Weather

360 
fxus63 kunr 051946 
afdunr 


Area forecast discussion for western South Dakota and northeastern Wyoming 
National Weather Service Rapid City South Dakota 
145 PM MST Monday Jan 5 2009 


Discussion...at 20z surface map shows Lee-side trough extending from 
eastern Montana south through eastern Wyoming/western South Dakota into western Nebraska/eastern Colorado. 
Weak short wave moving through central Montana producing clouds and some light 
snow across eastern Montana. Aloft...weak northwest flow continues to dominate weather. 


Tonight...weak short wave in central Montana will move east across the 
region. Not a lot of moisture with this system so expect only 
a low chance of snow across northestern Wyoming/northern blk hls and northwestern South Dakota. West-northwest 
upslope flow will bring best chances of precipitation to northern black hls 
..mainly from Terry Peak to O'Neil Pass. 


Tuesday...another weak short wave will moves across the region...again not 
much moisture to work with so will continue low chance probability of precipitation in northestern Wyoming/northern 
blk hls and northwestern South Dakota. Again...west-northwest upslope flow will bring best 
chances of snow to northern blk hls from Terry Peak to O'Neil Pass. 
Temperatures will be near seasonal norms...mainly in the 30s. 


Tuesday night through Wednesday...a series of weak S/w's will move through the 
northwest upper flow bringing a continued chance of snow. Moisture will 
increase late Tuesday night into Wednesday after...bringing a better chance 
of accumulating snow to northestern Wyoming/northern blk hls and northwestern South Dakota. A few 
inches of snow may fall in the northern Black Hills...mostly likely 
from Terry Peak to O'Neil Pass and over Butte and Harding 
counties in northwestern South Dakota. Seasonal temperatures can be expected to continue 
through the period. 


Extended...northwesterly flow aloft will dominate the weather 
late this week into the weekend. Arctic boundary will slide 
mostly east of the County Warning Area on Thursday...bringing warm temperatures to much 
of the area. An upper trough and cold front will then quickly mv 
across the region Thursday night and Friday...bringing a chance of 
snow...gusty winds...and cooler temperatures. At this time...temperatures are 
anticipated to be above average over the weekend with possibly 
another chance for precipitation toward the end of the weekend. 


&& 


Aviation...VFR conditions will continue across the area through 
tomorrow morning. With snow possible especially across the northern 
plains...some MVFR ceilings/visibility will be possible within the snowfall. 


&& 


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


&& 
$$