WATCHES: Tornado Watch Number 855

WWUS20 KWNS 252021
SEL5
SPC WW 252021
ARZ000-MSZ000-TNZ000-260300-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 855
NWS STORM PREDICTION CENTER NORMAN OK
320 PM CDT SUN SEP 25 2011

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

EAST AND SOUTHEAST ARKANSAS
NORTHWEST MISSISSIPPI
SOUTHWEST TENNESSEE

EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 320 PM UNTIL
1000 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 70 STATUTE
MILES EAST AND WEST OF A LINE FROM 30 MILES SOUTH OF MONTICELLO
ARKANSAS TO 45 MILES NORTHWEST OF JACKSON TENNESSEE. FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU5).

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.

DISCUSSION...ASCENT IS INCREASING ALONG AND AHEAD OF A SURFACE LOW
AND COLD FRONT ACROSS NE AR...WHERE THUNDERSTORMS ARE BEGINNING TO
DEVELOP. DESPITE CLOUDS SPREADING E OF THE FRONT...A NARROW
CORRIDOR OF RICHER LOW-LEVEL MOISTURE ALONG THE FRONT AND STEEP
MIDLEVEL LAPSE RATES WILL SUPPORT MODERATE INSTABILITY AND
ADDITIONAL STORM DEVELOPMENT THIS AFTERNOON/EVENING.
MEANWHILE...DEEP-LAYER VERTICAL SHEAR IS FAVORABLE FOR SUPERCELLS
WITHIN A BROKEN BAND OF STORMS THAT IS EXPECTED ALONG THE COLD FRONT
THIS EVENING. LOW-LEVEL MOISTURE IS NOT IDEAL IN THE WARM
SECTOR...BUT STRONG LOW-LEVEL SHEAR WILL SUPPORT SOME RISK FOR A
TORNADO OR TWO WITH THE MORE DISCRETE STORMS. OTHERWISE...DAMAGING
WINDS/LARGE HAIL WILL BE POSSIBLE AS CONVECTION INCREASES IN
COVERAGE THIS EVENING...AND STORMS BACK-BUILD ALONG THE FRONT INTO
SE AR/NW MS.

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
500. MEAN STORM MOTION VECTOR 28025.

...THOMPSON

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