Severe Thunderstorm Warning 108, NWS Aberdeen, SD

AREA FORECAST DISCUSSION FOR CENTRAL/NORTHCENTRAL AND NORTHEAST
SOUTH DAKOTA AND WEST CENTRAL MINNESOTA
NATIONAL WEATHER SERVICE ABERDEEN SD
315 PM CDT SUN JUL 15 2001

DECENT SHORTWAVE ON VISIBLE/INFRARED SATELLITE MOVING ACROSS WYOMING
INTO SOUTHERN MONTANA THIS AFTERNOON...WITH THE TAIL OF THIS SYSTEM
EXTENDING SOUTHWARD INTO NORTHEAST COLORADO.  THIS WILL BE THE MAIN
WEATHER FEATURE TONIGHT AS MODELS ARE PROGGING THIS FEATURE AND
SURFACE BOUNDARY DRAPED ACROSS THE WESTERN HIGH PLAINS TO MOVE INTO
CENTRAL SOUTH DAKOTA OVERNIGHT. THERE IS A SLIGHT RISK OF SEVERE
THUNDERSTORMS OVER MUCH OF THE WESTERN TWO-THIRDS OF THE CWA WITH
MAIN THREAT DAMAGING WINDS AND LARGE HAIL. HOWEVER...VERY HEAVY RAIN
IS EVEN A BIGGER CONCERN AS PRECIPITABLE WATER VALUES ARE AROUND
1.5 INCHES PER 12Z ETA TO NEAR 2.0 INCHES AROUND MOBRIDGE ON THE
GOES SOUNDER. THIS IS ABOUT 150-175 PERCENT OF NORMAL. ALSO...USING
MBE VELOCITY FORECAST ON BUFKIT WOULD INDICATE STORM MOTION SHOULD
BE 15 KNOTS OR LESS THROUGH MUCH OF THE OVERNIGHT PERIOD. WITH THIS
IN MIND...THOUGHT ABOUT A FLASH FLOOD WATCH OVER NORTH CENTRAL SOUTH
DAKOTA WHERE A LINE OF STORMS WERE FORMING WITH TRAINING CELLS ALONG
THIS LINE. AFTER COORDINATING WITH KBIS AND KRAP...WILL NOT GO WITH
A FLASH FLOOD WATCH...BUT WILL WORD ZONES HEAVY RAIN POSSIBLE. LOWS
TONIGHT SHOULD DROP INTO THE MID 60S TO NEAR 70 IN MOST LOCATIONS.

ON MONDAY...UPPER LEVEL SYSTEM SLOWLY PUSHES AWAY FROM THE REGION
DURING THE DAY...WITH MODELS CONTINUING TO DEPICT SHOWER AND
THUNDERSTORM ACTIVITY ACROSS THE EAST. FRONTAL BOUNDARY REMAINS
DRAPED ACROSS THE EASTERN PORTIONS OF THE CWA. WILL LEAVE A 30 POP
IN FOR THE MORNING IN THE ABERDEEN GROUP PER 12Z ETA TIME CROSS
SECTION AND WILL JUST MENTION A 40 POP IN THE WATERTOWN GROUP. DID
NOT MENTION TIMING IN THIS GROUP BECAUSE THERE WILL BE SOME ACTIVITY
DURING THE EARLY MORNING AND THEN AGAIN DURING THE LATE AFTERNOON AS
FRONTAL BOUNDARY WILL BE THE FOCUSING MECHANISM. ANOTHER UPPER LEVEL
DISTURBANCES PASSES OVER THE REGION MONDAY NIGHT...THEREFORE
MENTIONED A SMALL POP IN THE ABERDEEN AND WATERTOWN GROUPS WHEN THIS
UPPER LEVEL FEATURE INTERACTS WITH THE SURFACE BOUNDARY. TOOK A
BLEND OF FWC/MAV GUIDANCE AS CLOUD COVER COULD HINDER TEMPERATURES
FROM REACHING THE HIGHER MAV GUIDANCE TEMPERATURES OVER THE EAST.
WENT A TAD ABOVE GUIDANCE FOR LOWS MONDAY NIGHT.

