Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 131033

Area Forecast Discussion
National Weather Service Boise ID
333 AM MST Wed Dec 13 2017

.SHORT TERM...Today through Thursday...A weak upper wave moving
through the Pacific NW is tracking further south than previous
forecasts, and will cross through central Idaho by early
afternoon. This will bring some light snow to the east-central
Oregon and west-central Idaho mountains through the day.
Accumulations will generally be less than inch. The increase in
moisture aloft could help to seed the lower stratus adding to the
potential for very light snow (flurries). The upper low is well
east of the area by evening, returning dry conditions for tonight
and Thursday. Don`t expect much change in the stratus/fog field
today, with further expansion possible in southeast Oregon tonight
into Thursday as skies clear aloft. Mid-upper level cloud cover
and the passing wave will act to cool temperatures in the
mountains around 5 degrees from yesterday. Lower valleys will see
little change in temperatures through Thursday.

.LONG TERM...Thursday night through Tuesday...Models all in good
agreement in showing the upper ridge finally breaking down as a
weak front pushes into the Pacific Northwest late Friday. The best
threat of precipitation should remain north of a Boise and Burns
line in the afternoon then across majority of the forecast area
Friday night...but not expecting much in the way of snow
accumulations. A combination of stronger winds and the associated
cold front should scour out the inversion Friday afternoon and
evening. Warmer temperatures on tap for the lower elevations that
have been encased in the fog/stratus for the last days days or so.

The models also indicating an upper ridge remaining off the West
Coast for the remainder of the weekend and into the first half of
next week.  Although not as highly amplified as before...this ridge
should focus the jet stream and thus precipitation across Washington
and Idaho Panhandle. POPS have been lowered across the region in
response to this ridge. Temperatures should be at or slightly above
normal for early next week. Potential big changes possible mid to
late next week as another system drops into the region in a more
northerly flow, but models are not consistent with its path at this


.AVIATION...Low stratus and fog in the lower valleys
continuing to cause MVFR/IFR conditions.  Cant rule out a stray snow
flurry across from KONO through KTWF this afternoon in this stratus
deck. Otherwise mid/high clouds spread over the region assoc with
weak feature today. Light snow showers also possible near KMYL in
response to this weak feature. Surface winds: light and variable.
Winds aloft at 10 KFT MSL: variable 5-15 kts.


.AIR STAGNATION...There will be little change in the inversion through
at least Friday when a cold front tracks across the region.


ID...Dense Fog Advisory until 11 AM MST this morning IDZ014-016-030.



AIR STAGNATION...DG is the U.S. government's official web portal to all federal, state and local government web resources and services.