIN/RACY.. 09/05/2009
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