SWODY1
SPC AC 221954
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0254 PM CDT SAT OCT 22 2011
VALID 222000Z - 231200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF CENTRAL/SRN
OK...NORTH TX INTO THE ARKLATEX REGION...
...PARTS OF THE SRN PLAINS TO THE ARKLATEX...
PREVIOUS FORECAST REASONING REMAINS ON TRACK FOR TSTM INITIATION
OVER PARTS OF CENTRAL OK BY MID-LATE AFTERNOON /21-23Z/ PER
DEVELOPING CU FIELD FROM N-NE TX INTO SRN AND PARTS OF CENTRAL OK
ALONG AND S OF THE WARM FRONT. IN ADDITION...TIMING OF SEWD MOVING
SHORTWAVE TROUGH...NOW LOCATED OVER KS INTO NWRN OK...IS ALSO ON
TRACK TO AID IN UVVS FOR DEEP MOIST CONVECTION YET THIS AFTERNOON
OVER CENTRAL/SRN OK.
MESOSCALE DETAILS PROVIDED IN SPC MESOSCALE DISCUSSION #2268
INDICATED LARGE HAIL WILL BE THE PRIMARY THREAT WITH INITIAL
ACTIVITY AND THIS TREND CONTINUES TO BE INDICATED WITH THE SEVERE
HAIL PROBABILITIES...WHILE UPSCALE GROWTH INTO AN MCS REMAINS
POSSIBLE. THUS...GREATER SEVERE WIND PROBABILITIES ARE CENTERED
EITHER SIDE OF THE RED RIVER VALLEY. GIVEN THE E/SEWD EXTENSION OF
INSTABILITY INTO THE ARKLATEX REGION AND THE POTENTIAL FOR A FORWARD
PROPAGATING MCS /AND ATTENDANT SEVERE WEATHER THREATS/ THIS
EVENING/OVERNIGHT...THE SLIGHT RISK AREA HAS BEEN EXTENDED INTO MORE
OF THE ARKLATEX.
..PETERS.. 10/22/2011
.PREV DISCUSSION... /ISSUED 1113 AM CDT SAT OCT 22 2011/
...PARTS OF THE SRN PLNS THIS AFTN THROUGH EARLY TNGT...
MINOR CHANGES TO PREVIOUS FCST WERE MADE TO SHAVE OFF NWRN PARTS OF
SVR PROBABILITIES/CATEGORICAL SLIGHT RISK OVER WRN OK AND ADD TO THE
SRN FRINGE OF SVR RISKS IN N TX.
LLVL MOISTURE ADVECTION CONTINUES AS PLANNED WITH MID-UPR 50S DEW
POINTS ANTICIPATED BY MID-AFTN NEAR A WARM FRONT IN CNTRL/SRN OK AND
N TX /MLCAPES 500-1500 J PER KG/. AS FORMIDABLE UPR WAVE OVER WRN
KS BRUSHES ACROSS INSTABILITY AXIS...TSTMS WILL INITIATE 22-23Z IN
CNTRL OK ALA 12Z WRF-NMM/1.33KM NAM NESTED GRID. THOUGH MID-LVL WLY
FLOW EXHIBITS WEAKNESS...HIGH-LVL FLOW WILL BOOST EFFECTIVE SHEAR
AND A FEW SUPERCELLS WILL BE POSSIBLE THIS EVE. COOL THERMO
PROFILES AND 35-40 KT OF EFFECTIVE SHEAR WILL BE FAVORABLE FOR LARGE
HAIL.
FOCUSED AREA OF LLVL FORCING FOR ASCENT...AND CONTINUED ESE
AMPLIFICATION OF DIFLUENT UPR TROUGH SUGGEST THAT ACTIVITY COULD
EVOLVE INTO A SMALL FORWARD-PROPAGATING MCS OR TWO...WITH AN
ASSOCIATED HAIL/MARGINAL WIND THREAT POSSIBLY CONTINUING SE ACROSS
PARTS OF N TX AFTER DARK.
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