DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 060600
SWODY1
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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