Severe Thunderstorm Warning 12, NWS Aberdeen, SD

AREA FORECAST DISCUSSION FOR CENTRAL/NORTHCENTRAL AND NORTHEAST
SOUTH DAKOTA AND WEST CENTRAL MINNESOTA
NATIONAL WEATHER SERVICE ABERDEEN SD
320 PM CDT MON MAY 15 2000

UPPER LEVEL DISTURBANCE MOVING ACROSS THEN NORTHERN PLAINS IS STILL
A CONCERN FOR THIS EVENING. SATELLITE INDICATED SOME MID LEVEL
CLOUDINESS FROM BISMARCK TO MOBRIDGE MOVING EASTWARD. SOME CUMULUS
CLOUDS HAVE FORMED DURING THE PAST HOUR AT THE OFFICE. OTHERWISE ETA
MODEL IS THE MOST AGRESSIVE WITH PRINTING OUT PRECIPITATION AMOUNTS
THIS EVENING. THEREFORE...WILL CONTINUE A CHANCE OF SHOWERS IN THE
ABERDEEN GROUP AND A CHANCE OF SHOWERS AND THUNDERSTORMS IN THE
WATERTOWN GROUP FOR THIS EVENING. MODEL TIME CROSS SECTIONS
INDICATED A CLEARING SKY THIS EVENING ACROSS THE WEST AND CLEARING
AFTER MIDNIGHT ACROSS THE FAR EAST. FAN/FWC GUIDANCE WAS SEVERAL
DEGREES APART AND TOOK A COMPROMISE BETWEEN THE TWO.

ON TUESDAY...WEAK HIGH PRESSURE THEN BUILDS INTO THE UPPER MIDWEST.
HOWEVER CLOUDS WILL SPREAD NORTHEASTWARD INTO THE REGION DURING THE
DAY AS THE NEXT LOW PRESSURE SYSTEM DEVELOPS ACROSS THE CENTRAL
ROCKIES. FAN/FWC GUIDANCE GUIDANCE WAS SIMILIAR AND ON THE WARM SIDE
FOR HAVING AN EAST TO NORTHEAST FLOW. WITH CLOUDS SPREADING INTO THE
SOUTHWEST DURING THE MORNING AND ACROSS THE REST OF THE CWA DURING
THE AFTERNOON...WENT AT OR SLIGHTLY BELOW GUIDANCE VALUES FOR HIGHS.
WARMEST READINGS TOMORROW MAY BE IN THE FAR EAST WHERE MORE SUNSHINE
IS EXPECTED.

FOR TUESDAY NIGHT AND WEDNESDAY...THE UPPER LOW OVER THE DESERT
SOUTHWEST IS EXPECTED TO MOVE INTO THE CENTRAL PLAINS BY WEDNESDAY
EVENING. A SHORTWAVE AHEAD OF THE UPPER LOW WILL SWING INTO SOUTH
DAKOTA TUESDAY NIGHT AND WILL BRING ANOTHER CHANCE OF SHOWERS AND A
FEW THUNDERSTORMS. THEN THE SURFACE LOW PULLS OUT OF THE ROCKIES AND
THEN PUSHES EAST INTO NEBRASKA ON WEDNESDAY. A COOL...WET AND WINDY
DAY IS ON TAP...ESPECIALLY FOR CENTRAL AND SOUTHERN SOUTH DAKOTA.
FAN/FWC GUIDANCE LOOKS REASONABLY AND WILL FOLLOW.

...EXTENDED DISCUSSION...
EXTENDED MDLS (NOGAPS, MRF, CANADIAN) IN THE THU-SAT PERIOD DO HAVE
SOME SLIGHT DIFFERENCES BUT WERE NOT SIGNIFICANT. THEY ALL SHOW THE
BIG SFC LOW IN THE N KS/S NEB AREA AT 00Z THU MOVG E INTO THE C IA/N
MO AREA BY 12Z THU AND WEAKENING QUITE A BIT. THEREFORE...WILL
CONTINUE WITH A CHANCE OF RAIN ACROSS THE CWA THROUGH WED NIGHT.
THERE MAY BE SOME LEFT OVER RAIN IN THE ATY AREA THU MRNG BUT WILL
LEAVE OUT FOR NOW. OTHERWISE...FOR MUCH OF THU...THE MDLS SHOW HIGH
PRES BUILDING OVER THE AREA. THEREFORE...THU LOOKS TO BE DRY OVER
THE CWA. FOR THU NIGHT (00Z FRI) THROUGH FRI (00Z SAT)...THE MDLS
SHOW AN AREA OF SFC LOW PRES AND A WEAK COLD FRONT MOVG SE ACROSS
THE UPPER MIDWEST WITH THE CANADIAN MDL TRACKING THE SFC LOW FURTHER
N AND E OF THE NOGAPS AND MRF. THIS SFC LOW MAY SET OF SOME SHRAS
AND TSRAS ON FRI BUT THE CHC APPEARS TO BE SLIGHT. WILL CONTINUE
WITH DRY ON FRI AND SEE WHAT LATER MDL RUNS SHOW. HIGH PRES SHOULD
RULE THE WEATHER FRI NIGHT THROUGH SAT AS IT MOVES EAST OF THE CWA
BY SAT EVENING. THIS WILL ALLOW FOR WAA ACROSS C AND NC SD LATER
SATURDAY. FMR TEMPS DONT LOOK BAD.

.ABR...NONE.