WATCHES: Severe Thunderstorm Watch Number 589

WWUS20 KWNS 162038
SEL9
SPC WW 162038
ARZ000-OKZ000-TXZ000-170300-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 589
NWS STORM PREDICTION CENTER NORMAN OK
335 PM CDT THU JUL 16 2009

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

PARTS OF WESTERN AND SOUTHERN ARKANSAS
SOUTHEAST OKLAHOMA
FAR NORTHEAST TEXAS

EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 335 PM UNTIL
1000 PM 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 EITHER SIDE OF A LINE FROM 45 MILES SOUTH OF PINE
BLUFF ARKANSAS TO 10 MILES WEST NORTHWEST OF POTEAU OKLAHOMA.
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU9).

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 587...WW 588...

DISCUSSION...TSTMS ARE RAPIDLY DEVELOPING IN A HOT AND MOIST AIR
MASS WHERE MLCAPE HAS INCREASED TO 2500-3500 J/KG. REGION REMAINS
ON SRN FRINGE OF STRONGER MID/HIGH-LEVEL WIND FIELDS AND RESULTANT
DEEP-LAYER SHEAR. BUT...THE PRESENCE OF THE MODERATE TO STRONG
CONVECTIVE INSTABILITY SHOULD SUPPORT EVOLUTION OF A LARGE TSTM
CLUSTER WHICH WILL MOVE/PROPAGATE ALONG OUTFLOW BOUNDARY SITUATED
NW-SE ACROSS AREA. THE PRIMARY SEVERE WEATHER THREATS WILL BE
DAMAGING WINDS AND 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 29035.

...MEAD/WEISS

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