Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 181932

Area Forecast Discussion
National Weather Service Pocatello ID
132 PM MDT Fri Jun 18 2021

.SHORT TERM...Tonight through Sunday night. WV imagery indicates a
surge of mid-level moisture aimed at our southern border this
afternoon. Strong high pressure remains anchored over the Four
Corners area with ridging mostly flattened across the western US.
We`re watching a shortwave in northern BC as models suggest it will
begin to drop to the southeast tomorrow night and Sunday.
Statistical guidance is indicative of some stronger winds tomorrow
afternoon, giving us lake wind concerns as well as red flag concerns
(see FIRE WEATHER below). We should see some stronger winds over the
Arco Desert/Mud Lake area tomorrow, adding wind advisory conditions
to that zone.

Back to the disturbance currently in British Columbia--models show
this dropping to the southeast tomorrow night while we see cooler
temperatures filter into the region with Sunday highs about 5 to 10
degrees cooler than Saturday. The disturbance should stay to our
east, but it may induce some showers/thunderstorms in the Island
Park area by Sunday afternoon. Winds should shift to the north
Sunday afternoon with high pressure settling in over western MT.

.LONG TERM...Monday through next Friday. The ridge of high pressure
will rebound across the Western Great Basin and Oregon Monday for a
dry and mild day across SE Idaho. The ridge axis shifts east Tuesday
as a low pressure trough sets up over the NRN California coast. The
models have been fairly consistent with the idea that a disturbance
will eject from the low into the ridge axis late Tuesday afternoon
and evening providing the necessary lift and moisture for
thunderstorm activity over the CNTRL mountains. Breezy afternoon
winds are also expected across the Snake River Plain Tuesday
afternoon. The ridge breaks down further Wednesday and shifts east
of the divide while a broad open trough lingers across Oregon and
NRN California supportive of broader thunderstorm coverage across SE
Idaho. The models have been struggling with what to do with the
remains of the trough Thursday into Friday as a ridge builds across
the NE Pacific and today`s model cycle add`s yet another
potential solution and additional uncertainty. Huston

.AVIATION...Might see a thunderstorm or two develop along the Utah
border late this afternoon or evening. Otherwise VFR at the
terminals. Huston

.FIRE WEATHER...Critical fire weather conditions are anticipated
tomorrow afternoon/evening, prompting us to upgrade our fire weather
watch to a red flag warning. Widespread wind gusts 25 to 35 mph are
expected while humidity bottoms out around 10 to 15 percent.
Thunderstorms may linger just south of our border this evening, some
possibly crossing into Idaho. We`ll see cooler temperatures on
Sunday, with higher RH, so there should be a reprieve from the
critical fire weather conditions. High pressure will build back into
the area early next week as the heat returns. Next chance of any
showers and thunderstorms will be around mid-week in the Central
Mountains ahead of a mid-level disturbance. Hinsberger

Red Flag Warning from noon to 10 PM MDT Saturday for IDZ410-411-413-

Wind Advisory from 2 PM to 9 PM MDT Saturday for IDZ052.

Lake Wind Advisory from 2 PM to 9 PM MDT Saturday for IDZ054.

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