SWODY3
SPC AC 210730
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0230 AM CDT THU OCT 21 2010
VALID 231200Z - 241200Z
...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS LOWER MO VALLEY REGION
TO CENTRAL/SRN PLAINS...
...SYNOPSIS...
IN MID-UPPER LEVELS..BREAKDOWN OF WRN CONUS REX PATTERN DESCRIBED IN
DAY-2 OUTLOOK WILL BE COMPLETE BY THIS PERIOD...RESULTING IN
WEAKENING MID-UPPER LOW OVER NEB AND HEIGHT FALLS AHEAD OF SPEED MAX
OVER SWRN CONUS. BY 24/00Z...RESULT SHOULD BE BELT OF CYCLONICALLY
CURVED/ENHANCED FLOW ALOFT FROM SRN CA/AZ ACROSS NRN MEX AND SRN NM
THEN NEWD OVER W TX...OK AND OZARKS REGION.
AT SFC...LOW SHOULD MOVE FROM NWRN KS/SWRN NEB POSITION AROUND
23/12Z ACROSS SERN NEB TO IA...WITH WEAK COLD FRONT AND NEARLY
COLLOCATED DRYLINE SWWD ACROSS CENTRAL/ERN KS...CENTRAL/WRN OK AND
W-CENTRAL TX. MORE SPECIFIC POSITION OF THIS BOUNDARY REMAINS
UNCERTAIN ATTM...GIVEN VARIATIONS IN PROGGED SFC MASS-FIELD RESPONSE
TO SLOW-MOVING CYCLONE OVER CENTRAL PLAINS...AND TO UPSTREAM HEIGHT
CHANGES.
...LOWER MO VALLEY REGION TO CENTRAL/SRN PLAINS...
SCATTERED TSTMS MAY BE ONGOING EARLY IN PERIOD ACROSS ERN PORTIONS
ERN KS/OK AND PERHAPS NRN TX...BEHIND WHICH AIR MASS SHOULD
DESTABILIZE SUFFICIENTLY TO SUPPORT ADDITIONAL TSTM POTENTIAL DURING
AFTERNOON ALONG/AHEAD OF BOUNDARY.
ASIDE FROM BOUNDARY POSITIONING...MAIN CONCERN INVOLVES
EXTENT/DURATION OF POSTCONVECTIVE DESTABILIZATION DURING
AFTERNOON...INFLUENCING BUOYANCY AVAILABLE IN WHAT OTHERWISE SHOULD
BE ANOTHER WEAKLY CAPPED ENVIRONMENT. MORE SLY COMPONENT OF
MOIST-SECTOR WINDS THAN DAY-2 ALSO IS EXPECTED JUST E OF
BOUNDARY...PERHAPS RESULTING IN SOMEWHAT REDUCED CONVERGENCE EXCEPT
NEAR SFC LOW...AND UNCERTAINTIES REGARDING CONVECTIVE COVERAGE WITH
SWD EXTENT. BY CONTRAST...STRONGER HEATING...RICHER MOISTURE AND
LARGER CAPE ALSO ARE FCST SWD FROM OK INTO N TX. DEEP-LAYER SHEAR
AGAIN SHOULD BE FAVORABLE FOR SVR...BENEATH BROAD ZONE OF STG
MID-UPPER LEVEL WINDS. HODOGRAPHS AGAIN ARE FCST TO INCREASE IN
SIZE EWD AWAY FROM BOUNDARY AS WELL...WITH SOME VERY LARGE SRH
INDICATED BY OPERATIONAL WRF...ETA-KF AND SEVERAL SREF MEMBERS OVER
ERN OK/WRN AR/WRN MO/SERN KS.
DESPITE THESE MIXED SIGNALS IN PROGS...FAVORABLE BUOYANCY/SHEAR
SHOULD OVERLAP OVER MUCH OF CORRIDOR FROM CENTRAL/NE TX NNEWD TO
NWRN MO. PRIND AT LEAST WIDELY SCATTERED TSTMS WILL DEVELOP DURING
AFTERNOON...WITHIN ENVIRONMENT FAVORABLE FOR SUPERCELLS WITH LARGE
HAIL...DAMAGING GUSTS AND A FEW TORNADOES. THEREFORE...WILL
INTRODUCE CONDITIONAL 15%/SLGT RISK AREA ATTM...RECOGNIZING THAT IT
MAY BE SUBJECT TO SPATIAL MODIFICATION AND/OR SMALLER ZONE OF
GREATER PROBABILITIES WITH TIME AS MESOSCALE FOCI BECOME CLEARER.
..EDWARDS.. 10/21/2010
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