Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 212041

Area Forecast Discussion
National Weather Service Boise ID
241 PM MDT Fri Jul 21 2017

.SHORT TERM...Tonight through Sunday...Dry westerly flow aloft
will continue the mostly clear skies and temperatures near normal
through Saturday. The upper level ridge begins to rebuild on
Sunday with bringing warmer temperatures and increase high level
moisture. Temperatures will warm about 4 to 6 degrees above

.LONG TERM...Sunday night through Friday...A dry hot air mass on
Sunday will transition to a moist and unstable air mass starting on
Sunday night as a trough off the California coast brings a surge of
monsoon moisture from the south. Thunderstorms are expected in SE
Oregon and along the ID/NV border an Sunday night, spreading across
the region on Monday. Precipitable waters reach 1.00-1.25in by
Tuesday, which is quite high (in the 95-97th percentile), meaning
thunderstorms will contain heavy rain with flash flooding concerns
on past burn scars, like the Pioneer Fire. Dewpoints may reach 60F
degrees in the Snake Plain on Tuesday. Scattered thunderstorms are
expected areawide on Tuesday with favorable CAPE values and high
shear creating a favorable environment for strong storms into
Wednesday. Models have been trending slower with the passage of this
trough off the CA coast, which may keep a chance of afternoon
thunderstorms through Thursday night before the system passes to the
east, and the monsoon moisture tap is shut off. Models agree in a
drier west-southwest flow aloft arriving by the end of next week.
Slightly above-normal temperatures are expected Tuesday through
Friday, although cloud cover could keep temperatures lower on
Tuesday and Wednesday.


.AVIATION...VFR with clear skies. Smoke layers. Variable surface
winds up to 10kt. Winds aloft near 10k ft MSL: westerly 5-15kt.

Weekend outlook...VFR with mostly clear skies and light winds. Smoke
layers at times. Increasing clouds with a slight chance of
thunderstorms on Sunday evening in SE Oregon and along the ID/NV





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