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Area forecast discussion 
National Weather Service Boise Idaho
256 PM MST Monday Jan 26 2015

Short term...tonight through Wednesday...upper level ridge is
beginning to move east. Temperatures aloft will slowly cool in
response to a system moving up the California coast into the Great
Basin tonight. Patchy fog is expected to form once again tonight
in similar areas as last night. The dense fog that was in the
lower Treasure valley overnight has lifted into a low stratus deck
and could limit fog development under this area. Patchy dense fog
remains in sheltered valleys of Malheur County. Next system
arrives from the south Tuesday afternoon. The strongest dynamics
of this system will move across eastern Idaho into Wyoming...thus
expect the highest precipitation chances in the Magic Valley and
areas eastward with minimal precipitation chances near Baker
County. Snow levels will lower to around 5000 to 6000 feet mean sea level with
this system. Precipitation will move out of the region by
Wednesday morning with patchy fog developing in the sheltered
valley locations of west central and Boise Mountains...and Treasure
and Magic Valleys...as upper level ridging brings warmer temperatures
aloft once again.

Long term...Wednesday night through Monday...transient ridge
Wednesday night will shift eastward. Split flow will then dominate
the northwest but a weak moist upper level trough is now expected over the
area Thursday night to Friday morning. Rex block over western
North America is expected later Friday through Monday...with high
pressure aloft over Idaho and lower pressure over aloft over old
Mexico though model agreement is still low by late Monday with
the operational ec more zonal and the gefs/ensemble ec and 12z GFS
holding on to more ridging. Though disagreement that some moisture
may reach northern tier zones so will have low probability of precipitation across the NE
Oregon/central Idaho mountains late in the extended. Temperatures 5-10
degrees above normal Friday-Sunday and near to a little above
normal early next week.

&&

Aviation...winds and high/middle clouds will increase as an upper low
off the Southern California coast this afternoon lifts across the Great
Basin Tuesday. Expect the main area of stratus and patchy fog to
be across the lower Treasure valley/Weiser basin and Long Valley
tonight through Tuesday. System does not look to totally scour out
the low level moisture so the inversion pattern is expected beyond
Tuesday night. Surface winds southeast to SW 5-15 kts...except in Magic
Valley NE winds 15g30 kts. Winds aloft near 10k feet mean sea level...SW 15-20
kts...through 21z Tuesday.

&&

Air stagnation...continued inversion conditions through Tuesday.
Upper level ridge will begin to break down later tonight as a
trough approaches the area from the south. Inversion will weaken
slightly as cooler temperatures aloft move over the area Tuesday into
Wednesday before a return to inversion conditions later in the
week.

&&

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

&&

$$

Weather.Gov/Boise

Short term...ka
long term....vm/wh
aviation.....Vm
air stagnation...ka

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