SPC MESOSCALE DISCUSSION 1216 FOR SERN SD / SWRN MN / NWRN IA
CONCERNING...SEVERE THUNDERSTORM POTENTIAL...

VALID 171957Z - 172200Z

ELEVATED STRONG/SEVERE STORMS JUST W OF ABR WILL CONTINUE TO TRACK
TO THE SE INTO ERN SD WITH THE POTENTIAL OF PRODUCING LARGE HAIL. 
ADDITIONAL STORMS ARE EXPECTED TO DEVELOP ALONG THE WARM FRONT OVER
SERN SD INTO NWRN IA/SWRN MN IN THE NEXT 1-2 HOURS.  THESE STORMS
SHOULD BECOME SEVERE RAPIDLY WITH THE POTENTIAL OF PRODUCING VERY
LARGE HAIL...DAMAGING WINDS AND A FEW TORNADOES.  WW WILL BE ISSUED
SHORTLY.

A STRONG/SEVERE THUNDERSTORM OVER FAULK AND EDMUNDS COUNTIES SD IS
TRACKING TO THE SE AT 35 KT.  VISIBLE SATELLITE IMAGERY SHOWS
FURTHER CU/TCU DEVELOPING SWWD FROM THIS STORM INTO POTTER COUNTY. 
ADDITIONAL CU IS DEVELOPING ALONG A SURFACE WARM FRONT OVER SERN
SD.  THE AIRMASS ALONG AND SOUTH OF THIS WARM FRONT HAS CONTINUED
TO DESTABILIZE THIS AFTERNOON WITH VERY UNSTABLE 100 MB MLCAPE
VALUES RANGING FROM 2500-3500 J/KG FROM SOUTH CENTRAL SD TO EXTREME
NWRN IA.  500 MB WLY SPEED MAX AROUND 50 KT OVER SD WITH SSELY LOW-
LEVEL FLOW ARE RESULTING IN DEEP LAYER AND DIRECTIONAL SHEAR
SUPPORTIVE OF ORGANIZED STORMS/SUPERCELLS.  

..PETERS.. 06/17/01