

341 

WWUS20 KWNS 170127

SEL3

SPC WW 170127

ILZ000-MOZ000-170700-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 403

NWS STORM PREDICTION CENTER NORMAN OK

825 PM CDT SAT JUN 16 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL ILLINOIS

       EASTERN MISSOURI



EFFECTIVE THIS SATURDAY NIGHT AND SUNDAY MORNING FROM 825 PM

UNTIL 200 AM CDT.



HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 75

MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 70

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 35 MILES NORTHWEST

OF SAINT LOUIS MISSOURI TO 30 MILES EAST NORTHEAST OF MATTOON

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 401...WW 402...



DISCUSSION...LIFT ALONG LEADING EDGE OF MATURE MCS COLD POOL IS

EXPECTED TO CONTINUE TO SUPPORT VIGOROUS DEEP CONVECTION SPREADING

EAST ACROSS THE STL AREA AND INTO CNTRL IL THROUGH THE LATE EVENING.

AIR MASS AHEAD OF THIS CONVECTION WARMED CONSIDERABLY THROUGH THE

DAY WITH TEMPS IN MOST AREAS ONLY DROPPING UNDER 90F IN THE LAST

HOUR. GIVEN THE ANTECEDENT STEEP LOW LEVEL LAPSE RATES AND

SUBSTANTIAL PRECIPITATION ACCOMPANYING THE ADVANCING MCS...AT LEAST

A LOCALIZED DAMAGING WIND THREAT SHOULD ENSUE AS STORMS SPREAD

ACROSS THE REGION TONIGHT. MID LEVEL JET STREAK OF ABOUT 40-50 KT

MAY ALSO AID OCCASIONALLY BETTER CELLULAR DEVELOPMENT...EITHER AHEAD

OF OR EMBEDDED IN THE QLCS. WHEN COMBINED WITH POCKETS OF STEEPER

MID LEVEL LAPSE RATES...THIS CONVECTION COULD POSE A THREAT OF

ISOLATED LARGE HAIL.



AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT

TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 65

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM

MOTION VECTOR 27035.





...CARBIN

