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fxus65 ktfx 191748 
afdtfx 


Area forecast discussion 
National Weather Service Great Falls Montana 
1145 am MDT Friday Mar 19 2010 


..update to aviation... 


Update... 
current forecast is on track...with just a few tweaks. Light snow 
continues in the Bozeman area...and this trend will continue 
through the morning hours...before snow tappers off this 
afternoon. The airmass is becoming slightly unstable over north 
central Montana...and as a weak upper level disturbance moves 
southward from Alberta into north central Montana...a few 
scattered snow showers will be possible between Cut Bank and Havre 
later this morning and through the afternoon hours. A few 
adjustments to temperatures for today...otherwise all else is on 
track. Brusda 


&& 


Aviation... 
updated 1745z. 
The band of snow showers causing occasional MVFR conditions across 
far southwest Montana (kbzn) will decrease through 20z. The 
widespread MVFR cloud deck across the plains of north central and 
central Montana (kctb khvr klwt kgtf) will lift and break up through 
20z...allowing the solar heating to cause areas of instability snow 
showers to form with occasional associated MVFR conditions. These 
instability showers will also form farther south over southwest 
Montana (khln kbzn). An upper level ridge of high pressure will then 
build into the area from the west overnight for clearing skies. A 
surface trough will also form to the Lee of The Rockies...bringing 
increasing southerly winds to the plains area terminals. 
However...winds should become light enough in some of the southwest 
valleys (kbzn) to allow patchy fog to form after 06z. Coulston 


&& 


Previous discussion... 
/issued 630 am MDT Friday Mar 19 2010/ 
today through Sunday...moist northwest flow aloft continues over the 
forecast area early this morning. Will continue with the Winter 
Weather Advisory for Cascade/Judith Basin/Meagher counties as snow 
continues but mainly over the mountains. Will drop the northwest 
portion of the advisory. Also will have the advisory end at 6am 
as snow should generally have ended or become very light by then. 
Snow over southwest Montana..and again mainly over the mountains.. 
should end by late morning. A weather disturbance aloft from 
Canada will move south through the area this afternoon. Models 
show little if any lift with it and the airmass appears stable but 
will continue with isolated to scattered snow showers over the 
mountains. Will drop the mention of precipitation over the plains 
and valleys. Any lingering snow showers over the mountains are 
expected to end by dark. On Saturday a strong upper ridge will 
move into the Pacific northwest and result in a dry day with a 
fair amount of sunshine. The upper ridge will then weaken as it 
moves over the forecast area on Sunday. Expect an increase in high 
level moisture Saturday night and Sunday. Model forecasts are 
generally dry as far as precipitation GOES for Sunday but there 
is a small threat of increased moisture over the Rocky Mountain 
front so will continue with a slight chance of rain/snow showers 
there. Otherwise even with the high level moisture on Sunday low 
levels of the atmosphere are forecast to be dry so expect another 
precipitation free day. With the upper ridge moving into the area 
over the weekend the inherited trend of warming temperatures looks 
good but will be more aggressive with the warming..mainly over the 
plains. Blank 


Sunday night through Saturday...the upper level ridge will dominate 
the area through Monday morning. Models are in good agreement on 
the timing...location and strength of the next system as it makes 
its way onshore over the Pacific northwest Monday. Moisture 
associated with the system will reach central Montana late Monday 
morning and continue to increase throughout the day. Current 
temperatures indicate mountain snow and mixed precipitation over 
the plains and valleys. While most of the energy seems to be 
pushing south towards the Great Basin...northwest flow and 
disorganized waves of energy will pass through western and central 
Montana through Tuesday afternoon. Increased probability of precipitation across portions 
of Montana for Tuesday with likely probability of precipitation in the mountains and 
chance elsewhere. By Tuesday night and Wednesday...a transient 
upper-level ridge should move over the region with drier 
conditions and temperatures around seasonal averages. Models 
diverge from Thursday Onward with multiple shots of light 
precipitation being hinted at. As a result...have stayed pretty 
close to climatology for temperatures and precipitation for the 
end of the extended forecast. 


&& 


Preliminary point temps/pops... 
gtf 32 24 56 35 / 10 0 0 0 
ctb 32 22 56 30 / 20 0 0 0 
hln 36 21 55 29 / 10 0 0 0 
bzn 37 13 47 23 / 100 10 0 0 
wey 33 -5 41 15 / 60 20 0 0 
dln 36 21 49 28 / 20 10 0 0 
hvr 38 18 51 24 / 20 0 0 0 
lwt 33 17 50 28 / 20 10 0 0 


&& 


Tfx watches/warnings/advisories... 
none. 


&& 


$$ 


Weather.Gov/greatfalls