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fxus65 ktfx 110012 
afdtfx 


Area forecast discussion 
National Weather Service Great Falls Montana 
515 PM MST Wednesday Mar 10 2010 


Discussion... 


Tonight through Friday...system that brought snow to southwest 
Montana overnight continues to pull away from the forecast area. Am 
expecting residual clouds and scattered showers to linger across 
eastern portions of southwest Montana overnight. There could also be 
some early evening showers across portions of central Montana as 
weak instability showers formed from afternoon heating slowly 
dissipate across the region. Overnight temperatures will be quite 
cool once again and have opted to mention patchy fog in river 
valleys across much of the forecast area. However...an upper level 
ridge will be working its way into western and central Montana 
overnight with mostly clear skies prevailing across the region and 
light southwest winds developing across the north Central Plains. A 
weak shortwave works its way across Montana on Thursday helping to 
develop a surface trough in Alberta for increasingly gusty downslope 
winds east of the Continental Divide. The upper ridge over the 
region is expected to nose over...becoming positive tilt by Friday 
with a fast and moist southwesterly flow aloft setting up over the 
Pacific northwest. Main impact to my forecast area will be an 
increase in clouds with a Chinook Arch likely setting up over 
western portions of north central Montana. Orographic lift is also 
expected to squeeze out scattered snow showers over the Glacier park 
region Thursday night and Friday. After a cool night tonight... 
temperatures will warm back up to well above seasonal averages by 
Friday. Mpj 


Friday night through Monday night...high pressure ridge that was 
over central Montana on Friday moves into eastern Montana overnight 
Friday while Pacific shortwave trough makes steady eastward progress 
through eastern Washington/or and northern Idaho. Leading edge of clouds and 
precipitation associated with the trough reach the Rocky Mountain front and 
Southwest Mountains around midday on Sat...bringing light valley Rain/Mountain 
snow. After seeing marked differences in GFS and European model (ecmwf) models 
handling of this weather system past few days...00z model runs 
finally showed good agreement with the GFS trending toward the 
European model solution to drive the trough southward into Utah by 
midnight on Sat. This will keep the bulk of the precipitation 
across southwest and south central parts of the state...although 
Central Plains locations may see some spotty rain/snow mix on Sat 
aftn/eve. The system exits the Great Falls County Warning Area by Sun morning...as 
fairly strong Pacific Ridge builds back into the region by sun evening. 
Ridge will cover most of the Great Basin and northern rockies on 
Monday...bringing mostly clear skies across the County Warning Area. Area will see 
a short-lived cooling trend in temperatures on Sat/sun as sharp 
surface cold front sweeps across the region on Sat. Look for temperatures 
to warm back to 8 to 10 degree above normal on Monday. Waranauskas 


Tuesday and Wednesday...a ridge is in place on Tuesday and looks to 
slowly drift east through Wednesday as a low pressure system begins 
to influence the Pacific northwest. Temperatures should be 
relatively warm and winds should be fairly light. 


&& 


Aviation... 
updated 0015z. 
Expect VFR conditions. Skies will clear overnight. Do not expect 
much threat for fog formation except possibly in selected river 
valleys. At the taf sites it appears there will be a small threat of 
freezing fog late tonight and early Thursday morning at khvr but 
think the threat is small enough that did not mention it in that taf 
forecast. Blank 


&& 


Preliminary point temps/pops... 
gtf 24 49 33 58 / 0 0 0 0 
ctb 20 47 28 56 / 0 0 0 0 
hln 21 48 28 54 / 10 0 0 0 
bzn 16 43 21 49 / 20 0 0 0 
wey -1 34 10 41 / 30 0 0 0 
dln 17 42 24 48 / 10 0 0 0 
hvr 10 36 16 39 / 10 0 0 0 
lwt 20 43 27 53 / 10 0 0 0 


&& 


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


$$ 


Weather.Gov/greatfalls