868 
fxus65 kboi 212109 
afdboi 


Area forecast discussion 
National Weather Service Boise Idaho 
309 PM MDT Thursday Aug 21 2008 


Short term...tonight through Saturday...strong pressure gradient 
will relax after sunset allowing gusty north westerly winds to 
diminish. Surface high pressure will be centered over Idaho on 
Friday morning bringing light winds and clear skies. This is an 
ideal set up for efficient radiational cooling... especially in 
places like McCall and Baker City where morning lows will be in 
the 30s. Patchy fog is possible early Friday morning in mountain 
valleys... especially in locations where rain occurred on Thursday. 
Friday will be sunny and mild as the upper level trough moves well 
east of the area. Temperatures will warm back up to several 
degrees above normal on Saturday as an upper level ridge begins 
building back over the area. The NAM and GFS models both hint at 
an area of moisture moving across northern Nevada on Saturday 
afternoon. We are not expecting enough moisture or instability 
north of the border to cause thunderstorm activity except... possibly 
in southern Twin Falls County... where we have indicated a slight 
change of thunderstorms on Saturday afternoon. 


Long term...Saturday night through 
Thursday...upper level ridge will continue to build into the 
intermountain west on Sunday with surface thermal trough setting 
up over the area by Sunday afternoon. Have increased Sunday 
temperatures 3 to 4 degrees as 850-700 mb thicknesses now support 
Treasure valley maximum temperatures in the upper 90s. Cooler 
temperatures and slight chances for showers on Monday as surface 
cold front will transition across the forecast area late 
afternoon/early evening. Models fairly consistent with frontal 
timing...but slight modifications may grossly affect afternoon 
temperatures. Predominantly dry on Tuesday as bulk of moisture 
will exit eastward with surface front. However...slight chances 
for showers remain across higher terrain...mainly east of McCall. 
Temperatures at or below normal Tuesday through Thursday as weak 
northwesterly flow dominates the period. 


&& 


Aviation...isolated MVFR conditions in rain showers will persist 
through 00z this evening...mainly northeast of a line from Baker to 
Idaho City. Light to moderate surface winds with gusts to 30 kts 
through 04z. Moderate to strong westerly winds aloft. After 
06z...widespread VFR with isolated IFR in fog throughout valleys of 
the west central mountains and near kbke. 


&& 




&& 


Aviation... 




&& 


Boi watches/warnings/advisories... 
Idaho...none. 
Or...none. 
&& 


$$ 


Weather.Gov/Boise 


Short term...jb 
long term....Mt/dd 
aviation.....Mt