MD 0912 CONCERNING SEVERE POTENTIAL…WATCH POSSIBLE FOR PORTIONS SERN WY…WRN NEB…EXTREME N-CENTRAL/NERN CO.
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
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...LBF...UNR...BOU...CYS...RIW...
LAT...LON 40840488 41650496 42260514 42680538 42820588 42890613
43380519 43360393 43060335 42300314 41660212 41510074
41090062 40560078 40740215 40770405 40840488
via SPC Forecast Products http://www.spc.noaa.gov/products/md/md0912.html
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