Damaging Wind in South Dakota, August 20, 2002

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
230 PM MDT TUE AUG 20 2002

A FEW STORMS OVR S CTRL COUNTIES ATTM IN AREA OF BEST INSTABILITY.
AREAS FURTHER W WL KEEP CLD CVR AND LIMIT HEATING REMAINDER OF THIS
AFTN...SO THINK BEST THREAT FOR SEVERE WX WL REMAIN IN S CTRL
COUNTIES WHERE WATCH IS IN EFFECT. A FEW TSMS OVR CTRL WY AS WELL
AND MAY MAKE IT INTO WRN COUNTIES THIS EVE SO INCLUDED 20 POPS
THERE.  EXPECT MORE CLD CVR ACRS AREA AND SOME LO CLDS BEING
INDICATED OVR N AFTER MIDNIGHT. EXPECT LOWS TO BE A GOOD 5 DEG ABV
MOS ACRS CWA. WINDS WL GRADUALLY SHIFT TO THE NE AS SFC LO MOVES
SLOWLY ACRS WRN SD.

WED...WINDS WL BE OUT OF THE NE ACRS CWA AND ALONG WITH MORE CLDS
SHLD KEEP TEMPS IN THE LWR TO MID 80S FOR HIGHS. ETA SHOWING VERY
STRONG AREA OF H25 DIVERGENCE MVG FM NW TO S CTRL SD DURING THE
AFTN. AVN SHOWING THIS A LTL AS WELL BUT DEFINITELY NOT AS STRONG.
WENT WITH 40 POPS ACRS MUCH OF WRN SD AND 30 POPS OVR NE WY AND SW
SD. WED NIGHT WL CONTINUE CHC FOR STORMS WITH S/W MVG THRU AND
BOUNDARY ACRS SRN SD COUNTIES INTO NE WY. LL WINDS WL BE E-NE AND
SHLD HELP SOME LO CLDS TO DVLP AND KEEP TEMPS ONCE AGAIN AROUND 60
FOR LOWS.

THU...ANOTHER S/W WL MOVE ACRS CWA AS SW FLOW ALF CONTINUES ACRS
AREA. DECENT AREA OF LIFT ASSOCIATED WITH THIS WAVE AND THERE WL BE
PLENTY OF MOISTURE AROUND WITH THE SE FLOW. ETA SHOWING CAPES
NEARING 2000 J/KG BY THE AFTERNOON. DECENT SHEAR ALSO FCST SO THREAT
FOR SVR WX LKS GD. ANOTHER S/W WL EJECT OUT OF GREAT BASIN FOR
FRI...BUT SOME DISAGREEMENT ON ITS STRENGTH LKG AT 60 HR ETA AND
AVN...AND WITH SOME DRIER AIR MVG IN THU NIGHT...JUST WENT WITH 20
POPS ACRS WRN CWA.

FOR SAT AND SUN...AVN TRYING TO PUT OUT SOME LT PRECIP BUT WITH WEAK
FLOW AND RDG OVR AREA THINK WE WILL GENERALLY STAY DRY. BY MON AND
TUE...UP LO APPROACHES AREA AND BRINGS BACK ANOTHER CHC FOR STORMS.
THINK TEMPS MAY BE A LTL WARMER THAN WHAT AVN IS SHOWING GIVEN THE
SW FLOW AHEAD OF TROF...SO WARMED TEMPS UP INTO THE 80S THRU MON AND
A BIT COOLER TUE AS LO MOVES OVR ROCKIES.

.UNR...RED FLAG WARNING FOR DRY LIGHTNING FOR FIRE ZONES 297N 297S
298 AND 299...WHICH ARE THE PLAINS OF NORTHEAST WYOMING AND THE
WYOMING BLACK HILLS.
       FIRE WEATHER WATCH FOR DRY LIGHTNING FOR FIRE ZONES 260 AND
262 WHICH IS THE SOUTH DAKOTA BLACK HILLS.
       SEVERE THUNDERSTORM WATCH FOR SOUTH CENTRAL SOUTH DAKOTA
UNTIL 7 PM MDT.

JMG