173
ACUS11 KWNS 191902
SWOMCD
SPC MCD 191902
ILZ000-WIZ000-IAZ000-MOZ000-192000-

MESOSCALE DISCUSSION 1718
NWS STORM PREDICTION CENTER NORMAN OK
0202 PM CDT MON SEP 19 2016

AREAS AFFECTED...SRN INTO ERN IA / FAR NWRN IL / SWRN WI

CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY

VALID 191902Z - 192000Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...THUNDERSTORMS WILL LIKELY INITIATE DURING THE 19-22Z
PERIOD ACROSS SRN WI INTO CNTRL AND ERN IA.  SUPERCELLS WILL BE
CAPABLE OF LARGE TO VERY LARGE HAIL AND A RISK FOR A SUPERCELL
TORNADO.  A TORNADO WATCH IS LIKELY FOR PORTIONS OF SRN INTO ERN IA
AND ADJACENT PORTIONS OF IA/IL.

DISCUSSION...18Z SUBJECTIVE SURFACE MESOANALYSIS PLACES A 1012-MB
LOW 30 MI NW DSM WITH A FRONT EXTENDING NEWD FROM THE LOW INTO SRN
WI AND NEAR THE DOOR PENINSULA.  STORMS WILL LIKELY INITIATE NEAR
THE BOUNDARY AND THE LATEST RADAR/LIGHTNING DATA AT 1855Z SUGGESTS
INITIATION IS UNDERWAY IN SRN AND SERN WI.  THE STRONGER UPDRAFTS
MAY ACQUIRE ROTATION AND AN ISOLD HAIL/WIND RISK COULD DEVELOP WITH
THIS EARLY AFTERNOON ACTIVITY OVER SERN WI.

FARTHER W OVER CNTRL AND E-CNTRL IA...CONVECTIVE INHIBITION IS
GRADUALLY ERODING AS TEMPS WARM THROUGH THE 80S AND DEWPOINTS RISE
INTO THE LOWER 70S.  ONCE THE CAP IS BREACHED --MOST LIKELY DURING
THE 20-22Z PERIOD PER LATEST STORM-SCALE GUIDANCE-- STRONG BUOYANCY
/1500-2500 J PER KG MLCAPE/ WILL RESULT IN FAIRLY RAPID STORM
DEVELOPMENT.  THE LONG AND ENLARGING HODOGRAPH WITH TIME WILL
STRONGLY FAVOR A SUPERCELL MODE...DESPITE SOME EVENTUAL CLUSTERING
OF STORMS.  LARGE TO VERY LARGE HAIL WILL BE POSSIBLE WITH THE
STRONGER STORMS AND THE RISK FOR A SUPERCELL TORNADO MAY DEVELOP
DURING THE LATE AFTERNOON/EARLY EVENING TIMEFRAME.

..SMITH/THOMPSON.. 09/19/2016

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

ATTN...WFO...LOT...MKX...DVN...ARX...DMX...EAX...

LAT...LON   42269264 43118994 42818943 42308938 40559216 40479316
            41079402 42269264