

157 

WWUS20 KWNS 202255

SEL5

SPC WW 202255

ARZ000-LAZ000-OKZ000-TXZ000-210500-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 315

NWS STORM PREDICTION CENTER NORMAN OK

555 PM CDT FRI MAY 20 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       CENTRAL AND SOUTHWEST ARKANSAS

       EXTREME NORTHWEST LOUISIANA

       EXTREME SOUTHEAST OKLAHOMA

       NORTHEAST TEXAS



EFFECTIVE THIS FRIDAY AFTERNOON FROM 555 PM UNTIL MIDNIGHT CDT.



TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND

GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE

AREAS.



THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 75 STATUTE

MILES EAST AND WEST OF A LINE FROM 25 MILES WEST NORTHWEST OF HOT

SPRINGS ARKANSAS TO 30 MILES SOUTH OF LONGVIEW TEXAS.  FOR A

COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE

UPDATE (WOUS64 KWNS WOU5).



REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR

TORNADOES AND 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.



OTHER WATCH INFORMATION...THIS TORNADO WATCH REPLACES TORNADO

WATCH NUMBER 312. WATCH NUMBER 312 WILL NOT BE IN EFFECT AFTER

555 PM CDT. CONTINUE...WW 313...WW 314...



DISCUSSION...SEVERAL STORM CLUSTERS AND ASSOCIATED CONVECTIVE

OUTFLOWS WILL PERSIST ACROSS THE ARKLATEX REGION FOR THE NEXT FEW

HOURS.  A RESERVOIR OF MODERATE-STRONG INSTABILITY AND RICH BOUNDARY

LAYER MOISTURE WILL MAINTAIN A RISK FOR STORMS CAPABLE OF PRODUCING

OCCASIONAL LARGE HAIL AND DAMAGING WINDS.  ADDITIONALLY...DESPITE

WEAK FLOW ALOFT...VERTICAL SHEAR IN THE LOW-MIDLEVELS WILL REMAIN

SUFFICIENT FOR ROTATING STORMS AND THE RISK FOR A TORNADO OR

TWO...ESPECIALLY WHERE STORMS INTERACT WITH THE PRE-EXISTING OUTFLOW

BOUNDARY IN AR.



AVIATION...TORNADOES AND 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

600. MEAN STORM MOTION VECTOR 24025.





...THOMPSON

