• Mesodiscussion 1296 for 2014

Mesodiscussion 1296




MESOSCALE DISCUSSION 1296
NWS STORM PREDICTION CENTER NORMAN OK
0153 PM CDT MON JUL 07 2014

AREAS AFFECTED...ERN MN...WI

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 071853Z - 072030Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...A SEVERE THREAT WILL CONTINUE TO DEVELOP ACROSS THE UPPER
MS VALLEY THIS AFTERNOON. ISOLATED LARGE HAIL AND WIND DAMAGE WILL
BE POSSIBLE WITH THE STRONGER UPDRAFTS...ALTHOUGH A TORNADO OR TWO
CANNOT BE RULED OUT. AS CELLS CONTINUE TO INCREASE IN COVERAGE...WW
ISSUANCE MAY BE NEEDED ACROSS THE REGION.

DISCUSSION...THE LATEST SFC ANALYSIS SHOWS 993-MB LOW OVER ONTARIO
WITH A COLD FRONT EXTENDING SWWD FROM THE LOW INTO THE LOWER OH
VALLEY. A DISTINCT POST-FRONTAL WIND SHIFT IS LOCATED FROM THE NORTH
SHORE OF LAKE SUPERIOR EXTENDING SWWD INTO CNTRL MN. SFC DEWPOINTS
AHEAD OF THE WIND SHIFT IN NRN WI AND CNTRL MN ARE IN THE LOWER TO
MID 60S F. THIS ALONG WITH SFC HEATING HAS RESULTED IN THE
DEVELOPMENT OF MODERATE INSTABILITY ACROSS THE MCD AREA WITH SBCAPE
ESTIMATED AROUND 1500 J/KG RANGE BY RAP-V2 DATA. SCATTERED
THUNDERSTORMS ARE INITIATING ALONG THE INSTABILITY CORRIDOR.
LARGE-SCALE ASCENT ASSOCIATED WITH A SHORTWAVE TROUGH EVIDENT ON
WATER VAPOR IMAGERY OVER THE UPPER MS VALLEY...SHOULD HELP
CONVECTIVE COVERAGE TO INCREASE OVER THE NEXT FEW HOURS. THE
MODERATE INSTABILITY ALONG WITH 30 TO 40 KT OF DEEP-LAYER SHEAR
EVIDENT ON REGIONAL WSR-88 VWPS SHOULD BE SUFFICIENT FOR ORGANIZED
MULTICELLS AND POSSIBLY A SUPERCELL THREAT. SUPERCELLS SHOULD BE
CAPABLE OF PRODUCING ISOLATED LARGE HAIL AND A TORNADO OR TWO CAN
NOT BE RULED OUT. CELLS THAT ORGANIZE INTO SHORT LINE SEGMENTS MAY
CONTAIN ISOLATED DAMAGING WIND GUSTS.

..BROYLES/EDWARDS.. 07/07/2014

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

ATTN...WFO...GRB...MKX...DLH...ARX...MPX...

LAT...LON   46289199 46479323 46029413 45089430 43969200 43648993
            44588894 45659030 46289199