Flooding in South Dakota, June 1 to 30, 2001

AREA FORECAST DISCUSSION FOR CENTRAL/NORTHCENTRAL AND NORTHEAST
SOUTH DAKOTA AND WEST CENTRAL MINNESOTA
NATIONAL WEATHER SERVICE ABERDEEN SD
338 PM CDT THU MAY 31 2001

VERY LITTLE DIFFERENCE IN THE MDLS THROUGH THIS FORECAST. FOR
TONIGHT...MDLS SHOW A STRONG 50H UPPER LOW OVER CANADA SLIDING SOUTH
INTO THE UPPER MIDWEST WITH THE FIRST STRONG S/W SWEEPING SE ACROSS
NE SD AND WC MN. THIS S/W WILL ALSO FORCE A COLD FRONT SE ACROSS THE
CWA. THE COLD FRONT LATE THIS AFTN WAS SITUATED ACROSS C AND NC SD
JUST TO THE W OF PIR AND MBG. WITH MOISTURE CONVERGENCE ALONG THIS
COLD FRONT AND DWPTS IN THE MID TO UPPER 50S...LIS HAVE LOWERED TO
-4 TO -6 WITH CAPES OF 1000 TO 1500 J/KG ACROSS THE CWA LATE THIS
AFTN. SCT TSRAS ALONG AND AHEAD OF THIS COLD FRONT WILL END ACROSS C
AND NC SD EARLY AND END BY MIDNIGHT ACROSS NE SD AND WC MN. MUCH
DRIER AND STABLE AIR WILL MOVE IN BEHIND THE COLD FRONT THROUGH THE
EVENING. OTHERWISE...S WINDS WILL BECOME NW. SKIES S/B CLEAR TO P/C
THROUGH THE NIGHT. TEMPS SHOULD FALL INTO THE 40 TO 50 DEGREE RANGE
BY FRI MRNG.

ON FRI AS THE BIG UPPER LOW ROLLS OVER THE AREA...THE SECOND STRONG
S/W WILL SWING S ACROSS THE CWA THROUGH THE DAY. WITH PLENTY OF MEAN
RH AND LIFT WITH THIS S/W...EXPECT SKIES TO BECOME MOSTLY CLOUDY
OVER MUCH OF THE CWA...EXCEPT FOR C SD. ALONG WITH THE CLOUDS SHOULD
ALSO COME SCT SHRAS...ESPECIALLY ACROSS NE SD AND WC MN. WITH LOW
85H TEMPS FOR THIS TIME OF YEAR...IT WILL MIX OUT TO BE A COOL DAY
ACROSS THE CWA WITH TEMPS MAINLY IN THE 60S. IT WILL ALSO BECOME
WINDY AS THE MDLS SHOW 925MB WINDS OF 25 KNOTS ACROSS THE CWA.

FOR FRI NIGHT...THE 50H UPPER LOW MOVES AWAY FROM THE CWA AS THE
MEAN RH DECREASES AND SUBSIDENCE MOVES IN. THEREFORE...LOOK FOR THE
SCT SHRAS TO END ACROSS NE SD AND WC MN DURING THE EVENING ALONG
WITH THE LOW CLOUDS DISSIPATING AS THE SUN SETS. IT WILL ALSO BE
WINDY ACROSS THE CWA THROUGH SUNSET. WITH CLEARING SKIES...TEMPS
SHOULD FALL INTO THE 40S BY SAT MRNG.

SAT...WILL BE A DRY DAY ACROSS THE CWA WITH SFC HIGH PRES IN CONTROL
ALONG WITH MUCH LESS WIND. TEMPS SHOULD BE ABOUT 5 TO 10 DEGREES
WARMER THAN THOSE ON FRI.

ON SAT NIGHT...THE AVN SHOWS SFC HIGH PRES SLIDING E WITH A S/W
MOVING IN FROM THE WEST ALONG WITH INCREASING MEAN RH.
THEREFORE...SKIES SHOULD BECOME MOSTLY CLOUDY ACROSS THE CWA WITH A
CHANCE OF SHRAS AND TSRAS AFTER MIDNIGHT ACROSS C AND NC SD. THE AVN
PUTS OUT SOME DECENT QPF ACROSS C AND INTO NC SD BY SUN MRNG. TEMPS
WILL NOT FALL OFF AS MUCH WITH THE CLOUD COVER AND HIGHER DWPTS
ACROSS THE CWA.

.EXTENDED FORECAST DISCUSSION...
EXTENDED MODELS IN FAIR AGREEMENT THIS AFTERNOON. AFTER ANALYZING
THE MODELS AND THE ENSEMBLES A LITTLE MORE...I DECIDED TO GO WITH
THE AVN/MRF FOR THE FORECAST PACKAGE. A COUPLE OF SHORT WAVES MOVING
THROUGH THE CWA ON SUNDAY AND AGAIN ON MONDAY. THESE SYSTEMS ALONG
WITH THEIR ASSOCIATED SURFACE FRONTS WILL HAVE ENOUGH LIFT AND
MOISTURE TO PRODUCE SHOWERS AND THUNDERSTORMS AT THAT TIME. HIGH
PRESSURE WILL FOLLOW BRINGING DRY WEATHER CONDITIONS THROUGH THE
MIDDLE PART OF THE WEEK. TEMPS WILL BE A LITTLE COOL ON SUNDAY AND
MONDAY BUT WILL WARM BACK TO NEAR NORMAL BY THURSDAY. THE GUIDANCE
TEMPS APPEAR TO BE REASONABLE AND WILL USE A BLEND BETWEEN THE FMR
AND MEX.

.ABR...NONE

MOHR/SALMONS