Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 301517
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
917 AM MDT TUE AUG 30 2016

.DISCUSSION...Extensive mid/high clouds over Oregon and southwestern
Idaho will hold temps down most of today, but models show clearing
from the southwest late today and temps may spike.  Latest HRRR puts
102 degrees on Boise around 6 PM MDT after keeping the area cloudy
until 3 PM.  Other models are not that warm, but south or southeast
surface winds all day will also help boost temps.  For now we will
stay with current forecast on the cool side of guidance.  Southwest
surface winds up to 30 mph will blow in Harney and southern Malheur
Counties this afternoon.  Southwest winds will also blow aloft in
all areas today, including above the Pioneer fire which grew quite
a bit since Monday.  Slight chance of thunderstorms late this
afternoon/evening in northeast Oregon and the west central Idaho
mountains, and Wednesday afternoon in our eastern-most Idaho zones,
already in our forecasts.  No updates for now.

&&

.AVIATION...VFR. Areas of MVFR/IFR conditions in and around
wildfires. Increased mid-upper level clouds pushing in from the
southwest and moving northeast. Isolated showers/thunderstorms in
Baker County. Surface winds, variable 5-10 kts with gusts picking up
this afternoon, southwest 15-25 kts with higher gusts possible in
and around thunderstorms/showers. Winds aloft to 10k feet MSL, south-
southwest 15-35 kts.

&&

.PREV DISCUSSION...
SHORT TERM...Today through Wednesday...Long wave trough continues
to dig south along 140W with the axis of this trough shifting over
the forecast area by the end of the week. A weak shortwave
rotating around the base of the trough is off the northern
California coast this morning and will move northeast over Oregon
and Washington today. Models continue to back off on how much
precipitation will be with this system, but decided to leave at
least isolated showers and thunderstorms over the higher terrain
of Baker County and the West Central Mountains for this afternoon
into this evening. Other forecaster challenge for today will be
high temperatures. Due to cloud cover spreading over the region
ahead of the upper level trough, and combined with moisture from
tropical storm Madeline east of Hawaii, thinking high temperatures
will not be as warm today as model guidance suggest. High
temperatures on Monday were a few degrees cooler than forecast due
to the cloud cover, so have backed off on high temperatures for
today by a few degrees from previous forecast. As the axis of the
upper level trough approaches the west coast Wednesday, will see
mostly dry conditions over the forecast area, but enough moisture
in the southwesterly flow for slight chance of showers and
thunderstorms Wednesday afternoon over Southern Twin Fall County,
Western Magic Valley and the Camas Prairie.

LONG TERM...Wednesday night through Monday...Southwesterly flow
ahead of an upper level trough off the British Columbia coast will
continue through Friday with a stationary cold front situated over
central OR/WA. The upper level trough pushes inland over southern BC
on Friday morning and the cold front will move across SW Idaho and
SE Oregon. Any precipitation that does fall will be confined
generally north of a Baker City to McCall line, much like the ECMWF
solution. Cool and dry northwest flow continues on Saturday through
Monday with dry conditions expected and temperatures around 5-10
degrees below normal.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Red Flag Warning from 2 PM this afternoon to 9 PM MDT this
     evening IDZ401>403-421-423-424-426.
OR...Red Flag Warning until 9 PM MDT /8 PM PDT/ this evening
     ORZ636-637-646.

&&

$$

www.weather.gov/Boise
www.facebook.com/NWSBoise
www.twitter.com/NWSBoise

DISCUSSION...LC
AVIATION.....JC
PREV SHORT TERM...JA
PREV LONG TERM....KA



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