MESO: Mesoscale Discussion 1770

ACUS11 KWNS 160121
SWOMCD
SPC MCD 160120
MIZ000-WIZ000-MNZ000-160245-

MESOSCALE DISCUSSION 1770
NWS STORM PREDICTION CENTER NORMAN OK
0820 PM CDT WED AUG 15 2012

AREAS AFFECTED...A LARGE PART OF MN...NWRN WI...FAR WRN PARTS OF THE
UPPER PENINSULA OF MI...WRN LAKE SUPERIOR

CONCERNING...SEVERE THUNDERSTORM WATCH 581...

VALID 160120Z - 160245Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 581
CONTINUES.

SUMMARY...WHILE AN ISOLATED MARGINALLY SVR STORM CANNOT BE RULED OUT
DURING THE NEXT HOUR OR TWO ACROSS SRN PARTS OF THE WW AREA...RADAR
AND ENVIRONMENTAL TRENDS SUGGEST THAT THE SVR THREAT IS DECREASING.

DISCUSSION...A FEW WEAKENING CONVECTIVE CLUSTERS EMBEDDED
WITHIN...AND RESIDING ON THE BACK EDGE OF...A REMNANT STRATIFORM
REGION CONTINUE PROGRESSING EWD/SEWD ACROSS THE WW AREA. THE
STRONGEST OF THIS ACTIVITY WILL CONTINUE TO ACROSS SRN PARTS OF THE
WW AREA...PERHAPS GLANCING SWRN PARTS OF THE MINNEAPOLIS AREA.
HOWEVER...FORMIDABLE CAPPING FOR A MIXED-LAYER PARCEL EVIDENT FROM
THE 00Z CHANHASSEN RAOB -- FORECAST TO INCREASE WITH NOCTURNAL
STABILIZATION -- WILL LIKELY YIELD A DECREASE IN INTENSITY OF THIS
CONVECTION.

FARTHER NORTH...THE LEADING/PARALLEL-STRATIFORM CHARACTER OF THE
REMNANT CONVECTIVE SYSTEM WILL ACT TO STABILIZE A BOUNDARY LAYER
THAT WAS ALREADY CHARACTERIZED BY WEAK LOW-LEVEL LAPSE RATES. AS
SUCH...ASSOCIATED CONVECTION WILL LIKELY STRUGGLE TO MAINTAIN
ONGOING WEAK/MODERATE INTENSITY...AND THE SVR THREAT HAS LARGELY
CEASED.

MODERATE STEERING-LAYER FLOW SHOULD TAKE A RISK FOR SUB-SEVERE
STORMS EAST OF REMAINING VALID PORTIONS OF THE WW AREA WITHIN THE
NEXT FEW HOURS. HOWEVER...WEAK INSTABILITY WILL PRECLUDE WW ISSUANCE
DOWNSTREAM.

..COHEN.. 08/16/2012

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

ATTN...WFO...MQT...GRB...DLH...ARX...MPX...FSD...

LAT...LON 45629497 47029426 48259304 47998990 46898941 44549124
43719267 43579382 43799492 44359538 45629497

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