

477 

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

