SPC AC 060558

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1258 AM CDT TUE AUG 06 2013

   VALID 061200Z - 071200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE SOUTH-CENTRAL
   PLAINS/UPPER MIDWEST TO THE MIDDLE MS VALLEY...

   ...SYNOPSIS...
   A SPLIT UPPER FLOW REGIME WILL EXIST OVER THE WESTERN THIRD OF THE
   CONUS...WITH A NORTHEASTWARD MOVING UPPER LOW OVER THE SOUTHERN
   ROCKIES WHILE ANOTHER UPPER LOW SLOWLY APPROACHES NORTHERN CA.
   MEANWHILE...ON THE SOUTHERN PERIPHERY OF A CLOSED/SLOW-MOVING UPPER
   TROUGH CENTERED OVER NORTHERN PORTIONS OF MANITOBA/ONTARIO...A BELT
   OF SEASONALLY STRONG WESTERLIES WILL CONTINUE TO OVERSPREAD THE
   NORTHERN PLAINS TO THE GREAT LAKES REGION.

   ...UPPER MIDWEST/MIDDLE MO VALLEY TO SOUTH-CENTRAL PLAINS...
   A CLUSTER OF TSTMS IS EXPECTED TO BE ONGOING ACROSS PORTIONS OF THE
   MIDDLE MO VALLEY/UPPER MIDWEST AT THE BEGINNING OF THE
   PERIOD...POTENTIALLY AS FAR EAST-SOUTHEAST AS PORTIONS OF IA/PERHAPS
   MN. PENDING THE EXACT EVOLUTION/TIMING...A
   CONTINUATION/REINVIGORATION ESPECIALLY OVER THE SOUTHERNMOST
   CLUSTER/S CANNOT BE ENTIRELY DISCOUNTED DURING THE DAY INTO PORTIONS
   OF THE MIDWEST/UPPER MS VALLEY.

   OTHERWISE...THE BOUNDARY LAYER WILL GRADUALLY DESTABILIZE ACROSS THE
   MIDDLE MO VALLEY INTO THE UPPER MIDWEST/UPPER MS VALLEY ALONG/AHEAD
   OF A SOUTHEASTWARD-ADVANCING COLD FRONT...WITH AS MUCH AS 1500-3500
   J/KG OF MLCAPE POSSIBLE. THIS WILL ESPECIALLY BE THE CASE SOUTH OF
   ANY EARLY DAY MCS ACTIVITY...WITH A MORE UNCERTAIN
   CONFIDENCE/QUANTITY OF DESTABILIZATION FARTHER NORTH NEAR THE
   FRONT/AN EXPECTED SURFACE LOW IN VICINITY OF NORTH-CENTRAL
   MN/NORTHERN WI. REGARDLESS...AIDED BY FRONTAL UPLIFT/FORCING FOR
   ASCENT...SURFACE BASED TSTMS ARE LIKELY TO INCREASE THROUGH MID/LATE
   AFTERNOON...POTENTIALLY ACROSS PORTIONS OF MN/IA INTO
   EASTERN/SOUTHERN NEB. MORE THAN ADEQUATE VERTICAL SHEAR WILL EXIST
   FOR ORGANIZED STORMS INCLUDING SUPERCELLS...CAPABLE OF SEVERE
   HAIL/DAMAGING WINDS AND PERHAPS A TORNADO. THE NATURE OF THE FORCING
   SUGGESTS THAT MULTIPLE SOUTHEASTWARD-MOVING LINE SEGMENTS/POTENTIAL
   BOWS SHOULD EVOLVE ACROSS THE UPPER MIDWEST/MS VALLEY THROUGH
   EARLY/MID EVENING...WITH AN ACCENTUATED POTENTIAL FOR DAMAGING
   WINDS.

   FARTHER SOUTHWEST...OTHER STRONG/SEVERE TSTMS SHOULD DEVELOP IN
   VICINITY OF SURFACE BOUNDARY/POST-FRONTAL UPSLOPE ACROSS THE
   SOUTH-CENTRAL HIGH PLAINS. HERE...AN UNSTABLE AIRMASS/MODEST
   VERTICAL SHEAR WILL SUPPORT STORMS /INCLUDING SOME SUPERCELLS/
   CAPABLE OF LARGE HAIL/DAMAGING WINDS. STORMS SHOULD DEVELOP/EXPAND
   EASTWARD INTO THE LOWER MO VALLEY/MIDDLE MS VALLEY TONIGHT AS LOW
   LEVEL JET AIDED ASCENT INCREASES NEAR CONSOLIDATING FRONTAL
   SEGMENTS.

   ...OZARKS/LOWER MS VALLEY TO SOUTHEAST STATES...
   MULTIPLE CLUSTERS OF TSTMS /WITH ASSOCIATED OUTFLOW AND POSSIBLE
   MCV/ MAY PERSIST AND BE ONGOING ACROSS THE REGION THIS
   MORNING...ESPECIALLY ACROSS PARTS OF THE OZARKS/MID-SOUTH. RENEWED
   DIURNALLY-INTENSIFYING STORMS...AT LEAST IN AN ISOLATED/WIDELY
   SCATTERED SENSE...SHOULD OCCUR TO THE SOUTHEAST OF THIS EARLY DAY
   ACTIVITY WHERE STRONG HEATING/DESTABILIZATION OCCURS. MULTICELLULAR
   STORMS WITHIN AN APPRECIABLY UNSTABLE/MOIST ENVIRONMENT MAY YIELD A
   THREAT FOR DOWNBURSTS CAPABLE OF LOCALIZED DAMAGING WIND GUSTS AND
   PERHAPS PULSE-TYPE HAIL.

   ..GUYER/ROGERS.. 08/06/2013

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