349
ACUS11 KWNS 180625
SWOMCD
SPC MCD 180624
WIZ000-ILZ000-IAZ000-180800-
MESOSCALE DISCUSSION 0767
NWS STORM PREDICTION CENTER NORMAN OK
0124 AM CDT MON MAY 18 2026
AREAS AFFECTED...EASTERN IOWA AND FAR SOUTHWESTERN WISCONSIN
CONCERNING...SEVERE THUNDERSTORM WATCH 219...
VALID 180624Z - 180800Z
THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 219
CONTINUES.
SUMMARY...AN OVERALL WEAKENING TREND IS EXPECTED TO CONTINUE WITH
THE THUNDERSTORM COMPLEX ACROSS IOWA. IF THIS TREND CONTINUES, THE
SEVERE THUNDERSTORM WATCH MAY NEED TO BE CANCELED EARLY.
DISCUSSION...A FORMERLY WELL ORGANIZED MCS CONTINUES TO MOVE EAST
ACROSS IOWA THIS MORNING. THE ENVIRONMENT AHEAD OF THE MCS REMAINS
QUITE UNSTABLE WITH OBJECTIVE ANALYSIS SUGGESTING GREATER THAN 2000
J/KG OF MUCAPE REMAINS. ADDITIONALLY, VAD PROFILE WINDS FROM
DAVENPORT, IA, INDICATES STRONG LOW-LEVEL CURVATURE WITHIN THE
LOWEST 1-KM LEADING TO 0-1KM SRH IN EXCESS OF 700 M2/S2 (AS COMPARED
TO ~300 M2/S2 ON OBJECTIVE ANALYSES).
HOWEVER, EFFECTIVE-LAYER SHEAR DECREASES MARKEDLY ACROSS IOWA FROM
WEST-TO-EAST, WITH LESS THAN 30 KNOTS ALONG AND AHEAD OF THE ONGOING
MCS. RADAR OBSERVATIONS SHOW THE EFFECTS OF THIS AS REGIONAL RADAR
DEPICTS A WEAKENING MCS WITH A GUST FRONT PUSHING AHEAD OF THE MAIN
CONVECTION. ADDITIONALLY, MRMS CAPPI PRODUCTS DEPICT A WEAKENING
TREND EVEN WITHIN THE STRONGEST UPDRAFT CORES.
GIVEN THE OBSERVATIONAL TRENDS AND THAT THE MCS CONTINUES TO MOVE
FARTHER AWAY FROM THE BETTER UPPER-LEVEL SUPPORT, THIS WEAKENING
TREND IS EXPECTED TO CONTINUE THROUGH THE MORNING. AN ISOLATED
SEVERE HAIL OR WIND REPORT CANNOT BE RULED OUT IN THE NEAR TERM,
HOWEVER, THE OVERALL TREND MAY SUPPORT CANCELING SEVERE THUNDERSTORM
WATCH #219 EARLY.
..MARSH.. 05/18/2026
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...MKX...DVN...ARX...DMX...
LAT...LON 40619304 41299269 41679260 41989179 42509132 43169096
43699091 43729031 43269012 42349053 41539097 40639168
40619304
MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page