Tornado Watch 142

Issued

Apr 15, 2011, 12:47 PM CDT (17:47 UTC)

Expired

Apr 15, 2011, 10:00 PM CDT

In force

9 hr

Issued by

the Storm Prediction Center

Largest hail expected

2 in

Strongest gust expected

60 kt

The St Louis radar (KLSX), 116 km from the middle of the area, began a volume at 17:49 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

60%

One or more EF2 to EF5 tornadoes

20%

Ten or more severe wind reports

30%

One or more gusts of 65 knots or more

30%

Ten or more severe hail reports

60%

One or more hailstones of 2 inches or more

40%

Six or more combined severe hail and wind reports

90%

• Mesoscale Discussion 437Apr 15, 12:29 PM CDT
• Mesoscale Discussion 439Apr 15, 3:32 PM CDT
• Mesoscale Discussion 442Apr 15, 5:57 PM CDT
• Mesoscale Discussion 447Apr 15, 8:15 PM CDT

206 
WWUS20 KWNS 151750
SEL2  
SPC WW 151750
ILZ000-KYZ000-MOZ000-160200-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 142
NWS STORM PREDICTION CENTER NORMAN OK
1250 PM CDT FRI APR 15 2011

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

       WESTERN AND SOUTHERN ILLINOIS
       WESTERN KENTUCKY
       EASTERN MISSOURI

EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 1250 PM UNTIL
900 PM CDT.

TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 85 STATUTE
MILES EAST AND WEST OF A LINE FROM 45 MILES SOUTH SOUTHWEST OF
PADUCAH KENTUCKY TO 70 MILES NORTH NORTHWEST OF ALTON ILLINOIS. 
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU2).

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 140...WW 141...

DISCUSSION...TSTMS ARE EXPECTED TO DEVELOP THIS AFTERNOON ALONG COLD
FRONT AND WITHIN DRY SLOT OF INTENSE MID TO UPPER-LEVEL CYCLONE. 
DAYTIME HEATING...BOUNDARY LAYER DEWPOINTS IN THE 50S AND 500 MB
TEMPERATURES OF AROUND -20 C WILL RESULT IN A STEEP LAPSE RATE
ENVIRONMENT WITH MLCAPE VALUES APPROACHING 1000-1500 J/KG.  WHEN
COUPLED WITH A VERTICALLY VEERING WIND PROFILE...SETUP WILL FAVOR
THE DEVELOPMENT OF SUPERCELLS CAPABLE OF TORNADOES AND LARGE HAIL.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
350. MEAN STORM MOTION VECTOR 21035.


...MEAD

Tornado Watches in Illinois, 2011Tornado Watches in Missouri, 2011Tornado Watches in Kentucky, 2011Every tornado 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.