Tornado Watch 424

Issued

Aug 11, 2021, 12:17 PM CDT (17:17 UTC)

Expired

Aug 11, 2021, 8:00 PM CDT

In force

8 hr

Issued by

the Storm Prediction Center

Largest hail expected

3 in

Strongest gust expected

65 kt

The Green Bay radar (KGRB), 55 km from the middle of the area, began a volume at 17:17 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

70%

One or more EF2 to EF5 tornadoes

20%

Ten or more severe wind reports

60%

One or more gusts of 65 knots or more

60%

Ten or more severe hail reports

60%

One or more hailstones of 2 inches or more

60%

Six or more combined severe hail and wind reports

95%

• Mesoscale Discussion 1478 Severe potential...tornado watch likelyAug 11, 11:48 AM CDT
• Mesoscale Discussion 1483 Tornado watch 424Aug 11, 2:02 PM CDT
• Mesoscale Discussion 1489 Tornado watch 424Aug 11, 5:40 PM CDT

968 
WWUS20 KWNS 111715
SEL4  
SPC WW 111715
IAZ000-MIZ000-MNZ000-WIZ000-LMZ000-120100-

URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 424
NWS Storm Prediction Center Norman OK
1215 PM CDT Wed Aug 11 2021

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of 
  Extreme northeast Iowa
  The south central Upper Peninsula of Michigan
  Extreme southeast Minnesota
  Much of central Wisconsin
  Lake Michigan

* Effective this Wednesday afternoon and evening from 1215 PM
  until 800 PM CDT.

* Primary threats include...
  A few tornadoes likely
  Scattered damaging winds and isolated significant gusts to 75
    mph likely
  Scattered large hail and isolated very large hail events to 3
    inches in diameter likely

SUMMARY...Scattered supercell development is expected this afternoon
along and ahead of a cold front moving toward central Wisconsin. 
The storm environment is favorable for several tornadoes and very
large hail near the size of baseballs with the initial supercells. 
Some clustering of storms could occur later this afternoon, which
would support an increasing threat for damaging wind swaths, some of
which could be significant (near 75 mph).

The tornado watch area is approximately along and 75 statute miles
east and west of a line from 15 miles northwest of Iron Mountain MI
to 35 miles south of Lonerock WI. For a complete depiction of the
watch see the associated watch outline update (WOUS64 KWNS WOU4).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Tornado Watch means conditions are favorable for
tornadoes and 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.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 422...WW 423...

AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 3 inches. Extreme turbulence and surface wind
gusts to 65 knots. A few cumulonimbi with maximum tops to 600. Mean
storm motion vector 28030.

...Thompson

Tornado Watches in Wisconsin, 2021Tornado Watches in Iowa, 2021Tornado Watches in Michigan, 2021Every tornado 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.