MESO: Mesoscale Discussion 1836

ACUS11 KWNS 042158
SWOMCD
SPC MCD 042157
NEZ000-SDZ000-NDZ000-MTZ000-WYZ000-050000-

MESOSCALE DISCUSSION 1836
NWS STORM PREDICTION CENTER NORMAN OK
0457 PM CDT WED SEP 04 2013

AREAS AFFECTED...FAR EASTERN WY/WESTERN NEB/SOUTHEAST MT/WESTERN SD

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 042157Z - 050000Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...ISOLATED SEVERE TSTMS MAY DEVELOP ACROSS THE NORTH-CENTRAL
HIGH PLAINS THROUGH EARLY EVENING...POTENTIALLY INCLUDING PORTIONS
OF FAR EASTERN WY/NEB PANHANDLE AND WESTERN SD/SOUTHEAST MT.
LOCALIZED BOUTS OF DAMAGING WINDS AND SOME SEVERE HAIL WILL BE
POSSIBLE.

DISCUSSION...A DEEPLY MIXED CU FIELD AND SOME INITIAL TSTM
DEVELOPMENT CONTINUES TO OCCUR LATE THIS AFTERNOON /AS OF 2145Z/
ACROSS SOUTHEAST WY/NORTHEAST CO INTO THE NEB PANHANDLE...AND TO A
LESSER EXTENT ACROSS NORTHEAST WY/SD BLACK HILLS VICINITY. ON THE
NORTHERN PERIPHERY OF A CENTRAL ROCKIES-CENTERED UPPER RIDGE...MUCH
OF THIS DEEPLY MIXED BOUNDARY LAYER COINCIDES WITH A ROUGHLY
NORTH-SOUTH HIGH PLAINS LEE TROUGH...AND TO THE SOUTH OF ANGLING
FRONTAL ZONE FROM EASTERN MT INTO SD.

LATEST OBJECTIVE ANALYSIS SUGGESTS AROUND 1000-1500 J/KG
MLCAPE...ESPECIALLY ACROSS EASTERN WY/SOUTHWEST SD/NEB PANHANDLE.
EFFECTIVE SHEAR WITH MAGNITUDES ON THE ORDER OF 30-35 KT WILL
SUPPORT SOME SUSTAINED HIGH-BASED MULTICELLS/BRIEF SUPERCELLS. THE
DEEPLY MIXED NATURE OF THE BOUNDARY LAYER...WITH SURFACE
TEMPERATURE-DEWPOINT SPREADS AS HIGH AS 40-45 F...SUGGESTS STRONG
DOWNDRAFT POTENTIAL ASIDE FROM SOME SEVERE HAIL RISK THROUGH
EARLY/MID EVENING. THE ANTICIPATED MARGINAL/ISOLATED NATURE OF THE
OVERALL SEVERE RISK IS EXPECTED TO PRECLUDE A WATCH ISSUANCE.

..GUYER/EDWARDS.. 09/04/2013

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

ATTN...WFO...BIS...LBF...UNR...CYS...BYZ...

LAT...LON 46280538 46280391 43360235 41620217 41090405 43480485
46280538

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