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fxus65 ktfx 062057 
afdtfx 


Area forecast discussion 
National Weather Service Great Falls Montana 
257 PM MDT Monday Oct 6 2008 


Discussion... 
tonight through Wednesday...an upper ridge over the forecast area 
this evening will move into eastern Montana late tonight. Expect 
increasing cloudiness overnight on the heels of the upper ridge. 
With the influence of the upper ridge do not expect any 
precipitation this evening. Per the current forecast it still looks 
like there could be a few showers over the mountains of the Rocky 
Mountain front by sunrise Tuesday. On Tuesday a fast-moving weather 
disturbance aloft will zip through the northern zones. Associated 
with this a cold front will move southeast through the forecast area 
during the day. There will be very strong low level downslope near 
and behind the front. With the models being consistent with this 
idea have upgraded the high wind watch to a high warning warning for 
Tuesday into Tuesday evening. Forecasting the threat of 
precipitation with tuesdays weather system will be somewhat 
difficult. There will be some moisture and lift and maybe even some 
weak instability. On the other hand strong downslope could limit the 
threat of precipitation. Decided to mention a threat of light rain 
showers or sprinkles for portions of the plains. With the moist and 
strong westerly flow aloft..western mountains will likely receive 
some rain and snow. Late Tuesday into Tuesday evening drier air will 
move in over the plains but some moisture could linger over 
southwest Montana and the mountains of the Rocky Mountain front. 
Wednesday expect dry northwest flow with afternoon temperatures 
about 10 degrees cooler than those of Tuesday. Blank 


Wednesday night through Thursday...a Pacific cool front will 
continue to push through the region resulting in cooler air moving 
into the region for Thursday afternoon. A weak upper level 
disturbance also moving through will allow for a few mountain 
showers...especially over the Rocky Mountain front. 


For Thursday night through Saturday night...both the GFS and European model (ecmwf) 
continue to disagree on the potential snow storm that could affect 
the region. The GFS has a band of snow showers moving through the 
area Thursday night into Friday morning...then pretty much dry and 
milder conditions for Saturday. The European model (ecmwf) however has a closed upper 
level low over the region Friday and Saturday...along with much 
colder temperatures...and a strong surface low developing over the 
central rockies. This scenario would result in heavy snow over 
portions of central and southwest Montana. For now have trended 
towards the GFS but kept in a small chance for showers and kept 
temperatures below GFS guidance...and on the cool side. However this 
system needs to be watched closely over the next few days...because 
if the European model (ecmwf) pans out...the first significant snow storm will affect 
portions of central and southwest Montana this weekend...with heavy 
snow and much below normal temperatures. Brusda 


Sunday and Monday...models not in very good agreement. 
However...most models do show a long wave trough over the upper 
Midwest with upper level ridge across the Pacific northwest. 
Will go with the GFS model...but keep temperatures lower on Sunday 
as GFS model generally move systems out too fast. Thus...will delay 
the warmup until Monday. It will be mostly dry with only scattered 
rain or snow showers across the Continental Divide. Sunday will 
still be cool with temperatures warming to near seasonal average by 
Monday. Williamson District of Columbia 


&& 


Aviation... 
updated 1745z. 
VFR conditions to continue across most of north 
central...central...and southwest Montana through at least 18z 
Tuesday. A band of middle level clouds and isolated rain showers over 
far north central Montana (including the khvr terminal) will 
dissipate through 21z today. Otherwise...an upper level ridge of 
high pressure will build into the area from the southwest through 
the period...as middle level clouds with isolated rain/snow showers 
will obscure mountain tops across western and southwest Montana. 
Gusty west surface winds will also persist across the area through 
the day...before decreasing overnight. Middle level cloudiness and 
mainly mountain showers will increase overnight into Tuesday morning 
as a disturbance approaches the area from the west...which in turn 
will obscure mountains at times. Westerly winds will also increase 
again Tuesday morning...especially along the east slopes of The 
Rockies...as the disturbance moves through the area. 


&& 


Preliminary point temps/pops... 
gtf 42 67 38 55 / 0 10 10 0 
ctb 40 63 35 52 / 0 10 0 0 
hln 40 67 38 57 / 0 10 10 0 
bzn 36 71 35 58 / 0 10 0 0 
wey 29 56 30 53 / 0 10 10 10 
dln 38 65 36 55 / 0 10 10 0 
hvr 35 69 35 57 / 0 10 0 0 
lwt 36 67 35 54 / 0 10 10 0 


&& 


Tfx watches/warnings/advisories... 
High Wind Warning from 6 am to 9 PM MDT Tuesday for mtz009-010- 
044-046-048-049. 


&& 


$$ 


Short term...blank 
long term...coulston 
aviation...coulston 


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