MESO: Mesoscale Discussion 1804

ACUS11 KWNS 301928
SWOMCD
SPC MCD 301927
SDZ000-NEZ000-WYZ000-302130-

MESOSCALE DISCUSSION 1804
NWS STORM PREDICTION CENTER NORMAN OK
0227 PM CDT FRI AUG 30 2013

AREAS AFFECTED...FAR ERN WY...SWRN SD...WRN NEB PANHANDLE

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 301927Z - 302130Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...TSTM ACTIVITY IS EXPECTED TO INCREASE WITHIN THE NEXT HOUR
OR TWO WITH SCATTERED COVERAGE ANTICIPATED. SOME OF THESE STORMS MAY
BE CAPABLE OF SVR HAIL/WIND AND THE AREA WILL BE MONITORED FOR A
POSSIBLE WW.

DISCUSSION...RECENT LIGHTNING WITHIN THE CONVECTION ALONG THE BLACK
HILLS AND LARAMIE MOUNTAINS HAS INCREASED CONFIDENCE THAT THE
ENVIRONMENT ACROSS THE CNTRL PLAINS IS GRADUALLY BECOMING MORE
SUPPORTIVE OF SURFACE-BASED CONVECTIVE INITIATION. 12Z RAP SOUNDING
MODIFIED FOR 19Z SURFACE OBSERVATION -- 93/62 -- YIELDS STRONG
SURFACE-BASED INSTABILITY /SBCAPE OVER 3000 J PER KG/ AND LITTLE
REMAINING CINH. INCREASED CONVERGENCE ALONG A WEAK SURFACE TROUGH
AND CONTINUED DESTABILIZATION FOSTERED BY ISOLATION IS EXPECTED TO
RESULT IN ADDITIONAL SURFACE-BASED CONVECTIVE DEVELOPMENT DURING THE
NEXT HOUR OR TWO.

MUCH OF THE MD AREA IS WITHIN THE SRN PERIPHERY OF SOME MODESTLY
ENHANCED MID-LEVEL FLOW ASSOCIATED WITH A SHORTWAVE TROUGH
PROGRESSING THROUGH SRN SK. AS A RESULT...EFFECTIVE SHEAR VALUES ARE
CURRENTLY ESTIMATED AROUND 35 TO 40 KT...WHICH IS SUBSTANTIAL ENOUGH
TO SUPPORT ORGANIZED CONVECTION. SCATTERED TSTM COVERAGE APPEARS
LIKELY WITH SOME POTENTIAL SVR. PRIMARY SVR THREATS WILL BE LARGE
HAIL AND DAMAGING WINDS. CONVECTIVE TRENDS WILL BE MONITORED FOR A
POSSIBLE WW.

..MOSIER/GOSS.. 08/30/2013

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

ATTN...WFO...LBF...UNR...CYS...

LAT...LON 44550441 44850397 44900313 43920228 41500284 41140445
42820522 44550441

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