Severe Thunderstorm Warning 124, 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 WED JUL 18 2001

INTERESTING DAY. VERY UNSTABLE AIR IN PLACE OVER THE AREA.  MORNING
SOUNDING SHOWED 5500 J/KG CAPE AND LI OF -12.5C WITH A PRECIPITABLE
WATER OF 1.42.  NOT BAD FOR A MORNING SOUNDING.  LAST EVENINGS
SOUNDING SHOWED CAPES OF 7800 AND -16.  VERY INTERESTING VALUES FOR
THIS PART OF THE COUNTRY.  AFTERNOON HEATING CONTINUES TO DESTABILZE
AIR UNDER FAIRLY STRONG CAP.  LATEST GOES DERIVED PRODUCTS FROM 16Z
CONFIRM VERY HIGH CAPE VALUES AND DECREASING CINH VALUES UNDER 100
J/KG JUST WEST OF ABERDEEN.  STILL HAVE VERY WARM MID LAYER IN PLACE
WITH H7 TEMPERATURE OF +11 ON 12Z SOUNDING AND +12 ON GOES DERIVED
SOUNDING.  THIS WARM MID LAYER WOULD NORMALLY BE ENOUGH TO INHIBIT
CONVECTION IN THIS AREA.  HOWEVER AGREE WITH SPC ON EXISTENCE OF SUB
SYNOPTIC BOUNDARIES CLOSE TO THIS AREA TO FOCUS CONVERGENCE AS WELL
AS SYNOPTIC BOUNDARIES TO THE NORTH AND WEST.  H5 WAVE IS MOVING
OVER EAST CENTRAL PART OF THE STATE THAT WILL ALSO AID DEVELOPMENT.
WITH CAP ERODING WILL MENTION CHANCE OF THUNDERSTORMS...SOME
POSSIBLY SEVERE...IN THE EASTERN HALF OF THE AREA.  EXPECT THE MOST
LIKELY AREA TO BE THE NORTH AND EAST PART OF AREA.  NEXT SIGNIFICANT
CHANCE WILL OCCUR THURSDAY NIGHT AND FRIDAY AS STRENGTHENING H5 WAVE
CLOSES OFF OVER NORTHEAST SOUTH DAKOTA.

.EXTENDED DISCUSSION...
EXTENDED MODELS CONTINUE TO SHOW NO RELIEF IN THE HEAT OR HUMIDITY
THROUGH MUCH OF THE EXTENDED PERIOD AS 500MB RIDGE MOVES LITTLE
THROUGH PERIOD. THEREFORE...BIGGEST ISSUE WILL BE THE CHANCES FOR
CONVECTION. THINK MOST OF THE CONVECTION SATURDAY AND SUNDAY WILL
STAY NORTH OF THE AREA AS AVN MODEL WOULD SUGGEST THAT WE WOULD BE
CAPPED. WEAK FRONTAL BOUNDARY PUSHES THROUGH THE REGION ON MONDAY
WHICH WILL GIVE MUCH OF THE CWA A CHANCE FOR STORMS...THEN HIGH
PRESSURE MOVES IN ON TUESDAY. THE HIGH THEN PUSHES OFF TO THE EAST
ON WEDNESDAY AS MRF DEPICTS ANOTHER LEESIDE TROUGH PUSHING INTO THE
WESTERN PLAINS DURING THE DAY. WITH LITTLE CHANGE IN THE RIDGE
PATTERN ALOFT...WENT SIGNIFICANTLY WARMER THAN MRF/MEX GUIDANCE FOR
HIGHS EACH DAY. LOWS SEEMED A TAD LOW IN THE LATER PERIODS...
THEREFORE WENT AT OR SLIGHTLY ABOVE GUIDANCE VALUES DURING THE
PERIOD.

.ABR...NONE.

KEEFE/ECKBERG

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ABERDEEN, SD
942 PM CDT WED JUL 18 2001

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

0834 PM    5 NE EUREKA               SD   TORNADO
07/18/01   MCPHERSON                      REPORTED BY
SPOTTERS

0837 PM    5 E HOVEN                 SD   TORNADO
07/18/01   POTTER

SDZ006-007-011-018>020-022-200530-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE ABERDEEN SD
1201 AM CDT THU JUL 19 2001

...TORNADO WATCH HAS EXPIRED...

THE TORNADO WATCH WHICH WAS IN EFFECT FOR MUCH OF NORTHEAST SOUTH
DAKOTA HAS BEEN ALLOWED TO EXPIRE.

MOHR

SDZ003-004-009-015-016-033>037-190815-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE ABERDEEN SD
300 AM CDT THU JUL 19 2001

...SEVERE THUNDERSTORM WATCH NUMBER 584 ALLOWED TO EXPIRE...

THUNDERSTORMS HAVE MOVED EAST INTO NORTHEAST SOUTH DAKOTA. THESE
THUNDERSTORMS WILL CONTINUE TO MOVE EAST AND NO REDEVELOPMENT IS
EXPECTED TO THE WEST.  THEREFORE...SEVERE THUNDERSTORM WATCH NUMBER
584 HAS BEEN ALLOWED TO EXPIRE FOR THE FOLLOWING COUNTIES IN SOUTH
DAKOTA: CAMPBELL...CORSON...DEWEY...HAND...HUGHES...HYDE...POTTER...
STANLEY...SULLY AND WALWORTH.

FAUCETTE