MESO: Mesoscale Discussion 1747

ACUS11 KWNS 212056
SWOMCD
SPC MCD 212056
NEZ000-COZ000-WYZ000-212230-

MESOSCALE DISCUSSION 1747
NWS STORM PREDICTION CENTER NORMAN OK
0356 PM CDT WED AUG 21 2013

AREAS AFFECTED...SOUTHEAST WY/FAR NORTHEAST CO TO WEST-CENTRAL NEB

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 212056Z - 212230Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...AT LEAST AN ISOLATED SEVERE TSTM POTENTIAL IS EXPECTED TO
INCREASE/DEVELOP GENERALLY EASTWARD THROUGH LATE AFTERNOON/EVENING
FROM EXTREME SOUTHEAST WY/FAR NORTHEAST CO INTO WEST-CENTRAL NEB.

DISCUSSION...A COLD FRONT EXTENDING ACROSS WESTERN/NORTHERN NEB WILL
CONTINUE TO SETTLE SOUTHWARD ACROSS THE REGION...WITH A
NEAR/POST-FRONTAL TREND OF INCREASING LOW-LEVEL EASTERLY UPSLOPE
TRAJECTORIES OVER THE PAST FEW HOURS ESPECIALLY ACROSS WESTERN
NEB/FAR SOUTHEAST WY. ALTHOUGH RELATIVELY THICK CLOUD COVER HAS BEEN
PREVALENT SINCE THIS MORNING...THE BOUNDARY LAYER CONTINUES TO
GRADUALLY DESTABILIZE WITH MLCAPE ROUGHLY RANGING FROM 500 J/KG NEAR
THE WY/NEB BORDER TO AS MUCH AS 2000-2500 J/KG INTO WEST-CENTRAL
NEB. AS THE AIRMASS CONTINUES TO DESTABILIZE...UPSLOPE TRAJECTORIES
AND INCREASING ISENTROPIC ASCENT /AIDED A NOCTURNALLY INCREASING LOW
LEVEL JET/ SHOULD LEAD TO INCREASING TSTM DEVELOPMENT ACROSS THE
REGION. MID TROPOSPHERIC WINDS ARE RELATIVELY MODEST...BUT
SUFFICIENT INSTABILITY/LOW-MID LEVEL VEERING WITH HEIGHT WILL
SUPPORT SUSTAINED MULTICELLS/FEW SUPERCELLS...WITH EVENTUAL MCS
DEVELOPMENT LATER TONIGHT. SEVERE HAIL/WIND ARE EXPECTED TO BE THE
PRIMARY HAZARDS.

..GUYER/CORFIDI.. 08/21/2013

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...LBF...BOU...CYS...

LAT...LON 41730469 42670483 42440373 42350296 42789966 42299903
41319962 40750144 40740331 41730469

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