FXUS65 KBOI 212049

Area Forecast Discussion
National Weather Service Boise ID
249 PM MDT Mon Aug 21 2017

.SHORT TERM...Tonight through Wednesday...Dry conditions expected
through Tuesday morning, with light wind and warming temperatures.
An area of low pressure off the coast of California will push
moisture across Nevada and into southern OR/ID Tuesday. This will
bring unsettled conditions with the threat of showers and
thunderstorms by Tuesday afternoon. Meanwhile, the ridge axis will
slide to the east, allowing additional Pacific moisture and
instability to impact the area. This will leave slightly cooler, and
generally unsettled conditions across the area through Wednesday
afternoon with continued showers and thunderstorms. Models are in
fair agreement that the most shower coverage is anticipated to occur
Wednesday afternoon.

.LONG TERM...Wednesday night through Monday...A cold front
will cross eastern Oregon and southwest Idaho Wednesday night as an
upper level trough from the Gulf of Alaska moves inland over British
Columbia. The front will trigger thunderstorms in the moist and
unstable monsoon air over our area. Instability will decrease
following the front, but surface heating on Thursday is expected to
set off isolated afternoon and evening thunderstorms. Only a slight
chance of measurable rain is expected at most lower elevation
locations. As the trough moves east of the Rockies Thursday night,
subsidence and cooler drier air will hinder thunderstorm development
across our area, and Friday is expected to be mostly sunny. The
upper level ridge will rebuild over the western U.S. over the
weekend, bringing a warming trend and mostly clear skies Saturday
through Monday.


.AVIATION...VFR with mostly clear skies. Expect smoke layers over
the central Idaho mountains east of KMYL. Surface winds will be
variable 10 kts or less. Winds aloft near 10k ft MSL will be mainly
from the west 5-15 kts.


ID...Fire Weather Watch from Wednesday afternoon through late
Wednesday night IDZ400>403-421-423-426.
OR...Fire Weather Watch from Wednesday afternoon through late
Wednesday night ORZ636-637-646.




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