

148 

WWUS20 KWNS 101848

SEL0

SPC WW 101848

ILZ000-MOZ000-110200-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 90

NWS STORM PREDICTION CENTER NORMAN OK

150 PM CDT WED APR 10 2013



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       SOUTHERN ILLINOIS

       SOUTH CENTRAL AND SOUTHEAST MISSOURI



EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 150 PM UNTIL

900 PM CDT.



TORNADOES...HAIL TO 2.5 INCHES IN DIAMETER...THUNDERSTORM WIND

GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE

AREAS.



THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 80 STATUTE

MILES EAST AND WEST OF A LINE FROM 25 MILES NORTHEAST OF SCOTT

AFB ILLINOIS TO 35 MILES EAST SOUTHEAST OF WEST PLAINS MISSOURI.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU0).



REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR

TORNADOES AND 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.



OTHER WATCH INFORMATION...CONTINUE...WW 88...WW 89...



DISCUSSION...SURFACE HEATING/DESTABILIZATION ACROSS SRN/ERN MO IS

CONTRIBUTING TO MODERATE INSTABILITY IN THE WARM SECTOR...WITH A

WEAKENING CAP AND INCREASING PROBABILITY FOR THUNDERSTORM INITIATION

IN THE NEXT COUPLE OF HOURS.  GIVEN THE MODERATE INSTABILITY AND MID

60S BOUNDARY LAYER DEWPOINTS...AN INCREASE IN VERTICAL SHEAR

/ALREADY NOTED IN THE VWP FROM SAINT LOUIS/ WILL RESULT IN AN

INCREASING RISK FOR SUPERCELLS WITH TORNADOES AND LARGE HAIL.  LATER

THIS AFTERNOON/EVENING...CONVECTION SHOULD EVOLVE INTO MORE OF A

LINE ALONG THE COLD FRONT IN MO...WITH A CONTINUED RISK FOR EMBEDDED

CIRCULATIONS AND DAMAGING WINDS.



AVIATION...TORNADOES AND 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 23040.





...THOMPSON

