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WWUS20 KWNS 132035

SEL7

SPC WW 132035

ARZ000-ILZ000-INZ000-KYZ000-MOZ000-MSZ000-TNZ000-140400-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 577

NWS STORM PREDICTION CENTER NORMAN OK

335 PM CDT MON AUG 13 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       EASTERN ARKANSAS

       SOUTHERN ILLINOIS

       SOUTHWEST INDIANA

       WESTERN KENTUCKY

       SOUTHEAST MISSOURI

       NORTHERN MISSISSIPPI

       WESTERN TENNESSEE



EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 335 PM UNTIL

1100 PM CDT.



HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70

MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 75

STATUTE MILES EAST AND WEST OF A LINE FROM 35 MILES EAST

NORTHEAST OF MOUNT VERNON ILLINOIS TO 55 MILES SOUTH SOUTHEAST OF

GREENVILLE MISSISSIPPI.  FOR A COMPLETE DEPICTION OF THE WATCH

SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).



REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE

FAVORABLE FOR 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. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY

DO PRODUCE TORNADOES.



OTHER WATCH INFORMATION...CONTINUE...WW 576...



DISCUSSION...STORMS ARE EXPECTED TO INCREASE IN COVERAGE AND

INTENSITY THROUGH THE EVENING HOURS AS AN UPPER TROUGH AND

ASSOCIATED COLD FRONT SPREAD EAST ACROSS INSTABILITY AXIS ALIGNED N

TO S FROM SWRN IND AND SRN IL TO THE MS RIVER BETWEEN ERN AR AND WRN

MS. INSTABILITY /MLCAPE/ WITHIN THIS CORRIDOR RANGES FROM AROUND

2000 J/KG IN THE SOUTH TO AROUND 800 J/KG IN THE NORTH. EFFECTIVE

SHEAR MAGNITUDES WILL RANGE FROM ABOUT 25KT SOUTH TO OVER 30KT

NORTH. LINEAR FORCING ALONG THE FRONT AND MODEST INCREASE IN LARGE

SCALE ASCENT ASSOCIATED WITH THE UPPER TROUGH SHOULD SUPPORT THE

DEVELOPMENT OF SHORT LINE SEGMENTS AND/OR STORM CLUSTERS WITH

ADEQUATE SHEAR AND INSTABILITY FOR A MORE ORGANIZED STORM THREAT TO

EVOLVE WITH TIME. DAMAGING WINDS AND SOME LARGE HAIL APPEAR TO BE

THE GREATEST HAZARDS WITH THIS DEVELOPING ACTIVITY INTO THE EVENING

HOURS.



AVIATION...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 26025.





...CARBIN

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