MESO: Mesoscale Discussion 0669

ACUS11 KWNS 172024
SWOMCD
SPC MCD 172023
SDZ000-NEZ000-NDZ000-MTZ000-WYZ000-172200-

MESOSCALE DISCUSSION 0669
NWS STORM PREDICTION CENTER NORMAN OK
0323 PM CDT FRI MAY 17 2013

AREAS AFFECTED...WRN SD...NEB PANHANDLE...NWRN NEB...NERN WY...SERN
MT

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 172023Z - 172200Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...TSTMS ARE EXPECTED TO INCREASE IN COVERAGE THROUGH THE
AFTERNOON. MODERATE INSTABILITY AND SHEAR WILL SUPPORT SOME
ORGANIZED STORM STRUCTURES WITH A THREAT OF SEVERE WIND AND HAIL.
AREA IS BEING MONITORED FOR A POSSIBLE WW.

DISCUSSION...WV IMAGERY SHOWS A BROAD REGION OF SWLY FLOW ACROSS THE
CNTRL/NRN HIGH PLAINS AHEAD OF A DEEPENING UPPER TROUGH OVER THE
GREAT BASIN. CONVECTION HAS BEEN INCREASING OVER THE HIGH TERRAIN OF
WYOMING...WITH ANOTHER AREA OF RECENT VIGOROUS TSTM DEVELOPMENT OVER
THE NEB PANHANDLE...ALONG A SFC WARM FRONT AND AHEAD OF A VORT MAX
OVER NERN CO.

20Z OBJECTIVE ANALYSIS INDICATES MODERATE SBCAPE OF 1000-2000 J/KG
ACROSS THE AREA...WITH EFFECTIVE SHEAR OF 35-45 KTS WHERE SWLY FLOW
ALOFT IS OVERSPREADING ELY FLOW AT THE SFC TO THE NORTH OF THE SFC
WARM FRONT. WITH THIS FAVORABLE COMBINATION OF
BUOYANCY/SHEAR...ORGANIZED STORM STRUCTURES WILL BE POSSIBLE.
CELLULAR STORM MODES WILL BE POSSIBLE INITIALLY WITH A THREAT OF
SEVERE HAIL AND WIND AND PERHAPS AN ISOLATED TORNADO. UPSCALE GROWTH
INTO ONE OR MORE CLUSTERS IS POSSIBLE LATER THIS AFTERNOON WHICH
WOULD MAINTAIN A THREAT OF DAMAGING WIND INTO THIS EVENING. WHILE
OVERALL COVERAGE OF THE SEVERE THREAT IS UNCERTAIN...THIS AREA WILL
BE MONITORED FOR A POSSIBLE WATCH.

..DEAN/WEISS.. 05/17/2013

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

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

LAT...LON 41440274 41940392 42760425 43390486 43620560 43780644
44310694 44910685 45580588 45920446 46120326 46120190
45940121 45570079 44960058 44400045 43960037 43340040
42700061 42010090 41650119 41490143 41450166 41420190
41440274

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