631 
fxus65 kboi 022144 
afdboi 


Area forecast discussion 
National Weather Service Boise Idaho 
244 PM MST Tuesday Dec 2 2008 


Short term...tonight through Thursday...northwest flow aloft will 
persist overnight before giving way to a moderate but fairly dry 
impulse moving in from the north early Wednesday. This impulse 
will bring in more cloudiness and a chance of snow showers to the 
higher elevations tomorrow. In the meantime...tonight will be 
mostly cloudy to the north and partly cloudy to the south. Winds 
will continue out of the northwest as high pressure continues to 
build into the area. Fog formation should be limited by both the 
cloud cover and just enough wind...but patchy fog should still 
form in and near the lower Treasure valley and in the mountain 
valleys that received rain or snow today. Temperatures will be above 
normal even with the passage of another system tomorrow. We will 
see highs 5 to 10 degrees above normal in most areas Wednesday... 
with readings near or about 5 degrees above normal Thursday. There 
will continue to be a chance of showers in the west central and 
Boise Mountains through Thursday as moisture continues to flow 
over that area. The valleys will be mainly dry. The Wind Advisory 
for the western Magic Valley and southern Twin Falls County will 
expire at 5 PM this afternoon. So far...winds have gusted between 
30 and 40 miles per hour. These gusts will weaken after sunset. 


Long term...Thursday night through Tuesday...model agreement and 
run to run consistency are good early in the period with an upper 
level ridge over our area Friday and Saturday...then a weak upper 
level trough moves through Sunday and Sunday night. For Monday 
through Tuesday most models want to transition to zonal flow...with 
differences in timing of features. The Canadian on the other hand 
wants to use Sunday/S shortwave trough to carve out a very deep 
longwave trough over the west by 00z Tuesday. Other model runs have 
been hinting at some retrogression but not that soon...and latest 
runs of the GFS and European model (ecmwf) bring the longwave trough no further west 
than the plains states. We are keeping Thursday night through 
Saturday dry under the ridge...transitioning into above climatology 
probability of precipitation for Sunday with the shortwave trough...then near climatology 
for the less certain periods after that. Temperatures are 5-10 
degrees above normal through the period. 


&& 


Aviation...areas of mountain obscuration and snow showers will 
continue tonight over the west central mountains mainly east of 
kmyl...and the Boise Mountains. Patchy IFR fog is expected to re- 
form in the upper and lower Treasure valleys...the Long Valley... 
and the kmyl area after 06z and persist until about 18z Wednesday. 
Otherwise conditions will be VFR except for widely scattered snow 
showers over the mountains north and east of kboi. Surface winds 
will be moderate westerly in the Magic Valley this evening...but 
otherwise light northwest through Wednesday. Winds aloft will be 
moderate northwest. 




&& 


Boi watches/warnings/advisories... 
Idaho...Wind Advisory until 5 PM MST this afternoon for idz016-idz030. 
Or...none. 
&& 


$$ 


Weather.Gov/Boise 


Short term...snow pellets 
long term....jt/sl 
aviation.....Jt