SWODY2
SPC AC 231729
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1129 AM CST TUE NOV 23 2010
VALID 241200Z - 251200Z
...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS ERN OK...WRN/NRN
AR...SERN KS...MO...
...SYNOPSIS...
IN MID-UPPER LEVELS...PRIMARY FEATURE OF INTEREST WILL BE CYCLONE
NOW EVIDENT IN MOISTURE CHANNEL IMAGERY OVER INLAND NWRN CONUS.
THIS CYCLONE IS FCST OVER YELLOWSTONE REGION AT START OF
PERIOD...BASED ON STG CONSENSUS OF SREF MEMBERS AND LATEST 12Z
OPERATIONAL GUIDANCE. CYCLONE ALOFT SHOULD MOVE ENEWD TO ERN
ND/NWRN MN REGION BY 25/12Z...WITH OPERATIONAL NAM-WRF BEING
DISFAVORED SLOW OUTLIER AMONG ALL PROGS.
AT SFC...LEE CYCLONE NOW DEEPENING OVER CENTRAL HIGH PLAINS WILL
BECOME ATTACHED TO PRONOUNCED FRONTOGENETIC ZONE ACROSS WRN NEB
AROUND 24/12Z. STG COLD FRONT THEN SHOULD SURGE SEWD ACROSS CENTRAL
PLAINS AND SRN HIGH PLAINS...REACHING NEAR STL...FSM..ADM TO
W-CENTRAL/NW TX BY 15/12Z. COLD FRONTAL ZONE NOW ANALYZED FROM SRN
APPALACHIANS TO NE TX IS EXPECTED TO STALL OVER ARKLATEX REGION
DAY-1 THEN RETREAT NWD AS WARM FRONT ACROSS ERN OK...SERN KS...AND
OZARKS THROUGH 25/06Z...BEFORE BEING OVERTAKEN BY AFOREMENTIONED
PLAINS COLD FRONT. AFTERNOON DRYLINE OVER CENTRAL OK INTO N TX MAY
BE DIFFUSE...ALONG AND W OF MORE PRONOUNCED CONFLUENCE LINE
SEPARATING SWLY FROM SLY SFC FLOW FROM SERN KS SSWWD TO N TX.
...ERN OK TO MID MS VALLEY REGION...
SCATTERED/ELEVATED TSTMS...STRONGEST OF WHICH MAY PRODUCE SMALL
HAIL...MAY LINGER FROM END OF DAY-1 PERIOD OVER PORTIONS OZARKS
ALONG AND NE OF SFC WARM FRONT. FCST SOUNDINGS OVER THIS
REGION...BENEATH REGIME OF LOW-AMPLITUDE MEAN RIDGING
ALOFT...INDICATE WEAK LAPSE RATES LIMITING MUCAPE TO LESS THAN 400
J/KG IN MOST OF THIS REGIME. THIS ACTIVITY SHOULD SHIFT EWD IN STEP
WITH SUPPORTING LOW-LEVEL WAA REGIME ACROSS LOWER OH VALLEY
REGION...REINFORCING BAROCLINICITY ALONG PORTIONS WARM FRONT AND
PROBABLY RESHAPING/NARROWING WEDGE OF RETURNING WARM-SECTOR AIR
ACROSS ERN OK...SERN KS AND SWRN MO.
DURING AFTERNOON...SUBSTANTIAL SLY COMPONENT OF SFC FLOW S OF WARM
FRONT WILL ADVECT FAVORABLY MOIST AIR MASS NWD ACROSS ERN OK/WRN AR
AND OVER PORTIONS MO OZARKS...CHARACTERIZED BY SFC DEW POINTS
LOW-MID 60S F. WHEN COMBINED WITH DIABATIC SFC HEATING...THIS
SHOULD REMOVE MOST OR ALL MLCINH...BASED ON MODIFIED ETA-KF/WRF FCST
SOUNDINGS...AND OFFSET WEAK MIDLEVEL LAPSE RATES ENOUGH TO YIELD
500-1000 J/KG MLCAPE. CINH WILL INCREASE WITH SWD EXTENT ACROSS RED
RIVER REGION...MAKING CONVECTIVE POTENTIAL MORE CONDITIONAL INTO
N-CENTRAL/NE TX. PRESENCE OF PROGRESSIVELY WEAKER BUOYANCY WILL
HAVE SIMILAR EFFECT WITH NWD EXTENT OVER MO. DEEP-LAYER SHEAR WILL
BE QUITE FAVORABLE BENEATH STRENGTHENING MID-UPPER LEVEL JET. FCST
SOUNDINGS REASONABLY SUGGEST 50-60 KT EFFECTIVE SHEAR MAGNITUDE FROM
ARKLATEX NWD TO SRN/WRN MO BY 25/00Z. CURVED LOW-LEVEL HODOGRAPHS
ARE FCST...EVEN WITH SLGT WLY COMPONENT OF SFC WINDS ALONG
CONFLUENCE LINE...BENEATH BROAD/50-60 KT SSWLY/SWLY LLJ. TSTMS MAY
BACKBUILD SWWD ALONG COLD FRONT OVERNIGHT...BUT WITH MORE MRGL SVR
POTENTIAL DUE TO LIMITED INSTABILITY.
MAIN UNCERTAINTIES INVOLVE LACK OF MORE ROBUST LEVELS OF BUOYANCY
AND SFC CONVERGENCE...CASTING UNCERTAINTIES ON CONVECTIVE
TIMING/COVERAGE. HOWEVER POTENTIAL APPEARS TO BE SUFFICIENT TO
WARRANT AT LEAST 15% UNCONDITIONAL PROBABILITIES ATTM.
..EDWARDS.. 11/23/2010
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