SWODY1
SPC AC 230555
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1255 AM CDT FRI MAY 23 2008
VALID 231200Z - 241200Z
...THERE IS A MDT RISK OF SVR TSTMS PORTIONS EXTREME SERN
WY...EXTREME NERN CO...SRN NEB PANHANDLE...SWRN AND EXTREME
S-CENTRAL NEB...W-CENTRAL/NERN KS...
...THERE IS A SLGT RISK OF SVR TSTMS ELSEWHERE FROM ERN WY TO
W-CENTRAL OK AND SERN NEB...
ANOTHER REGIONALIZED OUTBREAK OF SVR TSTMS...INCLUDING SUPERCELLS
WITH TORNADOES AND LARGE/DAMAGING HAIL...IS FCST ACROSS PORTIONS
CENTRAL HIGH PLAINS TODAY.
...SYNOPSIS...
PRIMARY UPPER AIR FEATURE FOR THIS FCST WILL CONTINUE TO BE LARGE
CYCLONIC GYRE COVERING MOST OF WRN CONUS. UPPER LEVEL MERIDIONAL
GRADIENT WINDS ARE FCST TO BE STRONGER TODAY THAN YESTERDAY ACROSS
MUCH OF THIS REGION...E.G. 70-80 KT AT 250 MB AS COMPARED TO 40-50
KT ANALYZED ON 23/00Z CHART AT THAT LEVEL...AS SPEED MAX PIVOTS
AROUND PERIPHERAL ERN SEMICIRCLE OF CYCLONE.
AT SFC...MODELS DIFFER SOMEWHAT ON POSITION OF SFC LOW ACROSS NERN
CO/SERN WY AREA...NAM BEING FARTHEST S AND OUTLIER WITH RESPECT TO
CONSENSUS OF SPECTRAL...MOST SREF MEMBERS AND PRIOR ECMWF RUN.
QUASISTATIONARY AND PRONOUNCED SFC BAROCLINIC ZONE WILL EXTEND ESEWD
FROM LOW ACROSS SERN NEB...N-CENTRAL AND E-CENTRAL KS. THIS FRONT
SHOULD MOVE LITTLE EXCEPT FOR LOCALIZED MODULATIONS RESULTING FROM
CONVECTIVE OUTFLOWS. DRYLINE SHOULD INTERSECT FRONT OVER NWRN KS
AND EXTEND SWD ACROSS ERN PORTIONS TX/OK PANHANDLES...MIXING
SLIGHTLY EWD DURING LATE MORNING THROUGH MID AFTERNOON AND
RETREATING SOMEWHAT WWD LATE AFTERNOON INTO OVERNIGHT HOURS.
...SERN WY TO NERN CO AND SWRN NEB...
SCATTERED-NUMEROUS TSTMS SHOULD DEVELOP....INITIALLY INVOF FRONTAL
ZONE OVER CYS RIDGE REGION...SRN PANHANDLE OF NEB...NERN CO AND SWRN
NEB...THROUGH MID AFTERNOON. THIS AREA WILL EXPERIENCE ADDITIONAL
MOIST ADVECTION AND UPSLOPE FLOW...AIDING IN TSTM DEVELOPMENT AND
MAINTENANCE...AND COMBINING WITH SFC HEATING TO YIELD ENHANCED SVR
THREAT IN NARROW/WNW-ESE ALIGNED CORRIDOR. ALTHOUGH BUOYANCY WILL
BE MRGL IN THIS SEGMENT OF FRONTAL ZONE...MLCAPES AROUND 500 J/KG
MAY DEVELOP CONCURRENT WITH VERY STG DEEP-LAYER SHEAR...E.G. 60-70
KT EFFECTIVE BULK SHEAR MAGNITUDES...AND 0-1 KM SRH 150-300 J/KG.
SEVERAL TORNADOES...A FEW POTENTIALLY SIGNIFICANT...ALONG WITH LARGE
HAIL AND SVR GUSTS...ARE POSSIBLE.
...CENTRAL/SRN PLAINS...
STRONG DIABATIC SFC HEATING...COMBINED WITH ASCENT ALONG DRYLINE AND
FRONT...SHOULD CONTRIBUTE TO ADDITIONAL DEVELOPMENT MID-LATE
AFTERNOON ALONG/AHEAD OF DRYLINE AND ALONG/S OF FRONT. SUPERCELLS
FORMING IN THIS REGIME WILL OFFER THREAT OF TORNADOES ANYTIME DURING
THEIR MATURITY...BUT PARTICULARLY UPON INTERACTING WITH FRONTAL
ZONE...WHERE LOW LEVEL VORTICITY...STORM-RELATIVE FLOW AND SRH ALL
ARE MAXIMIZED. STRONGER UPPER WINDS SHOULD ALLOW FOR MORE
PRECIPITATION VENTING DOWNSHEAR...PERHAPS COUNTERBALANCING
TENDENCIES FOR SEEDING AND INTERFERENCE FROM CLOSE-PROXIMITY STORMS.
THESE FACTORS..ALONG WITH AFOREMENTIONED ENVIRONMENTAL
INGREDIENTS...SUGGEST SEVERAL LONG-LIVED/CYCLIC SUPERCELLS AGAIN ARE
POSSIBLE...PRODUCING TORNADOES...SOME SIGNIFICANT...ALONG WITH LARGE
HAIL AND DAMAGING GUSTS.
OUTFLOW ASSOCIATED MCS NOW N OF OKC HAS CREATED AREA OF RELATIVELY
LOW THETAE AIR...HOWEVER THIS SHOULD ADVECT NWD AND MIX AWAY THROUGH
MORNING HOURS...AND ALLOW ROBUST MOISTURE RETURN NWD ACROSS WRN OK
AND WRN KS DURING DAYTIME. PRIND 60S F SFC DEW POINTS WILL BE
COMMON IN MOIST SECTOR BY AFTERNOON...WITH NARROW CORRIDOR OF 50S
EXTENDING NWWD INVOF FRONTAL ZONE TOWARD EXTREME NERN CO...NEB
PANHANDLE AND PORTIONS E-CENTRAL/SERN WY. THIS WILL COMBINE WITH
SFC HEATING AND STEEP MIDLEVEL LAPSE RATES TO YIELD 2000-3500 J/KG
MLCAPES. ALTHOUGH BUOYANCY WILL DIMINISH DURING EVENING...SEVERAL
HOURS OF SFC-BASED EFFECTIVE INFLOW PARCELS ARE EXPECTED AFTER
SUNSET...JUXTAPOSED WITH LARGE SRH RESULTING FROM LENGTHENING OF LOW
LEVEL HODOGRAPH BY LLJ. THEREFORE..TORNADO POTENTIAL SHOULD
CONTINUE INTO EVENING HOURS...FOLLOWED BY GEN WEAKENING OF OVERALL
SVR THREAT AFTER APPROXIMATELY 24/06Z.
..EDWARDS/SMITH.. 05/23/2008
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