Weather

729 
fxus63 kunr 070915 
afdunr 


Area forecast discussion for western South Dakota and northeastern Wyoming 
National Weather Service Rapid City South Dakota 
303 am MDT sun Sep 7 2008 


Discussion...current water vapor imagery shows shortwave moving 
into southeastern Montana. Showers are developing across southeast 
Montana and northeastern Wyoming as the shortwave moves into the 
County Warning Area. Expect showers to increase in coverage as they progress 
eastward later this morning. With precipitation around again 
today...high temperatures will be on the cool side with highs only 
climbing into the 50s to lower 60s at most locations. Higher 
elevations in the Black Hills will only see highs in the 40s. 
Secondary shortwave will move into the County Warning Area this evening. Both the 
NAM and GFS continue to indicate a broad area of precipitation along the 
South Dakota and Nebraska border. This precipitation is expected to 
develop late in the afternoon and continue into this evening. 
Shortwave will move east of the area Monday afternoon bringing an 
end to the precipitation. Low temperatures will be very cool 
Sunday night with many locations dipping into the middle 30s. Zonal 
flow will set up across the area on Tuesday as a weak surface high 
settles over the region. Return flow will set up across the area 
Tuesday afternoon as the surface high slides east of the area and 
low pressure develops over western Montana. Surface low is expected to 
move toward northwest South Dakota late Tuesday night as upper 
trough digs into the central rockies. 


Extended...some unsettled weather is expected to return for the 
second half of the work week. Weak cyclonic flow aloft will move in 
from the west. Latest GFS shows the base of the trough cutting off 
across the northern rockies midweek...and drifting eastward as it 
phases back into the main flow Thursday into Friday. Have added 
slight chance probability of precipitation to the western half of the County Warning Area Thursday for 
now...however confidence in this solution...or any solution is low 
given how poorly models handle upper lows this far out. 


&& 


Aviation...some areas will see patchy fog this morning. Scattered 
-shra are expected again today and tonight. The strongest showers 
will reduce conditions to MVFR at times. 


&& 


Unr watches/warnings/advisories... 
South Dakota...none. 
Wyoming...none. 
&& 


$$