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fxus65 ktfx 082352 
afdtfx 


Area forecast discussion 
National Weather Service Great Falls Montana 
445 PM MST Thursday Jan 8 2009 


Aviation section updated... 


Short term (tonight through Friday night)... 


Complicated surface pattern across the region...slow moving boundary 
pushing to the east out of Blaine County as surface low moves along the 
Canadian/US border across northeast Montana...cold front pushing south 
across the border with 15 to 25 degree temperature drops in less 
than a half of an hour recorded in southern Alberta and at 
Sweetgrass just inside the border north of Cut Bank. Decent pressure 
gradient across the region will allow for the moderate wind to 
continue into the night. Precipitation will have moved out of Blaine 
County...will end the Ice Storm Warning. 


Cold front will continue to push into the forecast area early this 
evening and into tonight. Snow will develop mainly behind the front 
as multiple shortwaves will push across the forecast area. More of 
an impact will be felt across the northern half of the region...will 
continue the Winter Weather Advisory there for 2-5 inches of snow 
along with blowing and drifting expected with the northerly winds of 
15 to 25 miles per hour. Time height series and forecast soundings would 
suggest that a decent period of forcing and moisture will come 
together mainly between 00-09z across the area. Have bumped up probability of precipitation 
to categorical...near 90+ percent across the northern half...with 
likelies(60-70 percent) south outside of higher probability of precipitation in the higher 
elevations. Wind chills may approach -15 or -20 during the early 
morning hours Friday. 


Surface high will push into the region behind the system...ending most 
of the precipitation if not all by midday. Highs much cooler for Friday. 
Surface high pressure and west northwest flow will dominate the region 
into the weekend. Winds may increase slightly overnight Friday into 
Saturday with 15 to 20 and gusts to around 30 miles per hour across the 
northern Rocky Mountain front and around Great Falls and into the little 
belt mountain area. The winds may cause temperatures to slowly rise through the 
overnight due to the downslope warming. 


Long term (saturday through thursday) 


Saturday and Sunday...northwest flow will continue and a broad 
Pacific Ridge should keep temperatures relatively warm across 
central Montana. The exact position of the ridge will determine 
whether or not we see some effects of an Arctic air mass moving 
south from central Canada however. There is a possibility of light 
snow Sunday...mainly near the Rocky Mountains and higher 
elevations...as some moisture moves across the region from the 
northwest. 


Monday through Thursday...an upper level high pressure ridge over 
the eastern Pacific and West Coast will remain fairly stationary 
until moving east over the Pacific northwest on Wednesday. This will 
keep the local area underneath unsettled...northwest flow aloft. The 
airmass will be quite moist Monday as a shortwave moves through the 
flow aloft and...at the surface...high pressure over Saskatchewan 
and eastern Montana will bring upslope flow across the plains. 
Drying will begin by Monday night but improvement in the east will 
be slow. The gradual movement of the ridge east will keep most of 
the region free from higher chances of precipitation...the northeast 
zones will have the best chance for precipitation as they remain along the 
boundary between the colder air to the northeast. Temperatures will remain 
near normals through the period. Zelzer/db 


&& 


Aviation... 
updated 08/2345z. 
Sharp upper level low pressure trough making its way across western Montana 
this afternoon with leading surface cold front currently south of 
kctb/khvr. Cold front will continue to move steadily south this evening 
causing quick shifts to north-northwest winds and rapid drop in 
temperatures. Current radar shows not much snow along the front but 
expect broad area of snow to develop behind the front and spread 
southward as well tonight. Ceilings/visibilities will drop to MVFR 
and IFR categories as the front tracks across the region and wind 
gusts of 20 to 30 kts will create intermittent blowing snow at local 
airfields. Forecast models in good agreement that weather 
system will make steady progress overnight with conditions gradually 
improving back to VFR from north to south starting late Friday 
morning. Widespread mostly clear skies are forecast for Friday 
aftn/eve. Waranauskas 




&& 


Preliminary point temps/pops... 
gtf 13 31 25 39 / 90 30 0 10 
ctb 4 29 22 34 / 90 10 0 20 
hln 24 37 20 39 / 90 20 0 10 
bzn 24 36 13 38 / 70 30 0 0 
wey 13 24 0 24 / 90 50 20 10 
dln 22 28 10 37 / 60 10 0 10 
hvr 0 21 12 34 / 90 20 0 0 
lwt 12 28 15 39 / 90 40 0 0 


&& 


Tfx watches/warnings/advisories... 
Winter Weather Advisory from 6 PM this evening to 5 am MST Friday 
for mtz009>013-044>051. 


Winter Storm Warning until 5 am MST Friday for mtz009-048. 


&& 


$$ 


Short term...schott 
long term...zelzer/db 
aviation...db 


Weather.Gov/greatfalls