Weather

067 
fxus65 kmso 070953 
afdmso 


Area forecast discussion 
National Weather Service Missoula Montana 
353 am MDT sun Sep 7 2008 


Discussion...one final shortwave disturbance has begun to rotate 
through the northern rockies this morning as the region remains 
under northwest flow aloft. This will maintain one more day of 
cloudy and cool conditions with shower activity expected through 
the day. Main focus of precipitation will be along the Continental 
Divide and across southwest Montana with only isolated showers 
expected generally west of Missoula. As the disturbance begins to 
exit the region late this afternoon...a gradual clearing will 
occur. By early Monday morning...clear skies will dominate the 
entire region allowing for cooler low temperatures than have 
occurred over the past few nights. With lingering surface 
moisture...expect to see patchy fog form across the valleys of 
western Montana and north central Idaho. More widespread 
fog...locally dense...will be possible for locations near the 
Continental Divide. A slight warm up is in store for Monday with 
temperatures returning to near normal for this time of year. 


Tuesday through Wednesday...forecast models continue to dig a low 
pressure system out of southwest Canada Tuesday...then track it 
south across Idaho Tuesday night and Wednesday. This low system 
will offer clouds and increased chances of precipitation as 
moisture circulates back into most of western Montana and portions 
of north-central Idaho. Clouds and any precipitation will help Cool 
Valley maximum temperatures back into the upper 50s and 60s...while 
mountains may only see 40s and lower 50s on Wednesday. 


Thursday through Saturday...medium range models solutions begin 
to differ significantly with respect to the movement of the low 
system and its associated moisture. Poor consistency among the 
models diminishes overall forecast confidence. The GFS maintain a 
more northerly position...tracking the low across eastern Idaho 
and northwest Wyoming Thursday and Thursday night. At the same 
time...the Canadian and European model (ecmwf) models move the low center farther 
south over Utah. The GFS solution would continue to circulate 
moisture into Lemhi County and southwest Montana...while the other 
solutions would be drier and warmer. Will split the difference and 
trend probability of precipitation up and temperatures down across The Butte region and Lemhi 
County for Thursday. 


Models also having problems handling the next short-wave trough 
expected late Friday and Saturday. The GFS much stronger and 
faster with this feature than the European model (ecmwf)/Canadian models. 


&& 


Aviation...clouds and showers will be obscuring mountains across 
western Montana today...especially near the Continental Divide. In 
contrast...conditions will be improving across north-central 
Idaho today as drier air moves in from the west. Clouds are 
expected to decrease across western Montana tonight...however 
patchy valley fog is expected to develop early Monday morning. 


&& 


Mso watches/warnings/advisories... 
Montana...none. 
Idaho...none. 
&& 


$$ 


Short term...via 
long term....msj 
aviation...msj