359 
FXUS63 KUNR 290824
AFDRAP

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
230 AM MDT THU JUL 29 1999

THE 08Z SURFACE ANALYSIS HAD TROUGH FROM MN TO SOUTHWEST SD AND 
ANOTHER OVER EASTERN MT/WY. WATER VAPOUR LOOP REVEALED TROPICAL WAVE 
OVER THE NE PANHANDLE AS THE IR MOVIE SHOWED DISSIPATION OF COOLER 
TOPS. LATEST KLBF/KUDX WSR-88D/S CONFIRM DEMISE OF STRONGER 
CONVECTION. UPPER RIDGE WILL PERSIST OVER AREA TODAY WITH CHANGES ON 
TAP FOR THE WEEKEND COURTESY OF SHORTWAVE MOVING THROUGH WESTERN 
CANADA. CONCERNS INCLUDE POPS AND TEMPERATURES.

THE 00Z ETA/NGM/AVN INITIALIZED ALRIGHT AND AT 06Z REPRESENTED 
REALITY. UPPER RIDGE REMAINS OVER AREA TODAY AS WEAK SPOT OVER NE 
DRIFTS EAST-NORTHEAST. THIS WAVE AS WELL AS FORCING ALONG SD/MN 
SURFACE TROUGH WILL CAUSE SCATTERED TSRA THIS AFTERNOON AND EVENING. 
UPPER AIR TEMPERATURES SIMILAR TO YESTERDAY...SO SIMILAR HIGHS 
EXPECTED. EXCEPTION WILL BE BEHIND SURFACE TROUGH WHERE WINDS WILL 
SHIFT TO THE EAST/NORTHEAST THIS AFTERNOON. THE LARGEST EFFECT WILL 
BE FELT IN THE CENTRAL/NORTHERN FOOTHILLS AND BLACK HILLS AS 
EASTERLY UPSLOPE TAKES HOLD. THIS MAY ENHANCE CONVECTIVE POTENTIAL.

TONIGHT/FRIDAY...SHORTWAVE ENERGY WILL ZIP ACROSS SOUTHERN CANADA 
WITH MODEST QG/FRONTOGENETIC FORCING INTO THE NORTHERN PLAINS. 
SLIGHTLY COOLER MID-LEVEL TEMPERATURES AND LINGERING SURFACE TROUGH 
WILL SUPPORT CHANCE POPS AND LOWER TEMPERATURES.

IN THE EXTENDED...THERE IS SOME QUESTION AS TO HOW MUCH COOL AIR 
WILL ACTUALLY PENETRATE HOT DOME OVER AREA FOR THE WEEKEND. HOWEVER 
FOR RIGHT NOW...SEE NO GOOD REASON TO KEEP TREND OF TEMPERATURES 
MOVING INTO THE 80S WITH A DAY-TO-DAY CHANCE OF STORMS.

COORDINATED WITH KABR/KBIL.

UNR...NONE.

HELGESON