099 
fxus65 kmso 080243 aab 
afdmso 


Area forecast discussion...updated 
National Weather Service Missoula Montana 
843 PM MDT Tuesday Oct 7 2008 


Update...cancelled wind advisories for western Montana and Lemhi 
County in Idaho. Decreased precipitation chances for the southern 
Clearwater Mountains in Idaho. 




&& 


Discussion...winds have decreased below advisory criteria this evening 
with sunset and a weakening surface pressure gradient. Still 
expect to see some winds continue across the northern rockies 
through the rest of the evening. Shower activity will continue 
through the night...with the best chance of precipitation 
remaining over the higher terrain. Rain showers will transition to 
snow showers overnight as the airmass continues to cool. No 
accumulation is expected however. Overnight temperatures will run 
cooler that last night...but expect winds and some cloud cover to 
keep temperatures warmer than the potential with clear and calm conditions. 




&& 


Aviation...winds will continue to decrease tonight as the surface 
pressure gradient weakens. Some rain showers are also moving across the 
area...periodically reducing visibilities...and obscuring the 
higher terrain. Shower activity will continue through the night 
with light snow showers possible overnight. 




&& 


Previous discussion... /issued 622 PM MDT Tuesday Oct 7 2008/ 


Update...added a Wind Advisory for Lemhi County in Idaho and 
extended the advisory for portions of western Montana until 9pm 
MDT. Increased wind speeds and wind gusts for this evening across 
all of western Montana and north central Idaho. 


Discussion...gusty westerly winds continue this evening behind 
the passage of a cold front earlier this evening. Because winds 
continue at or slightly above Wind Advisory criteria in many 
locations...decided to extend the advisory for portions of western 
Montana until 9pm this evening. Also added Lemhi County to the 
advisory as wind speeds have increased significantly over the last 
hour. Expect winds to gradually die out over the next several 
hours with sunset. Shower activity is expected to continue through 
the night as a series of weak disturbances ride through the flow 
aloft. Precipitation will likely switch from rain to snow showers 
overnight...but no accumulations are expected. 


Previous discussion... /issued 252 PM MDT Tuesday Oct 7 2008/ 


Winter like storm system to bring snow along the Continental 
Divide...southwest Montana and Lemhi County late Thursday night 
into this coming weekend... 


Discussion...tonight through Thursday...windy day today across 
parts of the northern rockies. Winds are expected to diminish in the 
valleys somewhat this evening with the setting sun....but with the jet 
stream still overhead...it should remain breezy near the mountains. 
Strong wind flow and cold air aloft are expected to keep scattered rain 
and snow showers going tonight with even some lower elevations 
seeing a bit of the white stuff. Brisk fall day on tap 
tomorrow...but it should be generally dry in the valleys. Then on 
Wednesday night...we should see our first widespread hard freeze 
of the season in a brief clearing period ahead of a developing 
storm that will be impacting the northern rockies Thursday and 
continue to affect the west into the weekend. 


Models in good agreement on developing cold low pressure system to 
impact the Continental Divide...southwest Montana and Lemhi County Idaho 
late Thursday night into this weekend. A trough of low pressure from 
the Gulf of Alaska will enter the inter-mountain west Thursday night 
with the focus of precipitation initially over Lemhi County and 
southwest Montana. Snow levels will lower to the valley floors 
overnight. Snow will then develop along the entire Continental Divide 
by late Friday as upslope northeast flow develops and lasts into 
the weekend. Accumulating snows are possible in these areas late 
Thursday through Saturday and begin to taper off Sunday as the low 
pressure system moves east of The Divide. Temperatures will be well 
below normal in this time frame. High pressure will begin to build 
over the area Monday. But models are inconsistent on solutions from 
Monday on. So confidence is low on how much warming and drying 
will occur next week. 


&& 


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


$$ 


Short term...via 
long term....sigler 
aviation...Foster