902 
fxus65 kggw 160310 aaa 
afdggw 


Area forecast discussion...updated 
National Weather Service Glasgow Montana 
910 PM MDT Wednesday Oct 15 2008 


Short term...for northeast Montana...tonight through Friday... 
a shortwave trough apparent on water vapor imagery is producing 
some precipitation across the absoroka...beartooth...and Big Horn 
Mountains this evening. This precipitation will stay south of 
northeast Montana tonight. Meanwhile...another upper wave is 
producing middle and high level clouds across the County Warning Area. These clouds 
will move east overnight allowing for clearing in the western and 
central zones after midnight. Adjusted sky grids to reflect the 
cloud cover this evening followed by clearing. Also...lowered probability of precipitation 
across the southern zones as the precipitation will stay to the 
south. Adjusted temperatures some in the Missouri breaks region to 
be more representative of a clear stable night. Ajz 


Previous short term discussion... 
a weak shortwave trough will slide east through region tonight. 
Best area for precipitation will be southern Montana and northern 
Wyoming. Currently the leading edge of wave is over eastern Idaho 
where there are some Doppler echoes. So there is a slight potential 
for light precipitation across southern zones tonight. 850mb 
temperatures should remain above 0c in the effected area. However 
surface temperatures will drop below 0c. Since there is a slight 
chance for light rain to freeze on surfaces...will go ahead and bump 
southern zones probability of precipitation to weather/text mention through Thursday morning. 
Enhanced vorticity with the weak upper wave and a surface Lee 
trough nudging in from Canada will make skies mostly cloudy to 
cloudy. In addition...since there is only a slight increase in 
thickness heights...tmax will rise only around 5f Thursday. 


An upper ridge moves over the west Thursday night. The ridge axis 
will remain to the west of NE Montana through the remainder of the 
short term Friday maintaining a northwesterly flow aloft. However 
thermal ridging will increase thickness heights Friday...from 
540dm to 565 in 24 hours. Additionally...increasing sunshine will ramp up 
temperatures to above normal. Highs will climb into the 60s in 
most areas. A surface trough closing in on the western zones will 
enhance mixing there which will make those zones warmer. Areas 
with snow still on the ground could temper local tmax. Scattered 




Long term...Friday night through Wednesday... 
decent consistency exists between the extended models/ensembles...thus 
higher confidence. Friday night into Saturday morning upper 
ridging will make for above normal temperatures and dry 
conditions. Saturday afternoon into Saturday night a cold front 
will sweep across the northern High Plains...making for a few 
showers...stronger winds...and cooler temperatures. Sunday into 
Monday upper ridging will again return for warmer/dryer conditions. 
Monday night into Wednesday a Pacific trough will dig in over the 
area...making for cooler more unsettled conditions. Gilchrist/Hicks 


Previous long term discussion...shortwave ridging over the 
northern High Plains Friday night is quickly replaced by a 
shortwave trough moving into the Pacific northwest Saturday. 
Meanwhile a cold front slides southward from the Canadian 
prairies. Given low amplitude upper flow this shortwave moves out 
of the area very quickly with a cool Canadian high pressure system 
building into the region. However...the 00z European model (ecmwf) and Canadian 
solutions are quite peculiar as they develop a period of 
overrunning precipitation with the front lingering in the area and 
the cooler airmass moving in. Preferred the drier 00z GFS 
solution...which is more consistent with a quasi-zonal flow 
regime. 


By Monday 00z global models and GFS ensembles demonstrate 
reasonable agreement in a more amplified solution with an upper 
ridge building over the area. This ridge is transient in nature as 
it is rapidly replace by an upper trough. GFS and European model (ecmwf) both 
indicate that the upper trough splits keeping any early season 
polar air well to the north. Temperatures should average near to 
slightly above seasonal averages through the extended period. Ajz 




&& 


Aviation... 
VFR. Scattered to broken middle level clouds will slowly build in 
from the west. Surface winds will generally be less then 08kts 
from the southeast...with the exception of kggw where a bit 
stronger winds can be expected. Gilchrist/Hicks/Simonsen 


&& 


Glasgow watches/warnings/advisories...none. 


&& 


$$ 


Weather.Gov/Glasgow