An outbreak of severe thunderstorms, including the potential for strong tornadoes, large hail, and widespread damaging winds, is expected this afternoon through evening, especially across Iowa, Missouri to northern Illinois, southeast Minnesota, and southern Wisconsin. In Arlington Heights and northwest Cook County, McHenry County, and Lake County the outbreak is likely to occur between 8:00 p.m. and 10:00 p.m. Tuesday, May 21, 2024.
Storms with tornado potential may weaken as they advance eastward across northern Illinois.
Multiple wind turbines have been destroyed by a tornado near Carl, Iowa – one of which is fully involved in fire. #iawx @NWSDesMoines pic.twitter.com/53D6AxEUEF
— Andrew Pritchard (@skydrama) May 21, 2024
The greatest chance for severe weather is in northwest Illinois, and storms with tornado potential are forecast to weaken as they move across northern Illinois toward Lake Michigan. However, gusty winds over 75 MPH are possible with storms that make it to northwest Cook County and Lake County.
The NOAA/NWS Storm Prediction center has northwest Cook County in an area with 5% risk experiencing a tornado within 25 miles.
Weather Radar shows a long line of thunderstorms from Minnesota to Oklahoma heading our way.
Clouds are blowing up in eastern Iowa and Missouri that are consistent with the radar imaging.
See also Arlingtoncardinal.com/clouds
A line of severe storms is expected to move across the area this evening bringing a threat for destructive winds and tornadoes. Here is a look at forecast arrival times across northern IL/northwest IN (storms may only persist in any one location for an hour or two). #ILwx #INwx pic.twitter.com/BbC9o2iwZT
— NWS Chicago (@NWSChicago) May 21, 2024
A line of severe thunderstorms is expected to move through the area this evening with the main threats of destructive winds in excess of 75 mph and tornadoes. Have multiple ways to receive warnings, including ways to wake you up! #ILwx #INwx pic.twitter.com/Yd3uiGfmrD
— NWS Chicago (@NWSChicago) May 21, 2024
O’HARE FORECAST …
Tuesday Night: Showers and thunderstorms, mainly before midnight. Some of the storms could be severe. Low around 60. Windy, with a south wind 20 to 30 mph, with gusts as high as 40 mph. Chance of precipitation is 80%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.
Wednesday: Mostly sunny, with a high near 76. West southwest wind around 15 mph, with gusts as high as 25 mph.
Wednesday Night: Mostly clear, with a low around 59. West southwest wind 5 to 10 mph, with gusts as high as 15 mph.
Thursday: Sunny, with a high near 82. South wind around 5 mph, with gusts as high as 10 mph.
Thursday Night: Mostly clear, with a low around 63. South southeast wind around 5 mph.
Friday: A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 1pm. Partly sunny, with a high near 83. Chance of precipitation is 60%.
Friday Night: A 50 percent chance of showers and thunderstorms, mainly before 1am. Mostly cloudy, with a low around 54.
Saturday: Sunny, with a high near 73.
Saturday Night: Partly cloudy, with a low around 55.
Sunday: A chance of showers after 1pm. Mostly sunny, with a high near 72.
Sunday Night: A chance of showers. Partly cloudy, with a low around 56.
Memorial Day: A chance of showers. Partly sunny, with a high near 69.
Monday Night: A chance of showers. Partly cloudy, with a low around 55.
Tuesday: A chance of showers. Mostly sunny, with a high near 71.
LAKE TEMPS …
SOUTHERN LAKE MICHIGAN WATER TEMPERATURES
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
907 AM CDT Tue May 21 2024
LAKE MICHIGAN WATER TEMPERATURES…
CHICAGO SHORE………..61.
CHICAGO CRIB…………59.
WAUKEGAN BUOY………..58.
WINTHROP HARBOR BUOY….57.
MICHIGAN CITY………..M.
SOUTH MID LAKE BUOY…..M.
CENTRAL MID LAKE BUOY…47.
NORTH MID LAKE BUOY…..48.
&&
M IS FOR MISSING DATA THAT IS NORMALLY AVAILABLE.
THE MICHIGAN CITY WATER TEMPERATURE SENSOR IS LOCATED AT
A WATER INTAKE ONE MILE OFFSHORE AND 60 FEET BELOW THE
WATER SURFACE. IT IS READ EVERY DAY OF THE YEAR.
Chicago Weather Forecast for your MAC/PC/TABLET includes surrounding suburbs.
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Chicago Weather Forecast for your MAC/PC/TABLET includes surrounding suburbs.
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Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
333 PM CDT Tue May 21 2024
.KEY MESSAGES…
– Severe thunderstorms likely this evening, with potential for widespread, and potentially significant, damaging winds and tornadoes
– Non-thunderstorm winds could gust over 40 mph from the south this evening, then from the southwest in the wake of the storms later tonight
– There will be dry breaks at times, but an active pattern for showers and storms returns Friday through early next week
&&
.DISCUSSION… Issued at 327 PM CDT Tue May 21 2024
Through Wednesday:
All eyes are on developing convection along a cold front extending from western Iowa through far eastern Kansas this afternoon. Low-level capping from previous WAA and some PBL mixing/drying continues to support dry conditions through at least 6-7pm in our area. Meanwhile, the spread in potential solutions from near-term CAM guidance is far higher than desired at this point, with guidance ranging from little/no convection over most of the CWA to an expansive squall line with significant damaging winds and an increased tornado threat well into the forecast area. Explosive growth of convection across eastern Kansas and far northwest Missouri supports maintaining a more aggressive approach with organized convection surviving well into the area, so we again made only some tweaks to the overall forecast and messaging with this update.
Overall expectations are for the ongoing upscale growth of the convection along the KS/MO line, ultimately developing a robust cold pool that will erode remaining capping and maintain organized convection across the MS River and into at least the western CWA around the 7-8pm window. Convection should then gradually weaken with eastward extent as the line becomes farther removed from the prime kinematic environment to the north. With that said, the highest coverage of potential significant winds favors areas roughly north of a line from LaSalle to Cook counties and especially in the northwest CWA toward the Rockford area.
All severe hazards are possible as the convection crosses the area this evening, but favors a transition to primarily damaging winds with eastward extent. Any convection, particularly linear/bowing segments and especially any QLCS, will support a damaging wind threat with the potential for swaths of significant wind gusts (75mph+) through the evening. Even decaying convection will support a significant damaging wind risk owing to substantial low-level shear profiles and a pre- convective pool of DCAPE up to around 1500J/kg.
The tornado risk will remain highly conditional on both storm evolution and coverage, with the most notable threat occurring with any QLCS/bowing structures owing to an impressive low-level wind profile with highly elongated hodographs and only a weakly decoupled nocturnal PBL. In fact, there may be a brief increase in tornado potential during the mid-evening as EHI values maximize with the increasing LLJ and slight increase in low- level moisture. As noted in earlier discussions, strong tornadoes (EF2) cannot be ruled out with any well-formed line segment.
Behind the convection just ahead of and behind the convection overnight, strong and gusty south to southwest synoptic winds will potentially gust to 40+mph for several hours, with some gusts possibly even reaching 50mph.
Cooler and dry conditions are expected Wednesday behind this system.
Kluber/NWS Chicago