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fxus65 ktfx 062019 
afdtfx 


Area forecast discussion 
National Weather Service Great Falls Montana 
219 PM MDT Sat Sep 6 2008 


Discussion... 
today through Monday evening...persistent longwave trough centered 
over the Great Plains still extending back through Montana and into 
BC/alb. Series of shortwave troughs embedded in the large-scale 
northwesterly flow continue to streak southeastward across the County Warning Area...helped 
by 120 miles per hour jet stream overhead this afternoon...with pockets of Pacific 
moisture accompanying each trough. Moisture coverage is a bit more 
spotty than past few days...making for more isolated rainshowers this 
aftn/eve...with a few brief marginal thunderstorms between Havre and 
Lewistown. WV satellite imagery shows at least two more shortwaves 
upstream and those should arrive tomorrow for hopefully the final 
round of precipitation. Models are cautiously optimistic that the 
longwave trough will finally slide eastward enough to allow drier airmass 
associated with large upper ridge centered near 130w to reach our 
area on Monday and produce gradually clearing skies. Temperatures will 
remain well below normal today and tomorrow as models show no 
appreciable temperature advection thanks to the northwest flow aloft. Decreased 
clouds will allow temperatures to rebound upward on Monday but still be 
5-7 degree below normal. Waranauskas 




Monday night through Thursday night...the extended forecast period 
will be characterized by persistent northwesterly flow aloft across 
the region. Initially...a fairly stationary hemispheric upper level 
pattern exists...with a ridge of high pressure camped out in the 
Gulf of Alaska. By Tuesday afternoon...upper level features will 
likely become Mobile...with a weak upper level trough dropping into 
the region from the Canadian rockies. Current guidance depicts this 
trough developing into a closed circulation as it approaches the 
forecast area...at a slower speed and with a colder core aloft 
compared to guidance yesterday. Precipitation producing features 
appear less impressive during this time as well. Consequently... 
expectations for precipitation have been reduced during the Tuesday 
through Wednesday period...and Wednesday afternoon temperatures 
decreased...as compared to previous forecast. Temperatures quickly 
rebound on Thursday...as the ridge of high pressure in the Gulf of 
Alaska moves eastward over the Pacific northwest. There appears to 
be vast disagreement among current guidance concerning the evolution 
of the upper level features in the region as a more progressive 
hemispheric pattern emerges. Zumpfe 




&& 


Aviation... 
updated 1750z. 
Moist and somewhat unstable northwest flow aloft will continue to 
bring weak disturbances over the area. Low ceilings and areas of 
precipitation will gradually improve this afternoon but return again 
after 00z. VFR conditions prevail with MVFR condition in the 
vicinity of showers. MVFR conditions will prevail after 00z due to 
low ceilings and precipitation. 


&& 


Preliminary point temps/pops... 
gtf 43 55 37 66 / 50 60 20 0 
ctb 42 53 36 64 / 40 50 20 0 
hln 45 58 39 70 / 30 50 20 0 
bzn 39 60 38 72 / 20 40 20 0 
wey 35 59 32 68 / 20 30 10 0 
dln 39 63 36 72 / 10 30 10 0 
hvr 40 59 38 66 / 20 30 20 0 
lwt 40 51 34 62 / 50 60 30 10 


&& 


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


$$ 


Short term...waranauskas 
long term...Emanuel/zumpfe 
aviation...Emanuel 


Weather.Gov/greatfalls