DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 210721
SWODY3
SPC AC 210720

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0220 AM CDT MON MAY 21 2012

VALID 231200Z - 241200Z

...NRN KS TO SWRN MN...

MODELS CONTINUE TO SUGGEST HEIGHTS WILL FALL ACROSS THE GREAT BASIN
INTO THE CNTRL ROCKIES DURING THE DAY3 PERIOD AS A BELT OF STRONGER
FLOW SAGS SEWD TOWARD NRN NM. AS THE UPPER TROUGH ESTABLISHES
ITSELF OVER THE WRN U.S. LEE TROUGHING ACROSS THE HIGH PLAINS WILL
ENSURE SLY LOW LEVEL FLOW...AND POTENTIALLY MORE FAVORABLE
TRAJECTORIES FOR MOISTURE TO RETURN ACROSS THE WRN GULF BASIN.
LATEST DATA SUGGESTS THIS MORE SIGNIFICANT MOISTENING PROCESS WILL
BEGIN TO OCCUR LATE IN THE PERIOD AND MOST LIKELY REACH NO FARTHER
NORTH THAN TX WHERE MARITIME TROPICAL AIR SHOULD RETURN TO THE
COASTAL PLAINS.

ECMWF AND TO A LESSER DEGREE THE GFS SUGGEST A VERY STRONG CAP WILL
OVERSPREAD THE CNTRL PLAINS WHERE 700 MB TEMPERATURES COULD APPROACH
16C. THIS PLUME OF WARM AIR ALOFT SHOULD SPREAD NEWD ACROSS KS INTO
SERN NEB/SWRN IA BY EARLY EVENING. CAPPING WILL LIKELY BE AN ISSUE
IN THE DEVELOPMENT OF WARM SECTOR CONVECTION. WHILE THE NAM
SUGGESTS TSTMS MAY INITIATE ALONG THE COLD FRONT ACROSS WRN IA/SERN
NEB AROUND 00Z IT DOES SO PARTLY BY COOLING MID LEVEL TEMPERATURES
MUCH QUICKER THAN THE ECMWF/GFS. IT/S NOT CLEAR THAT THE CAP WILL
ERODE AS QUICKLY AS THE NAM IMPLIES AND CONVECTION MAY BE DELAYED
UNTIL AFTER SUNSET AND WITHIN A POST FRONTAL REGIME DRIVEN BY LOW
LEVEL WARM ADVECTION. FOR THIS REASON HAVE INTRODUCED 5% PROBS TO
ACCOUNT FOR THE UNCERTAINTY OF DAYTIME CONVECTION AND STRONG
CAPPING. HAIL/WIND WILL BE THE PRIMARY SEVERE THREATS WITH NEAR-SFC
BASED CONVECTION AND MOSTLY HAIL WITH ACTIVITY THAT EVOLVES NORTH OF
THE WIND SHIFT. LOW LEVEL WARM ADVECTION SHOULD PROVE INSTRUMENTAL
IN A CORRIDOR OF LATE NIGHT ELEVATED TSTMS THAT SHOULD
SPREAD/DEVELOP NEWD ACROSS CNTRL NEB INTO MN BY SUNRISE.

..DARROW.. 05/21/2012

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