SWODY1
SPC AC 050558
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1258 AM CDT MON OCT 05 2009
VALID 051200Z - 061200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
A SPLIT FLOW REGIME IS EXPECTED TO DEVELOP OVER THE WESTERN HALF OF
THE CONUS THROUGH THE PERIOD. THE BRUNT OF THE WESTERN STATES
TROUGH...CURRENTLY CENTERED OVER THE GREAT BASIN...IS EXPECTED TO
SHIFT NORTHEASTWARD OVER THE NORTH CENTRAL PORTIONS OF THE
ROCKIES/PLAINS...AHEAD OF A DEEPENING SECONDARY UPPER LOW OVER
NORTHERN CA. AS THIS OCCURS...LEE SIDE CYCLOGENESIS IS ANTICIPATED
ACROSS THE CENTRAL HIGH PLAINS...WITH A LATTER PERIOD EAST-SOUTHEAST
SURGING COLD FRONT ACROSS THE PLAINS. ELSEWHERE...OTHER
SHOWERS/TSTMS WILL REMAIN COMMON ACROSS THE EAST-CENTRAL GULF COAST
STATES IN VICINITY OF A PERSISTENT WEST-EAST FRONTAL BOUNDARY. OTHER
TSTMS WILL BE POSSIBLE OVER THE LOWER GREAT LAKES.
...CENTRAL/SOUTHERN PLAINS...
AS THE PRIMARY UPPER TROUGH SHIFTS NORTHEASTWARD OVER THE NORTH
CENTRAL ROCKIES/HIGH PLAINS...A STRONG MID/UPPER JET WITH
50-70/100-140 KT AT 500 MB/250 MB RESPECTIVELY WILL OVERSPREAD THE
SOUTHERN ROCKIES/CENTRAL PLAINS LATER TODAY. AS LEE SIDE
CYCLOGENESIS OCCURS ACROSS THE HIGH PLAINS...A MOISTURE-RICH AIRMASS
/70F SURFACE DEWPOINTS/ WILL GENERALLY BE CONFINED TO JUST PORTIONS
OF SOUTHWEST/WEST CENTRAL TX...WITH SURFACE BASED TSTM DEVELOPMENT
POSSIBLE ACROSS THIS REGION FROM MID/LATE AFTERNOON INTO EARLY
EVENING. IN SPITE OF A RATHER MOIST AIRMASS AND AMPLE POTENTIAL
INSTABILITY ACROSS THIS PART OF TX...CONCERNS REGARDING STORM
COVERAGE/VIGOR...OWING TO MODEST WARM SECTOR FORCING AT THAT LOW
LATITUDE AND WARM THERMAL PROFILES ALOFT /-5C AT 500 MB/...PRECLUDE
A CATEGORICAL SLIGHT RISK AT THIS TIME. FARTHER NORTH...LIMITED
MOISTURE AND A STRONG ELEVATED MIXED LAYER SHOULD OTHERWISE INHIBIT
SURFACE BASED DEEP CONVECTION ACROSS MUCH OF THE CENTRAL/SOUTHERN
PLAINS IN VICINITY OF A SHARPENING DRY LINE/LEE TROUGH. ONE
EXCEPTION DIURNALLY WILL BE THE DEVELOPMENT OF MARGINALLY
UNSTABLE/LOW TOPPED CONVECTIVE THERMODYNAMIC PROFILES ACROSS THE
CENTRAL HIGH PLAINS IN VICINITY OF THE SURFACE LEE TROUGH...WHICH
MAY BE CONDUCIVE FOR SOME HAIL ACROSS PORTIONS OF WESTERN KS/FAR
EASTERN CO AND PERHAPS WESTERN NEB UNTIL AROUND SUNSET.
LATER TONIGHT...A CONSIDERABLY STRENGTHENING LOW LEVEL JET /40-50
KT/ ACROSS THE SOUTH CENTRAL PLAINS LATE THIS
EVENING/OVERNIGHT...AND ASSOCIATED MOISTURE TRANSPORT ABOVE A
COOL/STABLE BOUNDARY LAYER...WILL LIKELY CONTRIBUTE TO INCREASING
ELEVATED TSTM COVERAGE NOCTURNALLY ACROSS MUCH OF THE SOUTH CENTRAL
PLAINS AND LOWER/MIDDLE MO RIVER VALLEY. SUFFICIENT ELEVATED
BUOYANCY WILL LIKELY COINCIDE WITH AMPLE SHEAR THROUGH THE CLOUD
BEARING LAYER TO SUPPORT AT LEAST SOME RISK FOR ISOLATED SEVERE HAIL
TONIGHT.
..GUYER/GARNER.. 10/05/2009
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