DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 201714
SWODY2
SPC AC 201713

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1213 PM CDT TUE APR 20 2010

VALID 211200Z - 221200Z

...NO SVR TSTM AREAS FORECAST...

FAIRLY IMPRESSIVE UPPER TROUGH WILL MOVE ONSHORE ALONG THE CA COAST
BEFORE MOVING INTO THE GREAT BASIN LATE WEDNESDAY. DOWNSTREAM OF
THIS FEATURE...UPPER RIDGING WILL GRADUALLY SHIFT EAST INTO THE
CNTRL/SRN PLAINS AS HEIGHT FALLS SPREAD ACROSS THE SRN ROCKIES. AT
THE SURFACE...WEAK CYCLOGENESIS IN THE LEE OF THE SRN ROCKIES SHOULD
DAMPEN OUT OVER THE TX PANHANDLE EARLY IN THE PERIOD AS LARGE SCALE
FORCING BEGINS TO FOCUS ACROSS THE SRN ROCKIES IN ADVANCE OF UPPER
TROUGH. RESULTANT LEE TROUGH/DRY LINE SHOULD RETREAT INTO EXTREME
ERN NM BY PEAK HEATING WITH AN E-W SURFACE TROUGH OR WARM FRONT-LIKE
BOUNDARY EXPECTED TO EXTEND ALONG THE RED RIVER. THE RED RIVER
BOUNDARY WILL LIKELY SERVE AS THE DEMARCATION FOR EARLY-MID DAY
CONVECTION DRIVEN IN LARGE PART BY WARM ADVECTION. THIS
ACTIVITY...POSSIBLY AN MCS-LIKE CLUSTER...SHOULD SPREAD ACROSS OK
BEFORE WEAKENING OVER AR AS VEERED LLJ DECREASES AND BEGINS TO
RESPOND TO WRN U.S. TROUGH OVER THE SRN HIGH PLAINS. STRONG HEATING
WILL LIKELY BE FOCUSED OVER THE PLAINS OF ERN NM/WEST TX SOUTH OF
THE WARM FRONT AND FORECAST SOUNDINGS SUGGEST SFC-BASED PARCELS
COULD REACH THEIR CONVECTIVE TEMPERATURES ACROSS UPSLOPE REGIONS OF
THE HIGH PLAINS BY LATE AFTERNOON. EVEN SO...DEEP LAYER SHEAR IS
NOT EXPECTED TO BE PARTICULARLY STRONG...BUT VEERING PROFILES WITH
HEIGHT DO FAVOR ROTATING UPDRAFTS...ESPECIALLY WHERE LOW LEVEL FLOW
IS DECIDEDLY ELY ALONG/NORTH OF WARM FRONT. AT THIS TIME WILL
MAINTAIN 5% PROBABILITIES FOR PRIMARILY LARGE HAIL WITH ANY SLOW
MOVING SUPERCELLS. A SLIGHT RISK MAY NEED TO BE ADDED TO PORTIONS
OF THE SRN HIGH PLAINS IN LATER OUTLOOKS IF IT APPEARS DIURNAL
HEATING WILL CONTRIBUTE TO SUBSTANTIAL CONVECTIVE
DEVELOPMENT...PRIMARILY ACROSS THE TX SOUTH PLAINS.

..DARROW.. 04/20/2010

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