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Area forecast discussion 
National Weather Service Great Falls Montana 
1040 PM MDT Wednesday Aug 27 2008 


Updated aviation section 


Update... 
will update zone and state forecasts by 930 PM MDT. Winds at 
various observation points along the Rocky Mountain front and in 
Glacier County have generally decreased this evening and mostly 
fallen/remained below high wind criteria. Despite not seeing an 
observation from Logan Pass for quite some time (where winds have 
been strongest)...the overall trend seems to indicate that 
extending the High Wind Warning is not warranted. Therefore...have 
allowed it to expire at 9 PM MDT. However...winds remain fairly 
strong out towards hill and Blaine counties as the upper trough 
continues to exit the area. Therefore...will increase winds there 
for the remainder of the evening. Also...isolated showers will 
continue to move through that area this evening...but conditions 
up stream from the showers indicate that they should not last too 
long after midnight. Isolated...but decreasing...lightning 
strikes indicate that there will also be a slight chance of 
thunderstorms. Temperatures are generally in good shape. Coulston 


&& 


Aviation... 
updated 0440z. 
Expect VFR conditions. Winds have diminished. Thursday expect winds 
to increase again during the late morning and early afternoon. Feel 
confident on a westerly wind direction with these winds but guidance 
differs on how strong the winds will be so confidence in wind speeds 
is rather low. Tended to go with the guidance with the stronger 
winds during the afternoon and tended to split the difference 
between the stronger and weaker guidance during the evening. As for 
clouds...expect areas of ceilings above 20000ft. Blank 


&& 


Previous discussion... 
/issued 533 PM MDT Wednesday Aug 27 2008/ 


Tonight through Friday...upper level shortwave energy continues to 
move through the region tonight and will move east of my forecast 
area by midnight. Behind the trough weak shortwave ridging will 
build over the area for drier and warmer conditions over the next 
few days. Strong winds continue to impact the higher elevations of 
Glacier park and southward along the Continental Divide...although 
the lower elevations have not experienced widespread strong 
winds. Winds should diminish across the region after 9 PM MDT but 
will remain breezy for the next 30 hours or so. By Friday...expect 
the entire region to be back to Summer-like conditions with much 
warmer temperatures and generally light winds. Mpj 


Friday night through Monday night...the large scale upper level 
pattern appears quite progressive during the extended forecast 
period. An upper level ridge of high pressure is anticipated to 
transition to southwesterly flow aloft between Friday night and 
Saturday afternoon. Afternoon temperatures are expected to be above 
the seasonal average on Saturday...with surface winds increasing 
from the west and southwest ahead of the next Pacific storm system. 
A surface cold front will likely move through the forecast area 
between Saturday evening and Sunday afternoon. Temperatures will 
cool as much as 20 degrees from Saturday afternoon to Sunday 
afternoon. Guidance depicts relatively stronger precipitation 
producing features during the Saturday night through Monday morning 
period compared to those depicted yesterday. Precipitation chances 
are maximized during Sunday night...as the cold core of air 
aloft...middle level forcing...and deep moisture phase. Conditions dry 
and temperature remain cool during Monday afternoon...with 
northwesterly flow aloft present. Zumpfe 


Tuesday through Wednesday...models are in basic agreement during 
this period...with some differences in timing and amplitude of 
features. A weak upper level ridge moves across the forecast area 
Tuesday. Behind this system the upper level flow backs to the 
southwest ahead of an approaching shortwave trough along the West 
Coast. This flow is fairly dry and in conjunction with light 
downslope winds...only a few showers and possibly a thunderstorm or 
two are expected over the northwest and Southwest Mountains...mostly 
Tuesday evening. A warming trend will return temperatures to near or 
a little above seasonal averages. Ek 


&& 


Preliminary point temps/pops... 
gtf 45 76 50 85 / 10 0 0 0 
ctb 43 69 46 78 / 10 0 0 0 
hln 49 78 52 88 / 10 0 0 0 
bzn 41 82 46 89 / 10 0 0 0 
wey 36 72 40 78 / 10 0 0 0 
dln 39 75 44 83 / 10 0 0 0 
hvr 41 77 45 83 / 20 0 0 0 
lwt 42 75 46 82 / 10 0 0 0 


&& 


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


$$ 


Short term...coulston/mpj 
long term...zumpfe/Ek 
aviation...blank 


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