SWODY2
SPC AC 171719
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1219 PM CDT TUE MAY 17 2011
VALID 181200Z - 191200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
OMEGA BLOCK WILL REMAIN IN PLACE ACROSS NORTH AMERICA WITH LARGE LOW
PRESSURE SYSTEM SITUATED ACROSS THE WRN CONUS AND A MORE COMPACT AND
VERTICALLY STACKED SYSTEM IN THE OH VALLEY/MID ATLANTIC STATES
REGION. WEAK SURFACE LOW IS EXPECTED TO BE ASSOCIATED WITH ERN U.S.
UPPER LOW...WHILE SURFACE LOW WITH WRN SYSTEM WILL BE SITUATED IN
THE SRN/CENTRAL HIGH PLAINS.
...KS AREA...
SURFACE LOW AND ASSOCIATED WARM FRONT SHOULD REMAIN SOUTH OF KS
...AT LEAST UNTIL LATE WEDNESDAY NIGHT. LOW LEVEL WARM ADVECTION IS
EXPECTED TO RESULT IN ELEVATED CONVECTION THROUGH MUCH OF THE
PERIOD. ELEVATED INSTABILITY IS FORECAST TO BE WEAK MOST OF WED
...SO THE SEVERE THREAT SHOULD BE LOW DURING THE DAYLIGHT HOURS.
HOWEVER...A 50-60 KT MID LEVEL JET IS FORECAST TO EJECT FROM THE WRN
UPPER TROUGH FROM NM NEWD INTO SWRN KS WED NIGHT. THIS FEATURE WILL
RESULT IN INCREASING DIFFLUENCE ALOFT... STRENGTHENING LOW LEVEL JET
AND STEEPENING MID LEVEL LAPSE RATES. INCREASING SHEAR AND
INSTABILITY ABOVE THE BOUNDARY LAYER MAY SUPPORT A FEW STORMS WITH
SEVERE HAIL OVERNIGHT.
...SRN PLAINS...
WHILE ENVIRONMENT WILL BECOME MORE FAVORABLE FOR SEVERE STORMS
...THE THREAT IS CONDITIONAL ON SURFACE BASED STORMS DEVELOPING.
SURFACE LOW IS FORECAST TO BE LOCATED IN THE WRN OK PANHANDLE REGION
LATE DAY...WITH WARM FRONT EXTENDING ESEWD INTO OK. INCREASING SLY
WINDS WILL ADVECT MID AND UPPER 60 DEWPOINTS... CURRENTLY LOCATED IN
SRN TX...ACROSS MUCH OF OK AND TX. HOWEVER ...STRONGER HEATING AND
MIXING WEST OF THE I-35 CORRIDOR SHOULD RESULT IN A DRYLINE TO
DEVELOP. WHILE STORMS THAT DEVELOP EAST OF THE DRYLINE/SOUTH OF WARM
FRONT CERTAINLY WOULD HAVE SUFFICIENT SHEAR/INSTABILITY FOR
SUPERCELLS...FORECAST SOUNDINGS INDICATE THE AIR MASS WILL BE
CAPPED. GIVEN THE WEAK FORCING...WARM ADVECTION MAY AID IN HIGHER
BASED STORMS. THE BEST PROBABILITY FOR SURFACE BASED STORMS TO
EVOLVE IS MOSTLY LIKELY NEAR THE DRYLINE WHERE THE CAPPING INVERSION
WOULD BE THE WEAKEST. GIVEN THE WEAK FORCING AND LOW PROBABILITY FOR
UPDRAFTS ROOTED IN THE BOUNDARY LAYER...ONLY LOW SEVERE
PROBABILITIES ARE FORECAST ATTM.
...MID ATLANTIC REGION...
MODELS MAINTAIN ESELY LOW LEVEL FLOW ACROSS THE MID ATLANTIC STATES
NWWD INTO PA. SURFACE DEW POINTS SHOULD AT LEAST REMAIN IN THE UPPER
50S...SUFFICIENT FOR WEAK INSTABILITY...WHICH WILL BE MAXIMIZED
DURING THE WARMER AFTERNOON HOURS. WITH 500 MB TEMPERATURES IN THE
-16 TO -18C RANGE AND DEEP LAYER SHEAR AROUND 30 KT...MULTICELL
STORMS...A FEW WITH SHORT LIVED WIND DAMAGE AND/OR HAIL...APPEAR
POSSIBLE. HOWEVER...THE WEAK INSTABILITY PRECLUDES A SLIGHT RISK
ISSUANCE.
..IMY.. 05/17/2011
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