

531 

WWUS20 KWNS 062236

SEL2

SPC WW 062236

IAZ000-MOZ000-NEZ000-070600-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 732

NWS STORM PREDICTION CENTER NORMAN OK

535 PM CDT SAT AUG 6 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       WESTERN IOWA

       EXTREME NORTHWEST MISSOURI

       CENTRAL AND EASTERN NEBRASKA



EFFECTIVE THIS SATURDAY AFTERNOON AND SUNDAY MORNING FROM 535 PM

UNTIL 100 AM CDT.



HAIL TO 2.5 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 75

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 30 MILES NORTH

NORTHWEST OF GRAND ISLAND NEBRASKA TO 50 MILES NORTH OF LAMONI

IOWA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED

WATCH OUTLINE UPDATE (WOUS64 KWNS WOU2).



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 DEVELOPING OVER SOUTH CENTRAL NEB

ALONG/AHEAD OF A WEAK CONFLUENCE ZONE...WITH ADDITIONAL CELLS

FORMING OVER NORTHEAST NEB ALONG THE SRN EDGE OF STABLE LAYER.

WATER VAPOR IMAGERY SHOWS A SUBTLE PERTURBATION IN THE FLOW MOVING

EWD ACROSS CENTRAL NEB...WITH STRONGER WESTERLY FLOW ALOFT

ASSOCIATED WITH THIS FEATURE. CONSIDERABLE INSTABILITY WITH MLCAPE

OF 2500-3000 J/KG COINCIDENT WITH 30-40 KT DEEP LAYER SHEAR WILL

ENHANCE POTENTIAL FOR SEVERE STORMS TO DEVELOP.  ACTIVITY IS

EXPECTED TO SPREAD EWD THROUGH THE EVENING HOURS WITH THE

POSSIBILITY OF UPSCALE GROWTH INTO A FORWARD-PROPAGATING QLCS LATER

THIS EVENING.



AVIATION...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 550. MEAN STORM

MOTION VECTOR 27025.





...WEISS

