MESO: Mesoscale Discussion 1567

ACUS11 KWNS 302137
SWOMCD
SPC MCD 302137
NDZ000-SDZ000-MTZ000-WYZ000-IDZ000-310000-

MESOSCALE DISCUSSION 1567
NWS STORM PREDICTION CENTER NORMAN OK
0437 PM CDT TUE JUL 30 2013

AREAS AFFECTED...PORTIONS OF SRN/ERN MT...WRN ND...NERN WY

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 302137Z - 310000Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...AN ISOLATED SVR THREAT WILL EXIST INTO THE EVENING HOURS.
WHILE TRENDS WILL BE MONITORED...THE ISSUANCE OF A WW IS CURRENTLY
UNLIKELY.

DISCUSSION...ISOLATED TO WIDELY SCATTERED CONVECTIVE DEVELOPMENT IS
ONGOING IN A VARIETY OF REGIMES:

/1/ OVER THE HIGHER TERRAIN AROUND SWRN/S-CNTRL MT FROM THE
BEAVERHEAD MOUNTAINS TO THE ABSAROKA RANGE WHERE ASCENT PRECEDING A
SUBTLE...LOW-AMPLITUDE...MID-LEVEL IMPULSE -- PER RECENT WATER VAPOR
IMAGERY -- IS LIKELY AUGMENTING THE ASCENDING BRANCHES OF OROGRAPHIC
CIRCULATIONS...
/2/ INVOF A WEAK COLD/QUASI-STATIONARY FRONT THAT ARCS FROM NWRN ND
INTO N-CNTRL MT...
/3/ ALONG A PRE-FRONTAL TROUGH S OF THE AFOREMENTIONED FRONT THAT
EXTENDS FROM N-CNTRL ND TO THE BIG SNOWY MOUNTAINS OF CNTRL MT AND
FARTHER SW INTO SWRN MT...AND
/4/ NEAR AND E OF THE BIG HORN MOUNTAINS OWING TO OROGRAPHIC ASCENT.

ENHANCED MID-LEVEL FLOW IN THE BASE OF A SHORTWAVE TROUGH
ACCOMPANYING THE PREVIOUSLY MENTIONED FRONT IS GLANCING THE AREA AND
WILL PROVIDE SUFFICIENT DEEP SHEAR FOR ORGANIZED CONVECTIVE
STRUCTURES AND PERHAPS SUPERCELLS. BLX VWP DATA INDICATE 40-55-KT
MID-LEVEL WLY/S BENEATH LOW-LEVEL ENELY/S...PROVIDING AROUND 50 KT
OF 0-6-KM BULK SHEAR. LOWER TROPOSPHERIC DIRECTIONAL SHEAR IS
MAXIMIZED S OF THE PREFRONTAL TROUGH AND N OF A WAVY...SECONDARY
QUASI-STATIONARY FRONT DRAPED W/E ACROSS S-CNTRL/SERN MT THAT ALSO
ARCS INTO S-CNTRL SD.

DESPITE FAVORABLE DEEP SHEAR PROFILES FOR ORGANIZED STORMS AND
MODESTLY RICH LOW-LEVEL MOISTURE FOR THESE ELEVATIONS -- E.G. SFC
DEWPOINTS IN THE UPPER 40S TO MIDDLE 50S -- BOUNDARY-LAYER BUOYANCY
IS RELATIVELY LIMITED ACROSS THE REGION. THIS IS THE CASE GIVEN SFC
TEMPERATURES ONLY IN THE MIDDLE/UPPER 70S. THE ABSENCE OF GREATER
BUOYANCY AND STRONGER DEEP FORCING FOR ASCENT WILL PROBABLY SUPPRESS
A MORE SUBSTANTIAL SVR THREAT FROM EVOLVING...THOUGH SPORADIC
INSTANCES OF LARGE HAIL AND POSSIBLY DAMAGING WIND GUSTS CANNOT BE
RULED OUT INTO THE EVENING HOURS.

..COHEN/EDWARDS.. 07/30/2013

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

ATTN...WFO...BIS...UNR...CYS...BYZ...GGW...RIW...TFX...PIH...

LAT...LON 44761213 45261120 46520986 47310802 48140428 47080288
46160310 45850409 44760403 43660419 43230490 43380579
44210620 45190812 44601074 44761213

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