

641 

WWUS20 KWNS 012013

SEL2

SPC WW 012013

OKZ000-TXZ000-020300-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 222

NWS STORM PREDICTION CENTER NORMAN OK

310 PM CDT FRI MAY 1 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       SOUTHERN OKLAHOMA

       NORTHWEST TEXAS



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 310 PM UNTIL

1000 PM CDT.



TORNADOES...HAIL TO 3 INCHES IN DIAMETER...THUNDERSTORM WIND

GUSTS TO 80 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE

AREAS.



THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 60 STATUTE

MILES NORTH AND SOUTH OF A LINE FROM 135 MILES WEST SOUTHWEST OF

WICHITA FALLS TEXAS TO 45 MILES NORTH NORTHEAST OF DURANT

OKLAHOMA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU2).



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...CONTINUE...WW 221...



DISCUSSION...STRONG INSTABILITY IN THE PRESENCE OF PERSISTENT LOW

LEVEL CONVERGENCE ALONG ADVANCING FRONT AND OUTFLOW BOUNDARIES HAS

LED TO  A VOLATILE SEVERE WEATHER SITUATION ACROSS NWRN TX AND

ADJACENT AREAS OF THE RED RIVER IN OK THIS AFTERNOON. EXPECT STORM

INITIATION SHORTLY NEAR DRYLINE/FRONT INTERSECTION IN WRN SECTIONS

OF THE WATCH. MLCAPE OF 2500-3000 J PER KG WILL FUEL POTENT UPDRAFTS

ONCE INHIBITION IS OVERCOME. CELLS SHOULD QUICKLY ACQUIRE SUPERCELL

CHARACTERISTICS WITH JUST ENOUGH DEEP-LAYER SHEAR TO SUPPORT

PERSISTENT UPDRAFT ROTATION. VERY LARGE HAIL SHOULD BE ONE OF THE

MORE SIGNIFICANT THREATS WITH THIS DEVELOPMENT GIVEN MAGNITUDE OF

CAPE AND STRENGTH OF UPDRAFTS. TORNADO POTENTIAL WILL BE MODULATED

BY OVERALL STORM EVOLUTION. HOWEVER...CELLS TRACKING NEAR THE FRONT

AND OUTFLOW WILL HAVE ENHANCED LOW LEVEL SHEAR/VORTICITY AVAILABLE

TO THEM AND COULD END UP PRODUCING A COUPLE OF TORNADOES.

EVENTUALLY...CELL MERGERS MAY SUPPORT UPSCALE EVOLUTION INTO A

SEVERE MCS TRACKING EWD/SEWD NEAR AND SOUTH OF THE RED RIVER THROUGH

THIS EVENING.



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

SURFACE AND ALOFT TO 3 INCHES. EXTREME TURBULENCE AND SURFACE

WIND GUSTS TO 70 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO

500. MEAN STORM MOTION VECTOR 29015.





...CARBIN/DARROW

