

710 

WWUS20 KWNS 071913

SEL0

SPC WW 071913

OKZ000-TXZ000-080300-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 870

NWS STORM PREDICTION CENTER NORMAN OK

110 PM CST MON NOV 7 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       WEST CENTRAL AND SOUTHWEST OKLAHOMA

       NORTHWEST TEXAS



EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 110 PM UNTIL 900

PM CST.



TORNADOES...HAIL TO 2.5 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 60 STATUTE

MILES EAST AND WEST OF A LINE FROM 45 MILES NORTH NORTHEAST OF

CLINTON OKLAHOMA TO 75 MILES SOUTH SOUTHEAST OF CHILDRESS TEXAS.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU0).



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.



DISCUSSION...CUMULUS STREETS HAVE GRADUALLY BEEN DEEPENING THIS AFTN

AS WEAK ASCENT...TIED TO A LEAD MID-LVL SHORTWAVE TROUGH...EJECTS

ENE ACROSS THE WARM SECTOR.  AIR MASS HAS BECOME MODERATELY UNSTABLE

AS PLENTIFUL LLVL MOISTURE STREAMS NWD BENEATH STEEP MID-LVL LAPSE

RATES.  NATURE OF ASCENT /WEAK-MODEST/ AND DEEP-LAYER SHEAR VECTORS

LARGELY NORMAL TO INITIATING BOUNDARIES WILL CONTRIBUTE TO BOTH

LINEAR AND DISCRETE CELLS WITH POTENTIAL FOR VERY LARGE HAIL.  LLVL

SHEAR...WHILE SOMEWHAT MODEST AT MID-AFTN...WILL INCREASE AS PRIMARY

UPR TROUGH OVER THE SRN HIGH PLAINS APPROACHES THE REGION AND LLVL

INCREASE RISK FOR TORNADOES LATE THIS AFTN AND EARLY EVENING.



AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL

SURFACE AND ALOFT TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE

WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO

500. MEAN STORM MOTION VECTOR 24035.





...RACY

