Hail and Damaging Wind in South Dakota, August 16, 2002

AREA FORECAST DISCUSSION FOR CENTRAL/N-EAST SD AND W-CENTRAL MN
NATIONAL WEATHER SERVICE ABERDEEN SD
320 PM CDT FRI AUG 16 2002

MAIN CONCERNS FOR FORECAST ARE CONVECTION AND WIND.  VERY STRONG
SYSTEM EVIDENT IN WV LOOP HEADING QUICKLY ESE INTO NORTHERN PLAINS
LATE THIS AFTERNOON.  ALL PERTINENT MODEL INDICES EXCEPTING SFC
BASED INTABILITY LOOK DECENT AND IN SUPPORT OF SVR OUTBREAK AHEAD OF
ADVANCING FRONTAL BOUNDARY.  STILL AM EXPECTING FAIRLY GOOD BOUNDARY
LAYER MOISTURE TO MAKE IT INTO CWA BEFORE FROPA AND THEREFORE WILL
KEEP HIGH POPS GOING.  NEXT PROBLEM IS WIND BEHIND FRONT.  MAJOR
PRESSURE RISES AND VERY TIGHT GRADIENT ALONG WITH STEEP LAPSE RATES
POINT TO WINDY NIGHT...ESPECIALLY IN THOSE FAVORED AREAS NEAR THE MO
RIVER VALLEY.  8H WINDS UPWARDS 60 KNOTS COULD MIX DOWN OUT THERE.
WILL THEREFORE GO WITH HIGH WIND WARNING WEST CWA AND WIND ADVISORY
EAST.  EVE SHIFT WILL HAVE TO PAY CLOSE ATTENTION TO THIS AND
UPGRADE IF NECESSARY.

REST OF THE FORECAST FAIRLY STRAIGHTFORWARD WITH HIGH SETTLING IN
AND GENERALLY DRY TROP IN PLACE.  WENT CLOSER TO ADIABATIC MIXING
DOWN OF 8H TEMPS FOR SATURDAYS TEMPS AND THEREFORE FELT FWC TEMPS
WERE BETTER FOR HIGHS.  COOLISH SATURDAY NIGHT UNDER HIGH AND THEN
SOME WARMUP FOR SUNDAY.  ANOTHER MID LEVEL WAVE COMES THROUGH SUNDAY
NIGHT AND EARLY MONDAY BUT AT THIS TIME APPEARS THAT AVAILABLE
MOISTURE WILL BE SCANT AND DYNAMICS NOT PARTICULARY GREAT.  WILL KEEP
SAID TIME PERIOD DRY FOR TIME BEING.

TDK

.EXTENDED DISCUSSION...
CONCERN IN THE EXTENDED CONTINUES TO REVOLVE AROUND TUESDAY. AVN EXT
AND ECMWF CONTINUE TO SHOWCASE ANOTHER SYSTEM TO DROP SOUTHEASTWARD
INTO NORTHERN PLAINS ON TUESDAY...DRAGGING A COLD FRONT THROUGH CWA
BY LATE TUESDAY/EARLY WEDNESDAY. THIS SYSTEM SHOULD SEE ENOUGH
RETURN FLOW MOISTURE TO WORK WITH AND WILL CONTINUE TO CARRY
CONVECTIVE CHANCES TUESDAY. WILL LEAVE WEDNESDAY DRY FOR THE MOMENT
AND SEE IF MODELS CONTINUE TO SLOW THE PASSAGE OF THE COLD FRONT
MORE TO WEDNESDAY. THURSDAY SHOULD BE A QUIET WEATHER DAY BETWEEN
SYSTEMS. THE ONLY QUESTION REMAINING FOR DAY 7 WILL BE WHETHER OR
NOT AVN EXT OVERLY ZEALOUS ATTEMPT TO PUMP UP WEST COAST RIDGE WILL
PAN OUT. IF THIS IS THE CASE...EXPECT THAT UPPER LEVEL TROUGH WILL
MIGRATE FROM WEST COAST TO NORTH CENTRAL PLAINS AND INTRODUCE COOLER
TEMPERATURES. NOT REAL CLEAR NOW ON STRENGTH OF COOL FRONT/SURFACE
TROUGH PASSAGE ON FRIDAY...SO WILL LEAVE FRIDAY DRY AND DUMBED DOWN
TOWARD MEX GUIDANCE TEMPERATURE NUMBERS.

DORN

.ABR...HIGH WIND WARNING TONIGHT FOR ADJACENT MO RIVER COUNTIES.
       WIND ADVISORY OVERNIGHT FOR EASTERN CWA.