

179 

WWUS20 KWNS 201936

SEL4

SPC WW 201936

KSZ000-NEZ000-OKZ000-210300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 314

NWS STORM PREDICTION CENTER NORMAN OK

235 PM CDT FRI MAY 20 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL KANSAS

       CENTRAL AND EASTERN NEBRASKA

       NORTHWEST OKLAHOMA



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 235 PM UNTIL

1000 PM 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 65

STATUTE MILES EAST AND WEST OF A LINE FROM 20 MILES NORTH

NORTHEAST OF GRAND ISLAND NEBRASKA TO 40 MILES SOUTH OF ALVA

OKLAHOMA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU4).



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 312...WW 313...



DISCUSSION...TSTMS ARE CURRENTLY DEVELOPING ALONG A COLD FRONT WHICH

STRETCHES FROM CNTRL NEB SWD INTO WRN OK.  FORCING FOR ASCENT

ATTENDANT TO VORTICITY MAXIMUM PIVOTING NNEWD ACROSS THE REGION

SHOULD SUPPORT AN INCREASE IN STORM COVERAGE AND INTENSITY THROUGH

THE REMAINDER OF THE AFTERNOON.  AMBIENT WARM SECTOR AIR MASS IS

CHARACTERIZED BY A GRADUALLY WARMING BOUNDARY LAYER WITH DEWPOINTS

IN THE UPPER 50S TO LOWER 60S...RESULTING IN MLCAPE VALUES OF

500-1000 J/KG.  GIVEN THE SUPERPOSITION OF MID AND UPPER-LEVEL JET

AXES ALONG INSTABILITY AXIS...SETUP WILL FAVOR THE DEVELOPMENT OF

ORGANIZED STORMS...INCLUDING SUPERCELLS AND LINE SEGMENTS CAPABLE OF

HAIL AND LOCALLY DAMAGING WIND GUSTS.



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 400. MEAN STORM

MOTION VECTOR 21025.





...MEAD

