Severe Thunderstorm Watch 340

Issued

May 23, 2011, 10:55 AM CDT (15:55 UTC)

Expired

May 23, 2011, 6:00 PM CDT

In force

7 hr

Issued by

the Storm Prediction Center

Largest hail expected

2 in

Strongest gust expected

65 kt

The St Louis radar (KLSX), 89 km from the middle of the area, began a volume at 15:57 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

60%

One or more gusts of 65 knots or more

40%

Ten or more severe hail reports

30%

One or more hailstones of 2 inches or more

40%

Six or more combined severe hail and wind reports

80%

• Mesoscale Discussion 885May 23, 7:38 AM CDT
• Mesoscale Discussion 889May 23, 10:34 AM CDT
• Mesoscale Discussion 892May 23, 12:12 PM CDT
• Mesoscale Discussion 893May 23, 12:37 PM CDT
• Mesoscale Discussion 894May 23, 1:16 PM CDT
• Mesoscale Discussion 897May 23, 2:52 PM CDT
• Mesoscale Discussion 900May 23, 3:58 PM CDT
• Mesoscale Discussion 901May 23, 4:24 PM CDT

820 
WWUS20 KWNS 231554
SEL0
SPC WW 231554
ILZ000-KYZ000-MOZ000-232300-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 340
NWS STORM PREDICTION CENTER NORMAN OK
1055 AM CDT MON MAY 23 2011

THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

       SOUTHWEST ILLINOIS
       WESTERN KENTUCKY
       EASTERN MISSOURI

EFFECTIVE THIS MONDAY MORNING AND EVENING FROM 1055 AM UNTIL 600
PM CDT.

HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 75
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 85
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 20 MILES WEST
SOUTHWEST OF FORT LEONARD WOOD MISSOURI TO 10 MILES NORTH OF
CARBONDALE ILLINOIS.  FOR A COMPLETE DEPICTION OF THE WATCH SEE
THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU0).

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 337...WW 338...WW 339...

DISCUSSION...MCS WITH WELL-DEFINED MCV IS EXPECTED TO RE-INTENSIFY
THIS AFTERNOON AS IT PROGRESSES EWD AND ENCOUNTERS AN INCREASINGLY
MOIST AND UNSTABLE AIR MASS ALONG THE MS RIVER WITH MLCAPE
INCREASING TO 2000-3000 J/KG.  THIS INSTABILITY COUPLED WITH A DEEP
WSWLY WIND FIELD WILL SUPPORT FORWARD-PROPAGATION OF MCS WITH THE
PRIMARY HAZARDS BEING CORRIDORS OF WIND DAMAGE AND LARGE HAIL.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 65
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM
MOTION VECTOR 27035.


...MEAD

Severe Thunderstorm Watches in Missouri, 2011Severe Thunderstorm Watches in Illinois, 2011Every severe thunderstorm watch in 2011

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.