ZCZC SPCSWOMCD ALL
ACUS11 KWNS 180806 
SPC MCD 180806 
WIZ000-IAZ000-MNZ000-180930-

MESOSCALE DISCUSSION 1460
NWS STORM PREDICTION CENTER NORMAN OK
0306 AM CDT SAT JUL 18 2015

AREAS AFFECTED...CNTRL/SRN WI...FAR SERN MN/NERN IA

CONCERNING...SEVERE THUNDERSTORM WATCH 434...

VALID 180806Z - 180930Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 434
CONTINUES.

SUMMARY...ALTHOUGH QLCS APPEARS TO BE PAST PEAK IN TERMS OF OVERALL
INTENSITY/ORGANIZATION...SWATHS OF STRONG WIND GUSTS PRODUCING TREE
DAMAGE SHOULD PERSIST TOWARDS SUNRISE. PROBABILITY OF DOWNSTREAM
SEVERE TSTM WATCH ISSUANCE IS 60 PERCENT.

DISCUSSION...MEASURED WIND GUSTS AROUND 40 KT CONTINUE ACROSS MOST
OF THE QLCS FROM W-CNTRL WI TO THE SERN MN/NERN IA BORDER WITH
OVERALL FORWARD SPEED AROUND 45 KT. RECENT VIL AND MID-LEVEL CAPPI
TRENDS SUGGEST THE FAR NRN PORTION OF THE LINE HAS BEGUN TO WEAKEN
GIVEN ITS PROGRESSION INTO A MORE STABLE AIR MASS PRESENT OVER NRN
WI. THIS SUGGESTS THE APEX OF THE LINE SHOULD TEND TO TRACK MORE
SEWD OVER PARTS OF CNTRL/SRN WI GIVEN A PERSISTENT NW/SE-ORIENTED
THETA-E/BUOYANCY GRADIENT WITH A RISK FOR SCATTERED WIND DAMAGE.
03-04Z ESRL-HRRR RUNS WHICH HAD SOME SEMBLANCE OF THE QLCS /ALTHOUGH
NOT AS WELL-DEFINED NOR AS FAST AS OBSERVED/...BOTH SUGGEST
SUBSTANTIAL WEAKENING OF CONVECTION TOWARDS DAYBREAK.

..GRAMS/EDWARDS.. 07/18/2015

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

ATTN...WFO...GRB...MKX...ARX...

LAT...LON   45379089 45368978 45048914 44748862 44458848 43968855
            43518883 43128934 43028983 42959051 42969105 43059162
            43199209 43499210 43829144 44119100 44779075 45379089 

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