Severe Thunderstorm Watch 434

Issued

Aug 12, 2021, 5:19 PM CDT (22:19 UTC)

Expired

Aug 12, 2021, 10:00 PM CDT

In force

5 hr

Issued by

the Storm Prediction Center

Largest hail expected

1.5 in

Strongest gust expected

55 kt

The St Louis radar (KLSX), 141 km from the middle of the area, began a volume at 22:20 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

20%

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

10%

Six or more combined severe hail and wind reports

60%

• Mesoscale Discussion 1500 Severe potential...watch unlikelyAug 12, 2:22 PM CDT
• Mesoscale Discussion 1502 Severe potential...watch unlikelyAug 12, 3:30 PM CDT
• Mesoscale Discussion 1505 Severe thunderstorm watch 434Aug 12, 6:06 PM CDT
• Mesoscale Discussion 1506 Severe potential...watch possibleAug 12, 7:20 PM CDT

594 
WWUS20 KWNS 122218
SEL4  
SPC WW 122218
ILZ000-MOZ000-130300-

URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 434
NWS Storm Prediction Center Norman OK
520 PM CDT Thu Aug 12 2021

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of 
  parts of western Illinois
  portions of central and southern Missouri

* Effective this Thursday afternoon and evening from 520 PM until
  1000 PM CDT.

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

SUMMARY...A band of thunderstorms will continue shifting
southeastward across Missouri toward the Ozark Plateau, and into
adjacent portions of western Illinois.  Stronger storms within this
band will be capable of producing locally damaging wind gusts, and
hail in excess of 1" in diameter.

The severe thunderstorm watch area is approximately along and 50
statute miles north and south of a line from 35 miles southwest of
Knob Noster MO to 15 miles north northeast of Scott Afb IL. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU4).

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 431...WW 432...WW 433...

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
28040.

...Goss

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.