938 
fxus65 kboi 212205 
afdboi 


Area forecast discussion 
National Weather Service Boise Idaho 
305 PM MST Sat Nov 21 2009 


Short term...tonight through Monday...winds will build tonight 
from the southeast and south then shift to SW and northwest Sunday behind 
a fast moving cold front. Huge... to +10/+15 mb pressure 
fall/rise couplet stays to our northwest and north for locally very windy 
conditions across southeast Oregon and breezy areas for SW Idaho...but no 
headlines for wind. Snow and areas of blowing/drifting snow are 
expected with this fast moving system Sunday so an advisory for 
snow and blowing snow has been hoisted across Baker County...the 
west central and Boise Mountains. Gusty northwest winds diminish rapidly 
Monday night as high pressure builds in...with light winds and 
mostly clear skies. Coupled with new snow cover...generally above 
3500 feet...low temperatures will plummet to single digits coldest spots 
such as Fairfield and middle 20s...teens across the relatively milder 
locales. Light winds and a cold start Monday look to keep temperatures 
below normal and near to below MOS. 




Long term...Monday night through Saturday...upper ridge builds into 
the Pacific northwest on Tuesday. Weak system moving through the Panhandle 
Tuesday afternoon will do little more that increase clouds over the 
west central mountains with warming aloft...inversion sets up in the 
lower elevations for Tue/Wed. Introduced fog into the forecast for 
Tuesday night and Wednesday in the lower Treasure...Weiser and Baker 
valleys. Less confident on development of fog/stratus over Boise 
Wednesday morning so have left it out for now. Good model agreement 
that inversion is short-lived...as another storm enters the Pacific northwest 
late in the week. The 12z solutions are in better agreement on 
bringing the storm through the intermountain northwest on Friday. Winds 
ahead of the system would likely clear out any fog/stratus in the 
lower valleys Thanksgiving day. Looks like rain in the valleys on 
Friday with mountain snow. Pattern remains active through next weekend. 


&& 


Aviation...widespread IFR conditions in snow developing Sunday 
morning...over southeast Oregon after 06z and SW Idaho after 09z. Will see 4-6 
hours of IFR conditions at Boise Sunday morning. IFR conditions 
continue in SW Idaho mountains and western Magic Valley through Sunday 
afternoon. Conditions improve to VFR in southeast Oregon and Treasure 
valley of SW Idaho Sunday afternoon. Gusty southeast surface winds early 
Sunday morning shifting to the west in the afternoon. Strong 
westerly winds aloft of 40-60 kts on Sunday. 


Outlook...development of inversion next week will bring chance of 
IFR conditions in fog/stratus to Treasure/Baker/Weiser valleys on 
Wednesday. 




&& 


Boi watches/warnings/advisories... 
Idaho...Winter Weather Advisory from 4 am to 2 PM MST Sunday for idz011- 
idz013. 
Or...Winter Weather Advisory from 1 am to 10 am PST Sunday for orz062. 
&& 


$$ 


Weather.Gov/Boise 


Short term...vm 
long term....dg/dd 
aviation.....Dg