Severe Thunderstorm Watch 297

Issued

Jun 20, 2021, 9:40 PM CDT (02:40 UTC)

Expired

Jun 21, 2021, 2:00 AM CDT

In force

4 hr

Issued by

the Storm Prediction Center

Largest hail expected

1.5 in

Strongest gust expected

55 kt

Counties Cook County, IL, DuPage County, IL, Ford County, IL, Grundy County, IL, Iroquois County, IL, Kane County, IL, Kankakee County, IL, Kendall County, IL, Lake County, IL, Livingston County, IL, McHenry County, IL, Will County, IL, Benton County, IN, Jasper County, IN, Lake County, IN, Newton County, IN, Porter County, IN

The Chicago radar (KLOT), 51 km from the middle of the area, began a volume at 02:39 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

Two or more tornadoes

20%

One or more EF2 to EF5 tornadoes

5%

Ten or more severe wind reports

50%

One or more gusts of 65 knots or more

10%

Ten or more severe hail reports

20%

One or more hailstones of 2 inches or more

5%

Six or more combined severe hail and wind reports

70%

• Mesoscale Discussion 1040 Severe thunderstorm watch 295Jun 20, 7:14 PM CDT

953 
WWUS20 KWNS 210238
SEL7  
SPC WW 210238
ILZ000-INZ000-LMZ000-210700-

URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 297
NWS Storm Prediction Center Norman OK
940 PM CDT Sun Jun 20 2021

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of 
  Northeast Illinois
  Northwest Indiana
  Lake Michigan

* Effective this Sunday night and Monday morning from 940 PM
  until 200 AM CDT.

* Primary threats include...
  Scattered damaging wind gusts to 65 mph possible
  Isolated large hail events to 1.5 inches in diameter possible
  A tornado or two possible

SUMMARY...Clusters of storms will continue to move eastward across
northern Illinois toward the Chicagoland area and southern Lake
Michigan and eventually northwest Indiana. Damaging winds are the
most likely concern, but some severe hail is also possible and a
tornado cannot be ruled out.

The severe thunderstorm watch area is approximately along and 45
statute miles east and west of a line from 80 miles north northwest
of Valparaiso IN to 65 miles southwest of Valparaiso IN. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU7).

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 294...WW 295...WW 296...

AVIATION...A few severe thunderstorms with hail surface and aloft to
1.5 inches. Extreme turbulence and surface wind gusts to 55 knots. A
few cumulonimbi with maximum tops to 550. Mean storm motion vector
29030.

...Guyer

Severe Thunderstorm Watches in Illinois, 2021Severe Thunderstorm Watches in Indiana, 2021Every severe thunderstorm watch in 2021

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.