Tornado Watch 717

Issued

Oct 17, 2007, 11:40 PM CDT (04:40 UTC)

Expired

Oct 18, 2007, 4:00 AM CDT

In force

4 hr

Issued by

the Storm Prediction Center

Largest hail expected

1.5 in

Strongest gust expected

60 kt

The St Louis radar (KLSX), 56 km from the middle of the area, began a volume at 04:43 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

40%

One or more EF2 to EF5 tornadoes

20%

Ten or more severe wind reports

50%

One or more gusts of 65 knots or more

40%

Ten or more severe hail reports

40%

One or more hailstones of 2 inches or more

30%

Six or more combined severe hail and wind reports

80%

• Mesoscale Discussion 2100Oct 17, 7:57 PM CDT
• Mesoscale Discussion 2103Oct 17, 10:56 PM CDT
• Mesoscale Discussion 2104Oct 18, 12:27 AM CDT
• Mesoscale Discussion 2105Oct 18, 2:02 AM CDT

000
WWUS20 KWNS 180438
SEL7  
SPC WW 180438
ILZ000-MOZ000-181100-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 717
NWS STORM PREDICTION CENTER NORMAN OK
1140 PM CDT WED OCT 17 2007

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

       WESTERN ILLINOIS
       CENTRAL AND EASTERN MISSOURI

EFFECTIVE THIS WEDNESDAY NIGHT AND THURSDAY MORNING FROM 1140 PM
UNTIL 600 AM CDT.

TORNADOES...HAIL TO 1.5 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 90 STATUTE
MILES EAST AND WEST OF A LINE FROM 40 MILES NORTH NORTHWEST OF
ALTON ILLINOIS TO 35 MILES EAST SOUTHEAST OF WEST PLAINS
MISSOURI.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).

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...THIS TORNADO WATCH REPLACES TORNADO
WATCH NUMBER 714. WATCH NUMBER 714 WILL NOT BE IN EFFECT AFTER
1140 PM CDT. CONTINUE...WW 713...WW 715...WW 716...

DISCUSSION...LINE OF STRONG TO SEVERE STORMS WILL CONTINUE TO TRACK
EASTWARD ACROSS MO AND INTO WESTERN IL DURING THE OVERNIGHT PERIOD. 
VERY STRONG VERTICAL SHEAR PROFILES COMBINED WITH SUFFICIENT
INSTABILITY MAY MAINTAIN A RISK OF ISOLATED TORNADOES...AS WELL AS
DAMAGING WINDS AND HAIL.

AVIATION...TORNADOES AND 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
500. MEAN STORM MOTION VECTOR 24035.


...HART

Tornado Watches in Missouri, 2007Tornado Watches in Illinois, 2007Every tornado watch in 2007

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.