Severe Thunderstorm Warning 53, NWS Aberdeen, SD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
225 PM CDT SAT JUN 21 2003

.SHORT TERM...TONIGHT THROUGH MONDAY
18Z ABR SOUNDING SHOWS CLASSIC HIGH-BASE PROFILE FOR A DRY
MICROBURST...SEVERE OUTFLOW WINDS AND LARGE HAIL.  CAPE HAS
INCREASED TO HALF THAT OF THE TO FIRE CONVECTION...SURFACE TEMP IS
NEAR 80 AND HAVE SEEN 80 AT TIMES TODAY.  DEWPOINTS HAVE INCREASED
TO THE 60 ACROSS MUCH OF EAST AND NORTHEAST SOUTH DAKOTA.  LIS
DECREASING EACH HOUR ACCORDING TO LAPS.  ATMOSPHERE IS STEADILY
DESTABILIZING.

VISIBLE SATELLITE IMAGERY SHOWS OUTFLOW BOUNDARIES BEGINNING TO
COLLIDE WITH DRY LINE AND COLD FRONT WITH RESULTANT CONVECTION.  SPC
WATCH BOX OVER WESTERN ZONES WELL IN LINE WITH CONDITIONS.  EXPECT
CONVECTION TO SPREAD EAST WITH TIME THOUGH MAY DECREASE IN INTENSITY
WITH TIME.

MODELS SHOW SUNDAY EVEN MORE UNSTABLE.  EXPECT ADDITIONAL CONVECTIVE
EPISODES WITH POSSIBLE SEVERE CONDITIONS AS THE COLD FRONT LINGERS
OVER THE CWA.  BAROCLINIC ZONE SHOULD WEAKEN AND EXIT THE REGION BY
LATE SUNDAY EVENING.  POST FRONTAL INSTABILITY COMBINED WITH LOCAL
MOISTURE AND INSTABILITIES COULD FIRE PULSE TYPE CONVECTION
MONDAY... PARTICULARLY IN THE EASTERN ZONES.  MCNULTY

.LONG TERM...MONDAY NIGHT THROUGH SATURDAY.
SIGNIFICANT SHEAR AND LOW LEVEL MOISTURE PROFILE IS MAINTAINED
MONDAY NIGHT AND TUESDAY WITHIN BOTH THE GFS AND ETA...EVEN THOUGH
SFC FRONT WILL BE MOSTLY THROUGH CWA. THIS FRONT WILL BE NEARLY
STATIONARY THROUGH THIS PORTION OF THE DAYS 2 AND 3...SO THE
PROLONGED EXPOSURE TO LOW LEVEL MOISTURE SEEMS CREDIBLE. S/WS TO
CONTINUE THEIR PROGRESSION THROUGH CWA IN WSW FLOW DURING THAT
TIMEFRAME...AND EXPECT THERE WILL BE A DECENT SHOT AT PRECIP EACH
PERIOD FROM MONDAY NIGHT INTO BEGINNING OF EXTENDED.

UNBEARABLE 00Z OPERATIONAL GFS HAS EVOLVED CONSIDERABLY IN THE 12Z
CYCLE AND IS NOW FALLING IN LINE MUCH BETTER WITH ECMWF AND
GFS/ECMWF ENSEMBLES. GFS NOW SLOWS UPPER LEVEL TROUGH PASSAGE DOWN
AND BRINGS IT THROUGH CWA LATE WEDNESDAY. ETA AND ECMWF CONTINUING
TO TREND THIS WAY. IN ALL LIKELIHOOD...SFC FRONT WILL BE SOUTH AND
EAST OF CWA BY WEDNESDAY MORNING...BUT WITH UPPER LEVEL DYNAMICS
ABOUNDING AND PLETHORA OF JET MAXIMA TO WORK WITH...FEEL THAT
KEEPING SMALL CHANCE POPS FOR WEDNESDAY IS WORTHWHILE.
OTHERWISE...EXTENDED CONSISTS OF SFC RIDGING AND DRYING. BY DAY
7...UPPER LEVEL PATTERN TAKES ON RIDGE IN THE WEST/TROUGH IN THE
EAST CONFIGURATION. KEPT MAX/MIN T GRIDS DAYS 4 THROUGH 7 AOA MEX
ENSEMBLE MEANS FOR THE MOST PART.  DORN

.ABR...NONE.

MNZ039-046-SDZ003>011-015>023-033>037-045-048-051-221000-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE ABERDEEN SD
507 AM CDT SAT JUN 21 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

SHOWERS AND THUNDERSTORMS WILL SPREAD ACROSS THE AREA THIS AFTERNOON
AND EVENING. SOME OF THE STORMS MAY BE SEVERE.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH THE DAY SUNDAY AND
OVERNIGHT INTO EARLY MONDAY MORNING. SOME OF THE STORMS MAY BE
SEVERE.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED LATER TODAY OR TONIGHT THROUGH
SUNDAY NIGHT.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ABERDEEN, SD
612 PM CDT SAT JUN 21 2003

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

0542 PM    20 N TIMBER LAKE          SD   1.00 INCH HAIL
06/21/03   CORSON

NDM

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ABERDEEN, SD
743 PM CDT SAT JUN 21 2003

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

0735 PM    SENECA                    SD   .75 INCH HAIL
06/21/03   FAULK

NDM