SWODY1
SPC AC 040600
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0100 AM CDT SUN APR 04 2010
VALID 041200Z - 051200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE LOWER MO/MIDDLE MS
RIVER VALLEYS...
...SYNOPSIS...
RELATIVELY FAST WEST-SOUTHWESTERLY MID-UPPER FLOW WILL PREVAIL
ESPECIALLY FROM MUCH OF THE WESTERN CONUS TO THE GREAT
LAKES/NORTHEAST STATES. AHEAD OF MORE SUBSTANTIAL HEIGHT FALLS/UPPER
TROUGH DEVELOPMENT OVER THE WESTERN STATES...MULTIPLE LOW AMPLITUDE
DISTURBANCES ARE EXPECTED TO CROSS THE PLAINS/UPPER MIDWEST TODAY.
OTHERWISE...ON THE WESTERN PERIPHERY OF SOUTHEAST STATES HIGH
PRESSURE...A MODIFIED GULF AIRMASS WILL RETURN NORTHWARD ACROSS TX
AND MUCH OF OK/ARKLATEX ESPECIALLY THIS AFTERNOON AND TONIGHT.
...SOUTHEAST KS/FAR NORTHEAST OK TO LOWER MO/MIDDLE MS RIVER
VALLEYS...
SUBTLY RISING UPPER HEIGHTS/RELATIVELY WEAK FORCING ON THE LARGE
SCALE IMPLIES THAT STORMS SHOULD STRUGGLE TO DEVELOP ACROSS MUCH OF
THE NORTHEAST-SOUTHWEST ORIENTED/SLOWLY E-SE ADVANCING COLD FRONT
DURING THE DAY. BUT BY LATE AFTERNOON AND ESPECIALLY EARLY
EVENING...THE COMBINATION OF AN INCREASING LOW LEVEL JET/ISENTROPIC
LIFT REGIME...AIDED BY A PASSING SPEED MAX/SHORTWAVE TROUGH OVER THE
UPPER MIDWEST...SHOULD CONTRIBUTE TO INCREASING TSTM DEVELOPMENT
ALONG THE FRONT ESPECIALLY ACROSS NORTHERN MO/NORTHERN IL...WITH
DEEP CONVECTIVE COVERAGE A LITTLE MORE UNCERTAIN WITH SOUTHWESTWARD
EXTENT ACROSS SOUTHWEST MO/SOUTHEAST KS/NORTHEAST OK.
WITH THE POSSIBILITY OF AROUND 60 F SURFACE DEWPOINTS AHEAD OF THE
FRONT AS FAR EAST AS THE MIDDLE MS RIVER VALLEY...A WEAKLY
CAPPED/MODERATELY UNSTABLE BOUNDARY LAYER...COUPLED WITH STRONG
VERTICAL SHEAR /50+ KT/ WILL BE MORE THAN ADEQUATE FOR
SUPERCELLS...WITH A RISK OF SEVERE HAIL AND PERHAPS A TORNADO OR
TWO. STORMS SHOULD TEND TO GRADUALLY CONGEAL AS THEY DEVELOP
EAST-SOUTHEASTWARD THROUGH THE EVENING HOURS...WITH SOME POTENTIAL
FOR DAMAGING WINDS AS WELL.
...AR/OZARKS THIS AFTERNOON...
UNCLEAR/CONDITIONAL SCENARIO ACROSS THE REGION TODAY AMIDST WEAK
FORCING/GRADUALLY RISING UPPER HEIGHTS...BUT ASSORTMENT OF NUMERICAL
GUIDANCE /ESPECIALLY THE 00Z GFS AND 21Z ETA-KF CONTROL/ IMPLIES
CONVECTIVE DEVELOPMENT DURING THE AFTERNOON. GIVEN THE STEADY
MOISTURE TRANSPORT/THETA-E ADVECTION...CANNOT RULE OUT TSTM
INITIATION/SOME SEVERE RISK...AS THERMODYNAMIC/SHEAR ENVIRONMENT
WOULD OTHERWISE SUPPORT SOME ORGANIZED STORMS CAPABLE OF MAINLY
HAIL/WIND.
...NORTHERN/WESTERN OK TO NORTHWEST TX LATE THIS AFTERNOON/EARLY
EVENING...
AMPLE HEATING/MODEST CONVERGENCE IN VICINITY OF SOUTHWARD SAGGING
FRONT AND/OR DRYLINE COULD SUPPORT ISOLATED STRONG/SEVERE TSTMS LATE
THIS AFTERNOON/EARLY EVENING ACROSS PORTIONS OF NORTHERN/WESTERN OK
AND PERHAPS NORTHWEST TX. SCENARIO IS RATHER CONDITIONAL GIVEN
LIMITED SUPPORT ON THE LARGE SCALE AND MODEST NEAR-SURFACE
CONVERGENCE...BUT AN INCREASINGLY MOIST BOUNDARY LAYER BENEATH
MODERATELY STRONG WSW FLOW ALOFT COULD SUPPORT A SUPERCELL OR TWO
WITH HAIL POSSIBLE.
..GUYER/GRAMS.. 04/04/2010
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