573 
fxus65 kmso 180329 
afdmso 


Area forecast discussion 
National Weather Service Missoula Montana 
929 PM MDT Wednesday Mar 17 2010 


Update...decreased probability of precipitation and adjusted sky cover tonight into 
Thursday morning. 




&& 


Discussion...upper level energy is mainly confined to northwest 
Montana and along The Divide this evening...with mainly clear 
skies across the south. Looks like with the upper flow becoming 
more northerly overnight into Wednesday...the precipitation will 
remain confined to the Continental Divide through Thursday 
morning. Therefore adjusted the probability of precipitation tonight through early 
Wednesday to account for this. Temperatures will be much cooler in 
the higher terrain...but close to this mornings readings in most 
of the western Montana/west central Idaho valleys. Current 
forecast had this trend well in hand. 




&& 


Aviation...light winds and partly cloudy skies will remain across the 
northern rockies overnight. Upper level clouds will start to 
increase as the next weather system approaches from the north... 
also tightening the surface pressure. Winds will shift to the 
north-northeast at the airfields...with the strongest winds 
expected along the Continental Divide and south of the I-90 
corridor midday Thursday. Some light and mostly terrain locked 
showers will accompany this system...but showers are not expected 
to impact ceilings or visibilities at the terminals. Winds will 
decrease early Thursday evening...with some middle level clouds 
lingering over the area. 








&& 


Previous discussion... /issued 234 PM MDT Wednesday Mar 17 2010/ 


.Scattered snow showers late tonight through Thursday night... 


Discussion...as advertised all week a ridge of high pressure will 
amplify along the West Coast of the U.S. And Canada which will 
produce a northerly flow into the northern rockies. A couple of 
upper level disturbances will move through this flow and produce 
scattered snow showers across much of western Montana...especially 
along the Continental Divide. Temperatures will be slightly below 
normal during this period. 


Friday afternoon the weather disturbances will have moved 
southeast of the region. This drier and colder air will produce 
cold temperatures...especially in southwest Montana and the 
valleys near The Divide on Friday night. Single digit readings in 
Butte are not out of the question at this time. 


Saturday and Sunday. High pressure is expected to return to 
north central and western Montana Saturday and persist into Sunday. 


Sunday night into Tuesday. The 12z medium range operational 
GFS/European model (ecmwf) as well as the GFS ensembles indicate the next weather 
system and surge of moisture should shift eastward over Idaho and 
western Monday Sunday night and Monday. A fairly cool trough of 
low pressure...but more of a split flow pattern...may develop by 
Tuesday. 


&& 


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


$$ 


Update...Mead 
previous discussion...rpn/bauck 
aviation...Nolte