FOR TUESDAY AND TUESDAY NIGHT...ETA/AVN SURFACE FEATURES DIFFER
SOMEWHAT WHICH WILL MAKE FOR AN INTERESTING FORECAST. WILL TREND
TOWARD THE AVN SURFACE SOLUTION WHICH WOULD PUT THE EASTERN PORTIONS
OF THE CWA IN THE WARM SECTOR WITH A CLOSED SURFACE LOW TO THE WEST
OF ABERDEEN. ETA SURFACE PATTERN DEPICTS A WARM FRONT DRAPED ACROSS
THE NORTHERN CWA DURING TUESDAY AFTERNOON WITH NO CLOSED LOW. WILL
GO TOWARD THE WARMER GUIDANCE FOR HIGHS ON TUESDAY AND WILL INCLUDE
A 20 TO 30 POPS IN THE EAST TUESDAY AFTERNOON AND TUESDAY NIGHT.

.EXTENDED DISCUSSION...
WEATHER PICTURE STILL REMAINS RATHER MUDDLED HEADING INTO NEXT
WEEKEND. FOR WED...5H RIDGE REBOUNDS AFTER WAVE PASSAGE THIS
WEEKEND...WITH 5H AND 7H HGTS AND TEMPS WARMING. SFC LOW TAKES SHAPE
WRN SD/ERN WY AREA WITH WARM FRONT WELL NORTH OF CWA. THE CANADIAN
MODEL IS SIMILAR IN KEEPING THINGS DRY..BUT HAS FRONT SOUTH OF CWA
AND COOLER HIGH PRESS IN CONTROL. 12Z AVN/MRF/AND ECMWF ALL AGREE IN
KEEPING CWA IN WARM SECTOR WITH GOOD SOUTHERLY FLOW AHEAD OF
DEVELOPING LOW. ON THURSDAY...LOW ELONGATES OR OPENS INTO A
TROF...DEPENDING ON WHICH MODEL YOU LOOK AT...AND MOVES EAST.
MRF/AVN AND CANADIAN SHOW 5H VORT MAX SLIDING INTO SRN CWA BY 00Z
FRIDAY. AVN 7H OMEGA FIELDS AS WELL AS RH PROGS SHOW MCS DEVELOPMENT
ACROSS FAR NERN COUNTIES...BUT 7H TEMPS FIELD STILL WARM ENOUGH FOR
CAP...MAYBE. MORE STRATIFORM TYPE PCPN LOOKS TO TAKE PLACE FURTHER
SOUTHWEST IN KPIR AREA. FOR FRIDAY...FRONT CONTS TO SAG SOUTH OF CWA
WITH HIGH PRESSURE BUILDING IN. ECMWF DEVELOPS SFC LOW SRN END OF
FRONT AND KEEPS FRONT ORIENTED W-E ACROSS CENTRAL SD. WITH WEST
COAST 5H LOW BEGINNING TO EJECT AND MOVE OVER TOP OF RIDGE...
FLATTENING IT AS IT GOES...AM MORE INCLINED TO BELIEVE THE FURTHER
SOUTH SOLN OF THE MRF. FRONT APPEARS TO STALL SOUTH OF CWA WITH
OVERRUNNING SITN SETTING UP INTO SATURDAY. SFC LOW REMAINS WELL
SOUTH OF CWA...AND THINK THAT MRF QPF BIT OVERDONE FOR MOST OF CWA.
ON SUNDAY...5H RIDGE BEGINS TO REBOUND WITH CWA IN NW FLOW. LAYERS
DRY NICELY WITH SFC HIGH CONT TO PUSH IN. MRF SHOWS WEAK 7H VORT
LOBE CLIPPING NERN COUNTIES AND CONTS TO SHOW ABUNDANT OVERRUNNING
PCPN FOR CWA. THINK THAT THIS MAY BE OVERD
ONE. FMR/MEX TEMPS SEEM
REASONABLE.

.ABR...NONE

ECKBERG/HINTZ

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ABERDEEN, SD
435 PM CDT SUN JUL 15 2001

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

0N725 PM    3 N CRESBARD              SD   WIND DAMAGE
07/14/01   FAULK                          60-65 MPH WIND WITH
                                          TREES DOWN                                        DOWN.

MF