WATCHES: Severe Thunderstorm Watch Number 61

WWUS20 KWNS 260354
SEL1
SPC WW 260354
ARZ000-LAZ000-OKZ000-TXZ000-261100-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 61
NWS STORM PREDICTION CENTER NORMAN OK
1050 PM CDT FRI MAR 25 2011

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

WESTERN ARKANSAS
NORTHWEST LOUISIANA
SOUTH-CENTRAL AND SOUTHEAST OKLAHOMA
NORTHEAST TEXAS

EFFECTIVE THIS FRIDAY NIGHT AND SATURDAY MORNING FROM 1050 PM
UNTIL 600 AM 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 70
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 45 MILES NORTHWEST
OF DURANT OKLAHOMA TO 50 MILES EAST OF TEXARKANA ARKANSAS. FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU1).

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.

DISCUSSION...TSTMS ARE EXPECTED TO INCREASE IN COVERAGE AND
INTENSITY OVERNIGHT TO THE N OF QUASI-STATIONARY BOUNDARY EXTENDING
FROM SFC LOW OVER N-CNTRL TX ESEWD INTO NRN LA. THE COMBINATION OF
STEEP MIDLEVEL LAPSE RATES AND INCREASING LOW-LEVEL MOISTURE ARE
YIELDING A MODERATELY UNSTABLE AIR MASS WITH MUCAPE OF 1000-2000
J/KG.
CURRENT THINKING IS THAT NOCTURNAL COOLING IN THE BOUNDARY LAYER AND
MODEST MOISTURE CONTENT WILL RESULT IN SUFFICIENT SURFACE-BASED
CONVECTIVE INHIBITION SUCH THAT STORMS SHOULD REMAIN SLIGHTLY
ELEVATED. GIVEN THE PRESENCE OF 40-50 KT OF EFFECTIVE BULK
SHEAR...ENVIRONMENT WILL BE SUPPORTIVE OF SUPERCELLS. WHILE A BRIEF
TORNADO IS POSSIBLE...HAIL APPEARS TO BE THE PRIMARY HAZARD.

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 27035.

...MEAD

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