WATCHES: Severe Thunderstorm Watch Number 74

WWUS20 KWNS 292327
SEL4
SPC WW 292327
ARZ000-LAZ000-MSZ000-300700-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 74
NWS STORM PREDICTION CENTER NORMAN OK
625 PM CDT TUE MAR 29 2011

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

SOUTHEAST ARKANSAS
NORTHERN LOUISIANA
NORTHERN AND CENTRAL MISSISSIPPI

EFFECTIVE THIS TUESDAY NIGHT AND WEDNESDAY MORNING FROM 625 PM
UNTIL 200 AM CDT.

HAIL TO 1.5 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 55
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 45 MILES NORTHWEST
OF NATCHITOCHES LOUISIANA TO 35 MILES NORTH NORTHEAST OF MERIDIAN
MISSISSIPPI. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU4).

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 72...WW 73...

DISCUSSION...ELEVATED TSTMS ARE EXPECTED TO INCREASE IN COVERAGE AND
INTENSITY THIS EVENING IN ADVANCE OF POTENT SHORT-WAVE TROUGH
TRANSLATING ESEWD THROUGH KS/OK. INCREASING LOW-LEVEL WARM THERMAL
AND MOISTURE ADVECTION BENEATH A STEEP MIDLEVEL LAPSE RATE PLUME
WILL RESULT IN SUFFICIENT INSTABILITY FOR VIGOROUS UPDRAFT GROWTH.
WHEN COUPLED WITH 40-45 KT OF EFFECTIVE BULK SHEAR...ENVIRONMENT
WILL BE SUPPORTIVE OF PERIODIC SUPERCELL STRUCTURES WITH THE MAIN
THREAT BEING LARGE HAIL.

AVIATION...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 24025.

...MEAD

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