DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 080555
SWODY2
SPC AC 080553

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1253 AM CDT MON APR 08 2013

VALID 091200Z - 101200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE LOWER MO VALLEY TO THE
SRN PLAINS...

...SYNOPSIS...
HIGHLY AMPLIFIED UPPER-LEVEL TROUGH OVER THE WEST SHOULD EVOLVE INTO
A FEW DISTINCT SHORTWAVE IMPULSES...TWO OF WHICH WILL BE PROMINENT
FOR AFFECTING SEVERE POTENTIAL IN THE CNTRL STATES. ONE IMPULSE
SHOULD MOVE NEWD TOWARDS THE CNTRL HIGH PLAINS/BLACK HILLS...WHILE
ANOTHER SHOULD EJECT ONTO THE SRN HIGH PLAINS TUE NIGHT. AT THE
SURFACE...A DRYLINE WILL MIX EWD INTO WRN OK AND ACROSS THE EDWARDS
PLATEAU IN TX. A SHARP COLD FRONT WILL PROGRESSIVELY OVERTAKE THE
DRYLINE...LIKELY REACHING A NERN TO S-CNTRL TX LINE BY 12Z/WED.

...LOWER MO VALLEY TO THE SRN PLAINS...
A BROAD CORRIDOR OF SEVERE TSTMS WITH ALL HAZARD TYPES POSSIBLE IS
EXPECTED TO COMMENCE TUE AFTERNOON AND CONTINUE THROUGH WED MORNING.

NCEP GUIDANCE HAS FINALLY COME INTO LINE WITH THE MORE CONSISTENT
ECMWF WITH DETAILS OVER THE SYNOPTIC PATTERN...RENDERING HIGHER
CONFIDENCE IN THE ANTICIPATED CONVECTIVE EVOLUTION. NEVERTHELESS...A
FEW LIMITING FACTORS HAVE MITIGATED A MODERATE RISK ISSUANCE ATTM. A
MODERATELY UNSTABLE AIR MASS WILL BECOME MORE WIDESPREAD WITH LOWER
TO MIDDLE 60S SURFACE DEW POINTS IN MOST OF THE S-CNTRL
CONUS...BENEATH A STOUT CAPPING INVERSION THAT SHOULD LARGELY
INHIBIT WARM SECTOR/DRYLINE TSTM DEVELOPMENT. SHORTWAVE IMPULSES
EJECTING FROM THE WRN CONUS TROUGH ALSO DO NOT APPEAR FAVORABLY
TIMED FOR THE DIURNAL HEATING CYCLE...WITH GREATER MID-LEVEL HEIGHT
FALLS NOT ANTICIPATED TO OVERSPREAD THE WARM SECTOR UNTIL THE LATTER
HALF OF THE PERIOD. DAYTIME TSTM INITIATION WILL LIKELY BE TIED TO
THE COLD FRONT AND NEAR THE INTERSECTION OF THE MERGING COLD
FRONT/DRYLINE...WITH TSTM COVERAGE SUBSTANTIALLY INCREASING DURING
THE EVENING/OVERNIGHT. THE UNDERCUTTING NATURE OF THE COLD FRONT
SHOULD LIMIT THE SUSTAINABILITY OF ROBUST INDIVIDUAL UPDRAFTS.

NEVERTHELESS...STEEP MID-LEVEL LAPSE RATES AND STRONG DEEP-LAYER
SHEAR WILL BE FAVORABLE FOR SUPERCELL CLUSTERS INITIALLY PRODUCING
LARGE HAIL /SOME SIGNIFICANT/ ALONG WITH A FEW TORNADOES AND
ISOLATED DAMAGING WINDS. WITH TIME...AN EXTENSIVE LINE OF CONVECTION
SHOULD FORM BUT AS THE COLD FRONT BECOMES INCREASINGLY
ANAFRONTAL...SEVERE HAIL/WIND RISKS MAY BE SUBDUED. STILL...SOME
INCREASE IN TORNADO AND DAMAGING WIND THREAT IS POSSIBLE EARLY WED
MAINLY IN NERN TX/WRN AR AS LOW-LEVEL SLYS STRENGTHEN WITH APPROACH
OF THE SRN HIGH PLAINS IMPULSE.

..GRAMS.. 04/08/2013

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