208
WWUS20 KWNS 100139
SEL0
SPC WW 100139
IAZ000-ILZ000-INZ000-LMZ000-100900-
URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 550
NWS STORM PREDICTION CENTER NORMAN OK
840 PM CDT SUN AUG 9 2026
THE NWS STORM PREDICTION CENTER HAS ISSUED A
* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
FAR EAST-CENTRAL IOWA
NORTHERN ILLINOIS
FAR NORTHWEST INDIANA
LAKE MICHIGAN
* EFFECTIVE THIS SUNDAY NIGHT AND MONDAY MORNING FROM 840 PM
UNTIL 400 AM CDT.
* PRIMARY THREATS INCLUDE...
SCATTERED LARGE HAIL AND ISOLATED VERY LARGE HAIL EVENTS TO 2
INCHES IN DIAMETER POSSIBLE
SCATTERED DAMAGING WIND GUSTS TO 70 MPH POSSIBLE
A TORNADO OR TWO POSSIBLE
SUMMARY...THUNDERSTORM COVERAGE AND INTENSITY IS EXPECTED TO
INCREASE OVER THE NEXT FEW HOURS FROM FAR EAST-CENTRAL IOWA INTO
NORTHERN ILLINOIS AND EVENTUALLY FAR NORTHWEST INDIANA. LARGE HAIL
IS THE PRIMARY RISK INITIALLY, WITH AN INSTANCE OR TWO OF VERY LARGE
HAIL (I.E. 2" DIAMETER) POSSIBLE. UPSCALE GROWTH IS POSSIBLE OVER
TIME, WITH THE RESULTING CONVECTIVE LINE TRACKING SOUTHEASTWARD.
ADDITIONALLY, GIVEN THE RESIDUAL OUTFLOW BOUNDARY EXTENDING FROM FAR
NORTH-CENTRAL ILLINOIS INTO CENTRAL INDIANA, A LOW-PROBABILITY
TORNADO RISK EXISTS WITH ANY STORMS THAT CAN INTERACT WITH THIS
BOUNDARY.
THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 60
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 25 MILES WEST NORTHWEST
OF MOLINE IL TO 55 MILES EAST OF MARSEILLES IL. FOR A COMPLETE
DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE
(WOUS64 KWNS WOU0).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA.
PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING
WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE
WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE
TORNADOES.
OTHER WATCH INFORMATION...CONTINUE...WW 548...WW 549...
AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO
2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS. A
FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM MOTION VECTOR
27025.
...MOSIER
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