FXUS65 KBOI 060303

Area Forecast Discussion
National Weather Service Boise ID
903 PM MDT Fri Jun 5 2020

.DISCUSSION...Strong storms noted across Baker County earlier this
evening have started to weaken. Meanwhile, strong wind related to
outflow from these storms is continuing to advance through the
Treasure Valley. Wind impacts will linger resulting in some
limited visibility in dust. These conditions will move east
through the night. No changes planned to immediate term forecast
as focus remains on short-fused weather products. However,
forecast looks on track with strong system impacting the are
through the weekend resulting in showers and cooler temperatures.


.AVIATION...VFR. Scattered showers developing tonight across the
region. A gust front will move through the Treasure Valley around
03z at EUL BOI with gusts up to 45kt and blowing dust. Surface
winds: NW 30-40kt along the gust front and behind it for a few
hours, especially near ONO EUL BOI MUO, and generally NW 10-20kt
overnight. Winds aloft to 10k feet MSL, southwest 15-20kts.

Weekend Outlook...Intermittent showers expected Saturday and
isolated thunderstorms during the afternoon. Gusty erratic winds
up to 45kt possible near thunderstorms during the afternoon.
Widespread mountain obscuration and MVFR/IFR conditions developing
by Saturday night lasting into Sunday. Snow levels drop to
5000-7000 feet MSL by Sunday with widespread precipitation and
continued flight restrictions.


SHORT TERM...Tonight through Sunday night...Strong storms are
possible this afternoon and evening, especially in eastern Oregon
north of Rome and in Idaho north of a line from Caldwell to Idaho
City to Stanley. Strong shear, along with ample heat and
moisture, will create conditions favorable for storms to bring
wind gusts greater than 50 mph and also hail to around 1 inch in
diameter. A cold front will move through the region this evening
and overnight, bringing a separate threat for winds gusting 30 to
40 mph. The front, or more likely a combination of storm outflow
and the front, will move through Baker City around 6 pm PDT,
Ontario around 8 pm MDT, Caldwell around 9 pm MDT, the greater
Boise area between 9 and 10 pm MDT, Mountain Home shortly after 10
pm, and through the Hammett and Glenns Ferry areas by 11 pm
before weakening as it heads through the western Magic Valley
around midnight.

As the large upper level low that is dominating our weather over
the next few days moves closer tonight and Saturday, and then
through the area Sunday, we will see multiple periods of showers
and storms and much cooler weather. After highs today in the 90s
in the lower elevations, we will see 60s Saturday and 50s Sunday.
Snow levels will come down beginning tomorrow, and reach 5000-5500
ft Sunday morning, before rising again Sunday night. This will
allow 3 to 4 inches of snow to accumulate on the ski areas, and up
to 10 inches on the highest peaks of Adams and Valley counties.
Rainfall amounts through 6 am Monday morning will average 0.2 to
0.7 inches in lower elevations and 1.0 to 1.75 inches in the
mountains. This is an unseasonably strong storm for June, and is
more typical of an early spring system.

LONG TERM...Monday through Friday...The low pressure system is
exiting our region Monday leaving lingering showers for our higher
elevations. A warm front pushes through Tuesday morning helping
get temperatures climbing back above normal once again.
Precipitation returns with this boundary for our northern tiers
Tuesday afternoon before a brief break. By the end of the period
another upper low can be seen drifting south, but differences in
tracking are evident among models. Left the mention of showers
returning Friday in the forecast for now and will evaluate further
with new model runs.






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