Severe Thunderstorm Watch 415

Issued

Aug 8, 2021, 12:44 PM CDT (17:44 UTC)

Expired

Aug 8, 2021, 8:00 PM CDT

In force

7 hr

Issued by

the Storm Prediction Center

Largest hail expected

1.5 in

Strongest gust expected

60 kt

The St Louis radar (KLSX), 47 km from the middle of the area, began a volume at 17:46 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

5%

One or more EF2 to EF5 tornadoes

2%

Ten or more severe wind reports

50%

One or more gusts of 65 knots or more

20%

Ten or more severe hail reports

30%

One or more hailstones of 2 inches or more

10%

Six or more combined severe hail and wind reports

70%

• Mesoscale Discussion 1442 Severe potential...watch possibleAug 8, 11:40 AM CDT
• Mesoscale Discussion 1444 Severe thunderstorm watch 415Aug 8, 3:00 PM CDT
• Mesoscale Discussion 1447 Severe thunderstorm watch 415Aug 8, 5:47 PM CDT
• Mesoscale Discussion 1448 Severe thunderstorm watch 415Aug 8, 7:14 PM CDT

530 
WWUS20 KWNS 081741
SEL5  
SPC WW 081741
ILZ000-MOZ000-090100-

URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 415
NWS Storm Prediction Center Norman OK
1245 PM CDT Sun Aug 8 2021

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of 
  West central Illinois
  Much of eastern Missouri

* Effective this Sunday afternoon and evening from 1245 PM until
  800 PM CDT.

* Primary threats include...
  Scattered damaging wind gusts to 70 mph possible
  Isolated large hail events to 1.5 inches in diameter possible

SUMMARY...Thunderstorm development is expected this afternoon across
central Missouri, and storms will spread east-northeastward across
the remainder of eastern Missouri and into western Illinois by
mid-late afternoon.  The storm environment primarily favors
multicell clusters capable of producing damaging outflow winds of
60-70 mph, as well as isolated large hail of 1 to 1.5 inch diameter.

The severe thunderstorm watch area is approximately along and 65
statute miles east and west of a line from 40 miles north northwest
of Alton IL to 15 miles south southeast of West Plains MO. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU5).

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.

&&

AVIATION...A few severe thunderstorms with hail surface and aloft to
1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 550. Mean storm motion vector
24025.

...Thompson

Severe Thunderstorm Watches in Missouri, 2021Severe Thunderstorm Watches in Illinois, 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.