MESOSCALE DISCUSSION 0912

        MESOSCALE DISCUSSION 0912     NWS STORM PREDICTION CENTER NORMAN OK     0355 PM CDT SAT MAY 26 2012          AREAS AFFECTED...PORTIONS SERN WY...WRN NEB...EXTREME N-CENTRAL/NERN     CO.          CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE           VALID 262055Z - 262300Z          PROBABILITY OF WATCH ISSUANCE...60 PERCENT          SUMMARY...POTENTIAL IS INCREASING FOR DEVELOPMENT OF SVR     TSTMS...INCLUDING RISK OF SUPERCELLS AS WELL AS BOWING SEGMENTS.      FULL SPECTRUM OF SVR IS POSSIBLE.          DISCUSSION...20Z SFC MESOANALYSIS SHOWED CYCLONE BETWEEN     DEN-GXY-FCL...WHICH SHOULD MOVE/REDEVELOP NNEWD OVER WY/NEB BORDER     THROUGH 03Z.  VERY SHARPLY DEFINED WARM FRONT WAS DRAWN FROM LOW     ENEWD NEAR LBF-ODX-OFK LINE...AND WILL MOVE NWD OUT OF NERN CO AND     OVER WRN/CENTRAL NEB IN STEP WITH SFC LOW.  DIFFUSE/DOUBLE DRYLINE     STRUCTURE WAS ANALYZED FROM FRONT SWD ACROSS ERN CO AND WRN     KS...WITH MOIST AXIS EXTENDING FROM SRN SANDHILLS TO N PLATTE RIVER     VALLEY OF WY.  CONSIDERABLE CONFLUENCE ALSO WAS NOTED IN LATTER     AREA...WHICH MAY REMAIN UNTIL MERGING WITH NWD-MOVING WARM-FRONTAL     ZONE.  BACKED FLOW FROM THAT AREA EWD OVER PANHANDLE AND SWRN     NEB...PRIOR TO WARM FROPA...WILL MAINTAIN ENHANCED LOW-LEVEL     SHEAR/HODOGRAPH SIZE IN SUPPORT OF SUPERCELL POTENTIAL FOR ANY     RELATIVELY DISCRETE CONVECTION IN THAT REGIME.  ELY/UPSLOPE FLOW     ALSO WILL REPRESENT LOW-LEVEL ASCENT IN SERN WY CONFLUENCE ZONE.           N OF WARM FRONT...VIS IMAGERY SHOWS MARKED CLEARING OVER LARAMIE     COUNTY WY...SPREADING NWD ACROSS SRN PORTIONS PLATTE/GOSHEN     COUNTIES...AND SPREADING NWD ACROSS APPROXIMATELY SRN 1/2 OF NEB     PANHANDLE.  RELATED INSOLATION WILL ACT ON SFC DEW POINTS 50S F AND     STEEP MIDLEVEL LAPSE RATES TO SUPPORT ROUGHLY W-E ORIENTED CORRIDOR     OF 1500-2500 J/KG MLCAPE...JUXTAPOSED WITH 50-60 KT EFFECTIVE SHEAR     MAGNITUDE.  AIR MASS FARTHER N...ESPECIALLY FROM DGW-TOR-AIA LINE     NWD...HAS BEEN ENSHROUDED IN THICK LOW CLOUDS FOR MUCH OF     TODAY...WITH SOME DISPERSAL ONLY RECENTLY NOTED IN VIS IMAGERY.      THIS AREA WILL TAKE LONGER TO DESTABILIZE...THOUGH AREAS AS FAR N AS     EXTREME SWRN SD AND NEWCASTLE REGION MAY BECOME FAVORABLE BEFORE     DARK.  CORRIDOR BETWEEN GCC AND CENTRAL BLACK HILLS WILL REPRESENT     SW-NE GRADIENT WITHIN WHICH MLCAPE WILL DIMINISH MARKEDLY.  AS     SUCH...PERSISTENCE OF SFC-BASED EFFECTIVE INFLOW PARCELS BECOME MORE     UNCERTAIN AS FAR N AS I-80.  RELATED CINH ALSO WILL BE SLOW TO ERODE     OVER CENTRAL/NRN SANDHILLS OF NEB...LEADING TO RELATIVELY LOWERED     NEAR-TERM SVR PROBABILITIES THERE.          ..EDWARDS/CARBIN.. 05/26/2012