Severe Thunderstorm Warning 112, NWS Aberdeen, SD

AREA FORECAST DISCUSSION FOR CENTRAL/NORTHCENTRAL AND NORTHEAST
SOUTH DAKOTA AND WEST CENTRAL MINNESOTA
NATIONAL WEATHER SERVICE ABERDEEN SD
335 PM CDT THU AUG 3 2000

WARM FRONT NOW EXTENDS FROM THE WYOMING/MONTANA/SOUTH DAKOTA BORDER
TO JUST NORTH OF PIERRE TO NEAR YANKTON. SPC ALREADY HAS ISSUED A
DISCUSSION INDICATING THE POTENTIAL FOR SEVERE WEATHER ACROSS NORTH
CENTRAL SOUTH DAKOTA OVER THE NEXT FEW HOURS JUST NORTH OF THIS
BOUNDARY. WILL CONTINUE TO MONITOR THIS AREA AS SHOWERS AND
THUNDERSTORMS ARE BEGINNING TO DEVELOP OVER CORSON COUNTY.
MSAS ANALYSIS INDICATED LIFTED INDICIES OF -4C TO -9C OVER THE CWA
WITH THE GREATEST PRESSURE FALLS OVER CENTRAL AND NORTH CENTRAL
SOUTH DAKOTA. ALSO NOTICED DRYER AIR MASS MOVING INTO SOUTHWESTERN
SOUTH DAKOTA OVER THE LAST FEW HOURS.

FOR TONIGHT...THE COMBINATION OF AN UPPER LEVEL DISTURBANCE...
SURFACE WARM FRONT ACROSS SOUTH DAKOTA...AND LOW PRESSURE AND
ASSOCIATED SURFACE COLD FRONT MOVING INTO SOUTH DAKOTA WILL BE THE
MECHANISM FOR SHOWER AND THUNDERSTORM ACTIVITY TONIGHT AND ACROSS
THE EAST SATURDAY MORNING. FOR TONIGHT...850MB LOW LEVEL JET WILL
KICK IN AND TAKE AIM FOR NORTHEASTERN SOUTH DAKOTA. ETA/AVN MODELS
INDICATED PRECIPITABLE WATER VALUES INCREASING TO NEAR 2 INCHES IN
THE EAST TONIGHT. SEVERAL FACTORS ARE COMING IN TO PLAY FOR HEAVY
RAIN AND THE POTENTIAL FOR FLASH FLOODING. FIRST...AREAS ACROSS
PARTS OF NORTHEASTERN SOUTH DAKOTA RECEIVED ONE TO TWO INCHES OF
RAIN LAST NIGHT. ALSO...MAXIMUM RAINFALL USUALLY OCCURS JUST
NORTHEAST OF THE THETA-E RIDGE WHICH IS EXPECTED TO BE CENTERED
ACROSS EASTERN SOUTH DAKOTA TONIGHT. MAXIMUM RAINFALL USUALLY OCCURS
DURING THE SUMMER SOUTH OF THE WARM FRONT (IS EXPECTED TO MOVE
NORTHWARD TONIGHT). THESE FACTORS WILL LEAD TO THE ISSUANCE OF A
FLASH FLOOD WATCH FOR PORTIONS OF NORTHEASTERN SOUTH DAKOTA AND BIG
STONE AND TRAVERSE COUNTIES IN MINNESOTA.

FOR SATURDAY...SHOWERS AND THUNDERSTORMS WILL END ACROSS THE EAST
DURING THE MORNING. ETA/NGM TIME CROSS SECTIONS STILL SHOW A LOT OF
LOW LEVEL MOISTURE IN THE NORTHEAST THROUGHOUT THE AFTERNOON. WILL
WORD FORECAST MOSTLY CLOUDY IN THE NORTHEAST AND PARTLY SUNNY
ELSEWHERE. TEMPERATURES WILL BE TRICKY AND VARY WIDELY ACROSS THE
CWA DUE TO THE AMOUNT OF SUNSHINE AND THE PIERRE EFFECT. WENT AT OR
JUST BELOW GUIDANCE IN THE EAST AND AT OR JUST ABOVE GUIDANCE IN THE
PIERRE GROUP. DID A SMALL CHANCE FOR THUNDERSTORMS IN THE MOBRIDGE
GROUP LATE IN THE DAY AS THE NEXT SHORTWAVES DROPS SOUTHEAST INTO
THE NORTHERN PLAINS.

FOR SATURDAY NIGHT AND SUNDAY...SHORTWAVE DROPS SOUTHEASTWARD ACROSS
THE NORTHERN PLAINS AND INTO THE GREAT LAKES REGION. WILL ADD A
CHANCE OF SHOWERS AND THUNDERSTORMS ACROSS THE ENTIRE CWA FOR
SATURDAY EVENING IN THE MOBRIDGE GROUP AND THE ENTIRE PERIOD
ELSEWHERE. EXPECTING THE GREATEST CHANCES FOR RAIN IN THE NORTHEAST.
HIGH PRESSURE BUILDS INTO THE REGION ON SUNDAY. GUIDANCE LOOKED
REASONABLE FOR SATURDAY NIGHT AND SUNDAY WAS FOLLOWED.

.ABR...FLASH FLOOD WATCH IS IN EFFECT FOR PORTIONS OF NORTHEAST
       SOUTH DAKOTA AND BIG STONE AND TRAVERSE COUNTIES IN
       MINNESOTA.

ECKBERG/KEEFE
N

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ABERDEEN SD
635 PM CDT FRI AUG 4 2000

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

0600 PM    EAGLE BUTTE               SD   .75 INCH HAIL
08/04/00   DEWEY

JH

N

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ABERDEEN SD
734 PM CDT FRI AUG 4 2000

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

0710 PM    6 W RIDGEVIEW             SD   .88 INCH HAIL
08/04/00   DEWEY                          NICKLE SIZE HAIL.

JH

N

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ABERDEEN SD
828 PM CDT FRI AUG 4 2000

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

0800 PM    MISSION RIDGE             SD   1.75 INCH HAIL
08/04/00   STANLEY                        GOLF BALL SIZE HAIL COVERED
                                          THE GROUND.  1.4 INCHES OF
                                          RAIN.

JH

N