WATCHES: Severe Thunderstorm Watch Number 170

WWUS20 KWNS 182125
SEL0
SPC WW 182125
ARZ000-KSZ000-MOZ000-OKZ000-190500-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 170
NWS STORM PREDICTION CENTER NORMAN OK
425 PM CDT SAT APR 18 2009

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

NORTHWEST ARKANSAS
SOUTHEAST KANSAS
SOUTHWEST MISSOURI
NORTHEAST OKLAHOMA

EFFECTIVE THIS SATURDAY AFTERNOON FROM 425 PM UNTIL MIDNIGHT 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 85
STATUTE MILES EAST AND WEST OF A LINE FROM 45 MILES NORTH
NORTHEAST OF CHANUTE KANSAS TO 30 MILES SOUTH SOUTHEAST OF POTEAU
OKLAHOMA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU0).

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 166...WW 167...WW
168...WW 169...

DISCUSSION...THUNDERSTORMS EXPECTED TO INCREASE IN NUMBER AND
INTENSITY ACROSS WATCH AREA THRU THE EVENING AS UPPER TROUGH
APPROACHES. STEEP...COOL LAPSE RATES IN PLACE COUPLED A
MOIST/UNSTABLE AIR MASS WILL BE CONDUCIVE TO LARGE HAIL IN MANY
STORMS. SUFFICIENT SHEAR FOR ROTATING STORMS BY EVENING AS UPPER
TROUGH APPROACHES. SOME OF AREA WILL BE MONITORED FOR POSSIBLE
UPGRADE TO TORNADO WATCH IF THESE CONDITIONS DEVELOP

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 450. MEAN STORM
MOTION VECTOR 24025.

...HALES

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