Tornado Watch 42

Issued

Mar 1, 2007, 3:58 AM CST (09:58 UTC)

Expired

Mar 1, 2007, 12:00 PM CST

In force

8 hr

Issued by

the Storm Prediction Center

Largest hail expected

2.5 in

Strongest gust expected

70 kt

The St Louis radar (KLSX), 170 km from the middle of the area, began a volume at 09:57 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

60%

One or more EF2 to EF5 tornadoes

40%

Ten or more severe wind reports

50%

One or more gusts of 65 knots or more

40%

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 226Mar 1, 12:12 AM CST
• Mesoscale Discussion 227Mar 1, 2:28 AM CST
• Mesoscale Discussion 231Mar 1, 3:35 AM CST

000
WWUS20 KWNS 011000
SEL2  
SPC WW 011000
ARZ000-ILZ000-MOZ000-011800-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 42
NWS STORM PREDICTION CENTER NORMAN OK
400 AM CST THU MAR 1 2007

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

       NORTHERN ARKANSAS
       SOUTHWEST ILLINOIS
       SOUTHERN AND EAST CENTRAL MISSOURI

EFFECTIVE THIS THURSDAY MORNING FROM 400 AM UNTIL NOON CST.

TORNADOES...HAIL TO 2.5 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 80 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 5 MILES NORTHWEST OF ALTON
ILLINOIS TO 50 MILES SOUTHEAST OF RUSSELLVILLE ARKANSAS.  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 39...WW 40...WW 41...

DISCUSSION...LINE OF SUPERCELL THUNDERSTORMS OVER SOUTHWEST MO INTO
WESTERN AR IS FORECAST TO TRANSLATE EAST-NORTHEASTWARD THIS MORNING
ACROSS WATCH AREA.  EXTREMELY STRONG LOW LEVEL WINDS...COUPLED WITH
APPROACHING 90-100 KT MID LEVEL JET WILL RESULT IN A VERTICAL SHEAR
ENVIRONMENT CONDUCIVE TO LONG TRACK SUPERCELLS CAPABLE OF
TORNADOES...LARGE HAIL...DAMAGING WINDS.  AIR MASS OVER EASTERN
PARTS OF WATCH ARE NOT PARTICULARLY UNSTABLE AT THIS TIME. 
HOWEVER...STRONG LOW LEVEL THERMAL/MOISTURE ADVECTION WILL HELP TO
RAPIDLY DESTABILIZE THIS AREA SHORTLY AFTER SUNRISE.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 70 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 24040.


...HART

Tornado Watches in Missouri, 2007Tornado Watches in Arkansas, 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.