979 
fxus65 ktfx 071148 aaa 
afdtfx 


Area forecast discussion...updated 
National Weather Service Great Falls Montana 
548 am MDT sun Sep 7 2008 


Updated aviation section 


Discussion... 
today through Tuesday...there will be a change in the weather 
pattern during the period. The cool moist northwest flow aloft of 
late will transition to a warmer and drier westerly flow aloft by 
Tuesday. For today another weather disturbance will be affecting 
the area. Although models do not indicate much if any lift with 
the disturbance there will certainly be moisture and instability. 
Will go with a scattered shower forecast. However over the east 
slopes of the Rocky Mountains there will be the additional factor 
of low level upslope flow so will continue the idea of higher than 
scattered probability of precipitation there. Again today it appears there will be enough 
instability for isolated thunderstorms. For tonight a much drier 
airmass is forecast to move into the area ahead of a weak ridge of 
high pressure aloft. With clearing skies expected and light winds 
and recent precipitation would not be surprised to see a few 
areas of fog late tonight/early Monday morning. No area really 
stands out as being likely to see fog but could possibly see some 
over central Montana. On Monday the weak upper ridge will move 
over the forecast area for a dry day and should see a fair amount 
of sunshine...particularly in the south. On Tuesday a rather strong 
upper trough will be moving southeast through British Columbia and 
expect to see an increase in high level moisture. Could see weak 
instability over the far west zones. Although do not see much lift 
can not rule out isolated showers or thunderstorms. Temperatures 
will warm Monday and Tuesday with highs by Tuesday near or 
possibly a little above normals for this time of the year. Blank 


Tuesday night through Friday night...a return to northwesterly flow 
aloft is anticipated for the region during the extended forecast 
period. A weak storm system that had been previously forecast in 
the region during Wednesday...is now depicted to move more slowly 
and farther south prior to reaching the forecast area. As of right 
now...this storm system is forecast to affect the region Wednesday 
through Thursday night. Guidance had been depicting the entire upper 
level hemispheric pattern transitioning from practically 
stationary to more progressive by Wednesday...however it appears 
that most of the longwave features present at forecast issuance 
this morning persist across North America through day 7. Bottom 
line...limited confidence exists for Wednesday and Thursday 
precipitation and temperature forecasts due to recent model 
performance. Due to the persistent northwesterly 
flow...temperatures are anticipated to remain at or below the 
seasonal average during the entire extended forecast period. 
Zumpfe 


Saturday and Sunday...models continue to depict a northwest flow 
aloft over Montana through the weekend. A disturbance may pass 
through the flow Saturday so increased precipitation chances for the 
north Central Plains. Temperatures are expected to be slightly below 
seasonal averages. Jns 




&& 


Aviation... 
updated 1148z. 
A weak upper level storm system will affect routes and terminals 
during the next 24 hours. VFR flight conditions are anticipated to 
prevail during this time...however occasional MVFR ceilings may 
exist due to shower activity through 03z...particularly near khln and 
kbzn. Widespread terrain obscurations will also be present through 06z. 
Surface winds will be quite weak and variable across the region 
during the forecast period as well. Zumpfe 


&& 


Preliminary point temps/pops... 
gtf 55 36 68 42 / 60 20 0 0 
ctb 53 38 66 38 / 60 20 10 10 
hln 58 42 72 42 / 50 20 0 0 
bzn 60 36 73 38 / 60 20 0 0 
wey 56 30 68 33 / 30 10 0 0 
dln 63 35 72 40 / 30 10 0 0 
hvr 59 37 67 38 / 30 20 0 10 
lwt 51 33 64 38 / 60 30 0 0 


&& 


Tfx watches/warnings/advisories... 
none. 
&& 


$$ 


Short term...blank 
long term...zumpfe/Saucier 
aviation...zumpfe 


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