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Area forecast discussion 
National Weather Service Boise Idaho
254 PM MST Thursday Jan 29 2015

Short term...tonight through Saturday...we will remain on the far
northern edge of a large upper level low...presently centered
over Southern California...through midday tomorrow...then switch to northwest flow
aloft on the east side of a developing ridge for Friday night and
Saturday. This will keep the area precipitation-free and
strengthen the inversion that has been so prevalent this month.
Most of the fog is gone...but stratus covers much of the lower
elevations areas of east-central Oregon and SW Idaho. This
stratus will move and evolve through Saturday...most likely
filling up the valleys from around midnight to around noon...then
tapering off in the afternoons. Winds will remain light. Outside
of the stratus...skies will be mostly clear.

Long term...Saturday night through Thursday...weak upper level
ridge over the area Saturday night will flatten into zonal flow
Sunday through Monday as a weak upper level trough moves through
the flow. As the ridge flattens on Sunday a chance of
precipitation will develop over northern zones and spread to to
the rest of the forecast area Sunday night and Monday. There are
differences in the models as to timing of precipitation so went
with a model blend. Upper level ridge rebuilds along the West
Coast beginning Monday night and will linger over the area through
the end of the week. Most locations will be dry Tuesday through
Thursday but enough moisture in northwesterly flow over the area
as the ridge builds along the coast will keep a slight chance of
precipitation over the west central and Boise Mountains.
Temperatures through the extended period are expected to remain at
or above normal.


Aviation...high level clouds over the region tonight with mostly
VFR conditions. Local MVFR ceilings in the lower valleys have
persisted into the afternoon and expect this stratus deck to
spread after the sun GOES down...especially in the Snake River
Plain. Thinking that this deck will lower to at least MVFR
conditions tonight but not sure how widespread MVFR ceiling will
be. With the low stratus and high level clouds also uncertain as
to where or if fog will develop. Surface winds tonight will be
light. Winds aloft will be southerly around 10 knots up through
10k feet mean sea level.


Boi watches/warnings/advisories...




Short term...snow pellets
long term....ja/wh

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