

357 

WWUS20 KWNS 162007

SEL1

SPC WW 162007

NEZ000-170300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 621

NWS STORM PREDICTION CENTER NORMAN OK

310 PM CDT MON AUG 16 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHERN NEBRASKA



EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 310 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 35

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 40 MILES NORTH

NORTHWEST OF MULLEN NEBRASKA TO 45 MILES EAST NORTHEAST OF

COLUMBUS NEBRASKA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU1).



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 619...WW 620...



DISCUSSION...A COUPLE OF SUPERCELLS HAVE DEVELOPED THIS AFTERNOON

ALONG A WNW-ESE ORIENTED LOW-LEVEL BAROCLINIC ZONE.  WHILE AMBIENT

AIR MASS IS NOT PARTICULARLY UNSTABLE...THE PRESENCE OF STEEP

LOW-LEVEL LAPSE RATES AND 40-50 KT OF DEEP NWLY SHEAR WILL REMAIN

SUPPORTIVE OF ORGANIZED SEVERE STORMS THROUGH THE REMAINDER OF THE

EVENING.



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 29030.





...MEAD

