866 
fxus65 kboi 300923 
afdboi 


Area forecast discussion 
National Weather Service Boise Idaho 
323 am MDT Sat Aug 30 2008 


Short term...today through Sunday...a strong upper level system 
will move into the Pacific northwest today and impact our County Warning Area into early next 
week. This will result in rapid temperature changes as a cold 
front sweeps through late this afternoon into tonight. 
Temperatures will shoot up today in advance of the front...much 
like they did this past Monday. Strong winds will move through 
this evening...with blowing dust likely over the Treasure valley 
and surrounding regions. This wind event will not be as strong as 
the Monday event...and because the strong winds will be confined 
to a short time period just after frontal passage...it will not 
meet the criteria of even a Wind Advisory. However...we will 
continue the Special Weather Statement that was issued yesterday to highlight these short- 
duration significant winds. Elsewhere...moisture from the monsoon 
flow will be confined to southern Twin Falls County this 
afternoon and evening...and there is a slight chance of 
thunderstorms in that area. In addition...over the higher terrain 
of our northern County Warning Area...there is a slight chance of thunderstorms 
late this afternoon and overnight along and near the front. After 
the front moves through...the upper level system will slow down 
considerably as a strong short wave moves down the back side of 
the trough. This will keep a chance of showers and thunderstorms 
over the west central and Boise Mountains through at least Sunday. 


Long term...Sunday night through Friday...an additional upper 
level low will drop south out of Canada into the region Sunday 
night/Monday. Models continue to differ in the placement and 
handling of this low. GFS continues to place the low just south of 
the County Warning Area over northern Nevada...while the European model (ecmwf) continues to place 
the low over the County Warning Area. Models continue to be consistent with 
keeping the bulk of the monsoon moisture east of the County Warning Area on 
Monday...although moisture will wrap around the upper level low 
during this period...keeping a slight chance of probability of precipitation in the 
forecast...mainly in the Idaho zones. Models agree that the upper 
level low will move out of the County Warning Area Monday night/Tuesday...although 
inconsistencies still exist in the timing and placement of this 
system as it exits the region. Models continue to indicate a 
series of shortwaves...and possibly another closed low dropping 
south out of Canada into the County Warning Area through at least Friday. Have 
continued to maintain previous forecast of below normal 
temperatures and above normal probability of precipitation to account for this. Models 
indicate upper level ridging returning to the region late in the 
period. 


&& 


Aviation...VFR conditions with scattered to broken high clouds. 
Light surface winds with light to moderate SW winds aloft. MVFR 
visibilities in vicinity of wildfires...including near Jackpot 
Nevada...Picabo and Featherville Idaho. A cold front will move 
into the region Saturday afternoon. This will create gusty northwest 
winds...and reduced visibilities due to blowing dust. Isolated 
thunderstorms will also be possible in Baker County Oregon...the 
central mountains of Idaho...and along the Idaho/Nevada border. Gusty northwest 
winds...scattered showers and isolated thunderstorms will remain 
across the region for Sunday. 


&& 


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


$$ 


Weather.Gov/Boise 


Short term...snow pellets 
long term....sl 
aviation.....Sl