Severe Thunderstorm Warning 187, NWS Aberdeen, SD

AREA FORECAST DISCUSSION FOR CENTRAL/N-EAST SD AND W-CENTRAL MN
NATIONAL WEATHER SERVICE ABERDEEN SD
346 PM CDT WED AUG 28 2002

MAIN FORECAST CHALLENGE WILL BE COVERAGE AND SEVERITY OF CURRENT
CONVECTION ACROSS CWA...AND HOW LONG IT WILL PERSIST THROUGH
TONIGHT.

CURRENTLY HAVE A S/W MOVG SLOWLY ACROSS THE STATE THROUGH TONIGHT.
WITH DAYTIME HEATING AND LOW LVL MOISTURE IN PLACE...HAVE A FAIRLY
UNSTABLE ATMOSPHERE. 12Z SOUNDING SHOWS LIFTED INDICES AROUND -8 AND
APPROX 3000 J/KG CAPE...WITH ETA 00Z SOUNDING ALSO SHOWING SIMILAR
VALUES. WIND PROFILE CONTINUES TO BE RATHER WEAK AS IT HAS IN THE
PAST FEW DAYS...WITH 850MB WINDS OUT OF THE SSE AT ONLY 15KTS AND
500MB WINDS AROUND 10KTS. ALSO HAVE STATIONARY BOUNDARY IN PLACE
ACROSS REGION...STRETCHING FROM WESTERN SD NORTHEASTWARD INTO EAST
CENTRAL ND AND NORTHERN MN. FEEL TSRA THREAT WILL BE SCATTERED WITH
ONLY ISOLATED SEVERE CASES THIS EVENING. FOR TONIGHT...FEEL ISOLATED
SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH THE OVERNIGHT HOURS
AS S/W WORKS IT WAY ACROSS THE STATE. ETA SHOWS NEXT CHANCE FOR
PRECIP BEGINNING LATE THU NIGHT INTO FRI AS NEXT SYSTEM APPROACHES
THE NRN PLAINS. LOOKS LIKE BEST CHANCE COMES DURING THE DAY ON FRI
AS TROUGH MOVES OVER NRN PLAINS. LOW LVL WINDS ALSO PICKUP ON FRI
THROUGHOUT THE DAYTIME AS 850MB JET INCREASES TO 30 TO 35KTS ACROSS
THE DAKOTAS. ALSO SHOW GOOD DYNAMICS ACROSS NE SD SO HAVE INCLUDED
CHANCE OF TSRAS FOR WHOLE CWA ON FRI INTO FRI NIGHT WITH TROUGH MOVG
THROUGH NRN PLAINS. THE ASSOCIATED COOL FRONT LOOKS TO MOVE THROUGH
AREA SAT AM BUT LOOKS AS IF MOST PRECIP ASSOCIATED WITH FRONT WILL
BE NORTH OF CWA INTO ND AND MN...AS A RESULT HAVE KEPT SAT DRY FOR
NOW.  ALBRECHT

.EXTENDED DISCUSSION...
THE TREND OF THE MDLS DURING THE EXTENDED PERIOD SUN-WED IS TO
WEAKEN THE WESTERN UNITED STATES 50H TROUGH THEN GO TO ZONAL FLOW
OR WNW FLOW ALONG THE NORTHERN PART OF THE U.S./SOUTHERN CANADA
FOLLOWED BY A DEEPENING NE PACIFIC TROUGH AND A BUILDING DOWNSTREAM
RIDGE OVER THE CENTRAL UNITED STATES. WITH THE MDLS HAVING THEIR
USUAL DIFFICULT TIME IN AGREEING ON THE TIMING AND THE STRENGTH OF
S/WS AND FRONTS WITH A TRANSITIONING PATTERN LIKE THIS...WILL LEAVE
IT DRY THROUGH THE FORECAST. IT ALSO LOOKS LIKE IT WILL WARM UP
THROUGH THE PERIOD WITH ABOVE NORMAL TEMPS.  MOHR

.ABR...NONE.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ABERDEEN, SD
451 PM CDT WED AUG 28 2002

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

0325 PM    4 WNW NORTHVILLE          SD   1.00 INCH HAIL
08/28/02   SPINK

0345 PM    5 NW ATHOL                SD   .75 INCH HAIL
08/28/02   SPINK

0425 PM    8 S GROTON                SD   1.00 INCH HAIL
08/28/02   BROWN

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ABERDEEN, SD
511 PM CDT WED AUG 28 2002

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

0455 PM    4 SSW ROSHOLT             SD   1.00 INCH HAIL
08/28/02   ROBERTS