

984 

WWUS20 KWNS 171925

SEL2

SPC WW 171925

NEZ000-SDZ000-180300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 462

NWS STORM PREDICTION CENTER NORMAN OK

125 PM MDT SUN AUG 17 2014



THE NWS STORM PREDICTION CENTER HAS ISSUED A



* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

  NORTHERN AND CENTRAL NEBRASKA

  WESTERN AND SOUTH CENTRAL SOUTH DAKOTA



* EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 125 PM UNTIL

  900 PM MDT.



* PRIMARY THREATS INCLUDE...

  SCATTERED LARGE HAIL LIKELY WITH ISOLATED VERY LARGE HAIL EVENTS

    TO 2 INCHES IN DIAMETER POSSIBLE

  SCATTERED DAMAGING WIND GUSTS TO 70 MPH POSSIBLE



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 70

STATUTE MILES EAST AND WEST OF A LINE FROM 25 MILES EAST

NORTHEAST OF BUFFALO SOUTH DAKOTA TO 35 MILES SOUTH OF BROKEN BOW

NEBRASKA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU2).



PRECAUTIONARY/PREPAREDNESS ACTIONS...



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.



&&



DISCUSSION...STORMS ARE INCREASING FROM EXTREME SRN SD INTO FAR NRN

NEB AS AN OUTFLOW BOUNDARY INTERSECTS A LOW-LEVEL MOISTURE

FEED...WHILE ADDITIONAL STORMS ARE DEVELOPING OVER THE BLACK HILLS

AND INTO FAR NWRN SD.  THE AIR MASS IS DESTABILIZING OVER WRN SD IN

THE WAKE OF EARLIER STORMS...WITH STRONG INSTABILITY NOTED SWD INTO

NEB WHERE MLCAPE REACHES 2500-3000 J/KG.  SUFFICIENT VERTICAL SHEAR

/30-40 KT IN THE LOWEST 6 KM AGL/ OVER THE AREA IN ADVANCE OF A

SUBTLE SHORT WAVE TROUGH ADVANCING EWD ACROSS MT AND WY WILL ENHANCE

SEVERE POTENTIAL.  STRONGER STORMS INCLUDING A FEW SUPERCELLS WILL

BE CAPABLE OF PRODUCING LARGE HAIL AND DAMAGING WIND GUSTS...WITH

THE THREAT SPREADING SEWD THROUGH THE EVENING HOURS.



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 500. MEAN STORM

MOTION VECTOR 28020.





...WEISS



381 

WWUS20 KWNS 171925

SEL2

SPC WW 171925

NEZ000-SDZ000-180300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 462

NWS STORM PREDICTION CENTER NORMAN OK

125 PM MDT SUN AUG 17 2014



THE NWS STORM PREDICTION CENTER HAS ISSUED A



* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

  NORTHERN AND CENTRAL NEBRASKA

  WESTERN AND SOUTH CENTRAL SOUTH DAKOTA



* EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 125 PM UNTIL

  900 PM MDT.



* PRIMARY THREATS INCLUDE...

  SCATTERED LARGE HAIL LIKELY WITH ISOLATED VERY LARGE HAIL EVENTS

    TO 2 INCHES IN DIAMETER POSSIBLE

  SCATTERED DAMAGING WIND GUSTS TO 70 MPH POSSIBLE



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 70

STATUTE MILES EAST AND WEST OF A LINE FROM 25 MILES EAST

NORTHEAST OF BUFFALO SOUTH DAKOTA TO 35 MILES SOUTH OF BROKEN BOW

NEBRASKA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU2).



PRECAUTIONARY/PREPAREDNESS ACTIONS...



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.



&&



DISCUSSION...STORMS ARE INCREASING FROM EXTREME SRN SD INTO FAR NRN

NEB AS AN OUTFLOW BOUNDARY INTERSECTS A LOW-LEVEL MOISTURE

FEED...WHILE ADDITIONAL STORMS ARE DEVELOPING OVER THE BLACK HILLS

AND INTO FAR NWRN SD.  THE AIR MASS IS DESTABILIZING OVER WRN SD IN

THE WAKE OF EARLIER STORMS...WITH STRONG INSTABILITY NOTED SWD INTO

NEB WHERE MLCAPE REACHES 2500-3000 J/KG.  SUFFICIENT VERTICAL SHEAR

/30-40 KT IN THE LOWEST 6 KM AGL/ OVER THE AREA IN ADVANCE OF A

SUBTLE SHORT WAVE TROUGH ADVANCING EWD ACROSS MT AND WY WILL ENHANCE

SEVERE POTENTIAL.  STRONGER STORMS INCLUDING A FEW SUPERCELLS WILL

BE CAPABLE OF PRODUCING LARGE HAIL AND DAMAGING WIND GUSTS...WITH

THE THREAT SPREADING SEWD THROUGH THE EVENING HOURS.



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 500. MEAN STORM

MOTION VECTOR 28020.





...WEISS

