Severe Thunderstorm Warning 177, NWS Aberdeen, SD

AREA FORECAST DISCUSSION FOR CENTRAL/N-EAST SD AND W-CENTRAL MN
NATIONAL WEATHER SERVICE ABERDEEN SD
300 PM CDT WED AUG 21 2002

MODELS IN PRETTY GOOD AGREEMENT...WITH JUST SOME MINOR DIFFERENCES
IN PRECIP LOCATION AND AMOUNT. WILL STICK WITH PREVIOUS FORECAST AND
GO WITH THE ETA. MAIN CONCERN WILL BE PRECIPITATION CHANCES TONIGHT
AS A WEAKENING COLD FRONT SLIDES THROUGH CWA. THE ACTIVITY
ASSOCIATED WITH THIS FRONT OVER NORTH DAKOTA HAS BEEN MINIMAL MOST
OF THE DAY...AND AN ABUNDANCE OF CLOUD COVER HAS KEPT TEMPERATURES
DOWN OVER MOST OF THE AREA. WILL KEEP JUST A CHANCE POP GOING FOR
THE AREA WITH THE FRONTAL PASSAGE TONIGHT.

FOR THE REMAINDER OF THE FORECAST PERIOD...HIGH PRESSURE AT THE
SURFACE SETTLES IN OVER THE NORTHERN PLAINS BEHIND THE EXITING FRONT
AND THEN STAYS THERE. A DECENT UPPER LOW WILL SIT AND SPIN OVER THE
PACIFIC NORTHWEST...ALLOWING THE WEAK RIDGE OVER THE PLAINS TO MOVE
VERY LITTLE. WEAK LOW PRESSURE WILL REMAIN OVER THE ROCKIES...WHICH
SHOULD KEEP ANY PRECIPITATION WEST OF THE CWA THROUGH SATURDAY. THE
LOW OVER THE PACIFIC NORTHWEST BECOMES MORE OF AN OPEN TROUGH BY
SATURDAY...WITH A LOBE EXTENDING FROM IT INTO THE WESTERN HIGH
PLAINS BY SATURDAY NIGHT. WENT AHEAD AN THREW IN A SMALL POP FOR THE
FAR WESTERN CWA FOR SATURDAY NIGHT DUE TO THIS.

EXPECT TEMPERATURES TO REMAIN A BIT COOL ON THURSDAY AS SOME OF THE
CLOUD COVER HANGS AROUND BEHIND THE FRONT...BUT MUCH MORE SUN THAN
CLOUDS AFTER THAT...WHICH SHOULD ALLOW TEMPERATURES TO RISE BACK
INTO THE UPPER 70S TO LOWER 80S BY FRIDAY.

.EXTENDED DISCUSSION...

EXTENDED MODELS ARE IN SOME DISAGREEMENT FOR THE EXTENDED PERIOD.
CONFIDENCE IS NOT HIGH THAT THIS WILL BE THE FINAL SOLUTION.  UPPER
FLOW PATTERN IS CHANGING DURING THIS TIME AS A FAIRLY SIGNIFICANT
WEST COAST TROUGH IN THE NORTHERN STREAM FLATTENS THE MIDWEST RIDGE.
PART OF THE ENERGY ASSOCIATED WITH THIS HANGS UP IN THE WEST AND
EVENTUALLY CLOSES OFF JUST OFFSHORE AS NORTHERN PART WEAKENS AS IT
MOVES THROUGH THIS AREA.  STILL MUCH UNCERTAINTY ABOUT TIMING BUT
WILL INTRODUCE A CHANCE OF RAIN SHOWERS AT THE END OF THE PERIOD.
TEMPERATURES LOOK REASONABLE.

.ABR...NONE.

PARKIN/KEEFE

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ABERDEEN, SD
1143 AM CDT WED AUG 21 2002

TIME(CDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

1000 PM    WATERTOWN                 SD   4.00+ INCH HEAVY RAIN
08/20/02   CODINGTON                      BASEMENTS FLOODED AND
                                          SEVERAL ROADS BARRICADED IN
                                          WATERTOWN DUE TO FLOODING

1000 PM    3 NW ALTAMONT             SD   4.6 TO 6 IN HEAVY RAIN
08/20/02   DEUEL                          WATER IN BASEMENT

1000 PM    4 NE CASTLEWOOD           SD   HEAVY RAIN
08/20/02   HAMLIN                         WATER IN BASEMENT

1000 PM    CASTLEWOOD                SD   HEAVY RAIN
08/20/02   HAMLIN                         CONSTRUCTION EQUIPMENT
                                          UNDERWATER AT CONSTRUCTION
                                          SITE

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ABERDEEN, SD
230 PM CDT WED AUG 21 2002

TIME(CDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0145 PM    1 NE HAYS                 SD   0.88 INCH HAIL
08/20/02   STANLEY                        REPORTED BY GENERAL PUBLIC

0345 PM    3 E GOODWIN               SD   1.00 INCH HAIL
08/20/02   DEUEL                          REPORTED BY GENERAL PUBLIC