

000 

WWUS20 KWNS 201827

SEL2

SPC WW 201827

NDZ000-SDZ000-210200-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 152

NWS STORM PREDICTION CENTER NORMAN OK

125 PM CDT FRI APR 20 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       SOUTHEASTERN NORTH DAKOTA

       A LARGE PART OF SOUTH DAKOTA



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 125 PM UNTIL 900

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 65

STATUTE MILES EAST AND WEST OF A LINE FROM 80 MILES NORTH

NORTHEAST OF ABERDEEN SOUTH DAKOTA TO 75 MILES SOUTHWEST OF

CHAMBERLAIN SOUTH DAKOTA.  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...WARM ADVECTION STORMS EXPECTED TO STRENGTHEN INVOF

FRONT STALLED SW/NE ACROSS SD.  STEEP MID LEVEL LAPSE

RATES...ESPECIALLY FROM CNTRL SD NWD...AND INCREASING LOW LEVEL

MOISTURE INFLOW SHOULD SUPPORT POTENTIAL FOR LARGE HAIL AND POSSIBLY

HIGH WIND GIVEN 40+ KT CLOUD LAYER SHEAR DESPITE SLIGHTLY ELEVATED

NATURE OF STORMS.



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 450. MEAN STORM

MOTION VECTOR 21030.





...CORFIDI

