Severe Thunderstorm Warning 117, NWS Aberdeen, SD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
340 PM CDT TUE JUL 8 2003

.SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT.
FOCUS FOR THE SHORT TERM WILL BE CHANCE FOR THUNDERSTORMS ACROSS THE
CWA BEGINNING THIS EVENING THROUGH WED AFTERNOON. CURRENTLY HAVE AN
AREA OF THUNDERSHOWERS OVER THE EASTERN PORTION OF THE CWA...EXPECT
THESE TO CONTINUE EASTWARD AND BE OUT OF THE CWA BY EARLY EVENING.
THESE STORMS ARE JUST A LITTLE PRECURSOR TO THE MAIN EVENT EXPECTED
TO BEGIN LATE THIS EVENING. CURRENT SFC ANALYSIS SHOWING LOW
PRESSURE CENTERED OVER EASTERN WYOMING...WITH SOUTHEASTERLY FLOW OUT
AHEAD OF IT ACROSS THE MAJORITY OF SOUTH DAKOTA. THIS AREA OF LOW
PRESSURE IS ASSOCIATED WITH A STRONG S/WV CURRENTLY VISIBLE ON WATER
VAPOR IMAGERY OVER EASTERN MONTANA. AS THIS SYSTEM SLIDES EASTWARD
THROUGH THE NIGHT...THE ATMOSPHERE WILL BECOME INCREASINGLY UNSTABLE
ACROSS SOUTH DAKOTA. BY 06Z TONIGHT...A 60KT JET CORE BECOMES
ORIENTED OVER EASTERN SOUTH DAKOTA TO PROVIDE AN ADDED SOURCE OF
LIFT TO THE REGION. EXPECT THE BEST TIME FOR PRECIPITATION WILL BE
FROM AROUND 03Z TO 12Z WEDNESDAY AS THIS LOW SLIDES INTO CENTRAL
SOUTH DAKOTA. PWAT VALUES OFF THE 18Z ABR SOUNDING NOT AS IMPRESSIVE
AS EXPECTED...BUT STILL SUBSTANTIAL ENOUGH FOR ABUNDANT
PRECIPITATION. AS H85 FLOW PICKS UP TO AROUND 30KTS...EXPECT MORE
MOISTURE TO ADVECT INTO THE REGION THROUGHOUT TONIGHT ALSO. THE BEST
CHANCE FOR SEVERE STORMS LOOKS TO BE ACROSS OUR SW ZONES...WHERE THE
BEST INSTABILITY EXISTS. LATEST ETA RUN ALSO PLACES THE LARGEST
VALUES OF CAPE NEAR 1500J/KG AND LIS APPROACHING -7 IN THE AREA NEAR
PIR. WINDS SHEAR IS SIGNIFICANT ENOUGH FOR SUPERCELL DEVELOPMENT
WITH GOOD TURNING IN THE LOW LVLS...AND SOME SPEED SHEAR. WITH THE
SYSTEM STILL AFFECTING THE AREA THROUGH THE DAY WEDNESDAY HAVE KEPT
IN PRECIP MENTION ACROSS THE EAST THROUGH EARLY WED EVENING. HIGH
PRESSURE THEN BUILDS INTO THE NORTHERN PLAINS...AS THE UPPER RIDGE
OVER THE DESERT SW BEGINS TO TRANVERSE EAST. SHOULD SEE DRY
CONDITIONS THROUGH THE REMAINDER OF THE SHORT TERM...WITH PARTLY TO
MOSTLY SUNNY SKIES.

.LONG TERM...SATURDAY THROUGH TUESDAY
DID NOT MAKE A LOT OF CHANGES WITH THE EXTENDED PERIOD. GENERALLY
LOOKING AT THE SAME PATTERN OF A LARGE UPPER RIDGE OVER THE WESTERN
TWO THIRDS OF THE COUNTRY...AND A TROUGH OVER THE EAST. WILL SEE A
FEW SHORTWAVES RIDE OVER THE TOP OF THE RIDGE AND HELP TO SET OFF
PERIODS OF THUNDERSTORMS IN ASSOCIATION WITH A SLOW MOVING FRONTAL
BOUNDARY. THE BEST TIMES FOR STORMS LOOKS TO BE LATE SUNDAY NIGHT IN
THE WEST...MONDAY AFTERNOON AND EVENING...AND AGAIN DURING THE DAY
TUESDAY. CURRENT TEMPS LOOK GOOD...WITH H85 TEMPS GENERALLY IN THE
UPPER TEENS TO MID 20S THROUGHOUT THE PERIOD...WHICH SHOULD KEEP
TEMPERATURES RIGHT AROUND NORMAL.

.ABR...NONE.

ALBRECHT/PARKIN

MNZ039-046-SDZ003>011-015>023-033>037-045-048-051-091030-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE ABERDEEN SD
533 AM CDT TUE JUL 8 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PARTS OF CENTRAL...
NORTH CENTRAL AND NORTHEAST SOUTH DAKOTA...AS WELL AS
BIG STONE AND TRAVERSE COUNTIES IN MINNESOTA.

.DAY ONE...TODAY AND TONIGHT

A STATIONARY BOUNDARY OVER NEBRASKA WILL SLOWLY RETREAT TO THE
NORTH...APPROACHING THE PIERRE AREA TOWARD EVENING. AN UPPER LEVEL
LOW WILL MOVE THROUGH THE REGION ABOUT THE SAME TIME...SETTING THE
STAGE FOR THUNDERSTORM DEVELOPMENT...SOME OF WHICH MAY BECOME
SEVERE. THE PRIMARY AREA OF CONCERN WILL BE OVER COUNTIES ALONG THE
MISSOURI RIVER.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED LATER TODAY OR TONIGHT.

DORN