Severe Thunderstorm Watch 739

Issued

Aug 7, 2011, 5:41 PM CDT (22:41 UTC)

Expired

Aug 8, 2011, 12:05 AM CDT

In force

6 hr

Issued by

the Storm Prediction Center

Largest hail expected

1.5 in

Strongest gust expected

65 kt

The St Louis radar (KLSX), 58 km from the middle of the area, began a volume at 22:41 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

10%

One or more EF2 to EF5 tornadoes

2%

Ten or more severe wind reports

70%

One or more gusts of 65 knots or more

20%

Ten or more severe hail reports

10%

One or more hailstones of 2 inches or more

5%

Six or more combined severe hail and wind reports

90%

• Mesoscale Discussion 1888Aug 7, 5:20 PM CDT
• Mesoscale Discussion 1893Aug 7, 8:27 PM CDT
• Mesoscale Discussion 1896Aug 7, 10:54 PM CDT

280 
WWUS20 KWNS 072241
SEL9
SPC WW 072241
ILZ000-MOZ000-080600-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 739
NWS STORM PREDICTION CENTER NORMAN OK
540 PM CDT SUN AUG 7 2011

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

       CENTRAL AND SOUTHERN ILLINOIS
       EAST CENTRAL AND SOUTHEAST MISSOURI

EFFECTIVE THIS SUNDAY AFTERNOON AND MONDAY MORNING FROM 540 PM
UNTIL 100 AM CDT.

HAIL TO 1.5 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 95
STATUTE MILES EAST AND WEST OF A LINE FROM 25 MILES NORTH
NORTHWEST OF SALEM ILLINOIS TO 50 MILES SOUTHWEST OF FARMINGTON
MISSOURI.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU9).

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 734...WW 735...WW
736...WW 737...WW 738...

DISCUSSION...COMPLEX CONVECTIVE SYSTEM IN CNTRL MO EXPECTED TO
CONTINUE GENERALLY E OR ESE AT ABOUT 35 KTS...WITH OCCASIONAL
STRONGER FORWARD-PROPAGATING SURGES AROUND 45 KTS.  THERMODYNAMIC
AND WIND ENVIRONMENT APPEAR FAVORABLE FOR ADDITIONAL
FORWARD-PROPAGATING SEGMENTS INTO STRONGLY HEATED/VERY MOIST AIR
OVER ERN MO AND WRN/SRN IL /REF MCD 1888/.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 65
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM
MOTION VECTOR 28035.


...CORFIDI

Severe Thunderstorm Watches in Illinois, 2011Severe Thunderstorm Watches in Missouri, 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.