114
ACUS11 KWNS 181006
SWOMCD
SPC MCD 181005
WIZ000-ILZ000-IAZ000-181230-
MESOSCALE DISCUSSION 0466
NWS STORM PREDICTION CENTER NORMAN OK
0505 AM CDT FRI APR 18 2025
AREAS AFFECTED...NORTHEAST IOWA...SOUTHERN WISCONSIN
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 181005Z - 181230Z
PROBABILITY OF WATCH ISSUANCE...20 PERCENT
SUMMARY...AN ISOLATED THREAT FOR LARGE HAIL AND SEVERE GUSTS WILL
LIKELY CONTINUE ACROSS PARTS OF NORTHEAST IOWA OVER THE NEXT FEW
HOURS. THE THREAT IS ALSO EXPECTED TO AFFECT PARTS OF SOUTHERN
WISCONSIN. WEATHER WATCH ISSUANCE IS UNLIKELY.
DISCUSSION...THE LATEST HIGH-RESOLUTION RADAR IMAGERY FROM DES
MOINES SHOWS A CLUSTER OF THUNDERSTORMS ACROSS NORTHEAST IOWA AND
FAR SOUTHWEST WISCONSIN. SOME OF THESE STORMS HAVE PRODUCED SEVERE
REPORTS OVER THE LAST COUPLE OF HOURS. THE CLUSTER WILL CONTINUE TO
MOVE EASTWARD INTO SOUTHERN WISCONSIN THIS MORNING. RAP FORECAST
SOUNDINGS FROM NORTHEAST IOWA INTO SOUTHERN WISCONSIN HAVE A
TEMPERATURE INVERSION UP TO ABOUT 850 MB. ACROSS NORTHEAST IOWA,
MUCAPE IS ESTIMATED BY THE RAP IN THE 1000 TO 2000 J/KG RANGE.
INSTABILITY FURTHER TO THE EAST IS CONSIDERABLY LESS, BUT AN
INCREASE IN INSTABILITY COULD STILL OCCUR AS WARM ADVECTION
CONTINUES THROUGH THE MORNING. IN ADDITION, RAP ANALYSIS ACROSS
NORTHEAST IOWA HAS EFFECTIVE SHEAR GENERALLY IN THE 40 TO 50 KNOT
RANGE. THIS ENVIRONMENT SHOULD SUPPORT ELEVATED SUPERCELLS CAPABLE
OF PRODUCING ISOLATED LARGE HAIL. IN SPITE OF THE LOW-LEVEL
TEMPERATURE INVERSION, A STRONG TO SEVERE GUST WILL ALSO BE
POSSIBLE. THE SEVERE THREAT SHOULD DEVELOP EASTWARD ACROSS SOUTHERN
WISCONSIN BUT MAY BECOME MORE ISOLATED AS THE STORMS OUTRUN THE
INSTABILITY FURTHER TO THE WEST.
..BROYLES/GLEASON.. 04/18/2025
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...LOT...MKX...DVN...ARX...DMX...
LAT...LON 42458882 42479059 42539253 42669327 43109340 43499266
43488999 43368824 42768793 42508828 42458882
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN
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