

067 

WWUS20 KWNS 161807

SEL2

SPC WW 161807

ILZ000-MOZ000-170100-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 582

NWS STORM PREDICTION CENTER NORMAN OK

105 PM CDT THU AUG 16 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       SOUTHERN ILLINOIS

       SOUTHERN AND SOUTHEAST MISSOURI



EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 105 PM UNTIL

800 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 100

STATUTE MILES EAST AND WEST OF A LINE FROM 50 MILES WEST

SOUTHWEST OF WEST PLAINS MISSOURI TO 40 MILES NORTH NORTHWEST OF

DECATUR ILLINOIS.  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...STRONG HEATING AHEAD OF A CONVECTIVE OUTFLOW BOUNDARY

AND ADVANCING COLD FRONT HAS ALLOWED DEEP CONVECTION TO ERUPT FROM

THE OZARKS NWD AND INTO ERN MO AND EWD INTO IL EARLY THIS AFTERNOON.

EXPECT THAT ADDITIONAL STORMS WILL DEVELOP ACROSS THESE REGIONS

THROUGH THE LATER AFTERNOON AS THE FRONT CONTINUES TO PROVIDE

ADEQUATE FORCING IN A STRONGLY UNSTABLE AIRMASS. STRONGER DEEP-LAYER

FLOW WILL REMAIN ACROSS NRN PARTS OF THE WATCH...PRIMARILY IN

IL...WHERE SHEAR COULD SUPPORT LONGER-LIVED ORGANIZED CELLS CAPABLE

OF BOTH LARGE HAIL AND HIGH WINDS. FARTHER SOUTH INTO MO...FRONTAL

CONVERGENCE SHOULD HELP TO FOCUS STRONGER CELLS IN A GENERALLY

WEAKER KINEMATIC REGIME. HOWEVER...INSTABILITY AND HOT BOUNDARY

LAYER ACROSS THIS PART OF THE WATCH AREA WILL CONTRIBUTE TO AN

INCREASING DAMAGING WIND HAZARD AS STORMS INCREASE IN COVERAGE

THROUGH THE REST OF THE AFTERNOON.



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 550. MEAN STORM

MOTION VECTOR 26025.





...CARBIN

