

001 

WWUS20 KWNS 190226

SEL3

SPC WW 190226

IAZ000-ILZ000-MOZ000-191000-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 673

NWS STORM PREDICTION CENTER NORMAN OK

930 PM CDT SAT SEP 18 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       EXTREME SOUTH CENTRAL IOWA

       EXTREME WEST CENTRAL ILLINOIS

       NORTHERN MISSOURI



EFFECTIVE THIS SATURDAY NIGHT AND SUNDAY MORNING FROM 930 PM

UNTIL 500 AM 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 40

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 55 MILES WEST

SOUTHWEST OF LAMONI IOWA TO 40 MILES SOUTHEAST OF QUINCY

ILLINOIS.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU3).



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 672...



DISCUSSION...ELEVATED THUNDERSTORMS WILL LIKELY INCREASE IN COVERAGE

OVERNIGHT AS LOW-LEVEL WAA INCREASES ABOVE THE SURFACE COLD FRONT

ACROSS NRN MO.  MUCAPE OF 1500-2000 J/KG BASED NEAR 850 MB AND

EFFECTIVE BULK SHEAR IN EXCESS OF 50 KT WILL BE SUPPORTIVE OF

ELEVATED SUPERCELLS CAPABLE OF PRODUCING LARGE HAIL.  THE CONVECTION

FARTHER S IN MO IS EXPECTED TO SLOWLY WEAKEN IN THE NEXT 1-2

HOURS...WITH A LIKEWISE REDUCTION IN THE HAIL/WIND THREAT.



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.





...THOMPSON

