Area Forecast Discussion
Issued by NWS Pocatello, ID

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000
FXUS65 KPIH 251951
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
151 PM MDT Sat Jun 25 2022

.SHORT TERM...Tonight through Sunday.

High pressure will produce dry weather through the remainder of the
weekend. Northeast breezes today are strong enough to justify a lake
wind advisory for the American Falls Reservoir. Looking at a
combination of NBM guidance, HRRR, and 3km NAM, expect winds to
diminish some but winds may remain a little too close to advisory
criteria to comfortably allow the product to expire at 22z. So will
continue the advisory into the evening. So will extend the advisory
through 03z. Winds look light on Sunday and temperature rebound with
many areas seeing highs in the upper 80s to near 90. Most locations
across the Snake Plain and eastern Magic Valley have a 20-30% chance
of seeing highs exceed 90 on Sunday.

13

.LONG TERM...Monday through next Saturday. High pressure remains in
control early next week, with the upper ridge axis expected to pass
through Monday/Monday night. The warming trend will continue in
response, with lower elevations expected to reach the upper 80s to
mid 90s for highs. Primarily dry conditions are expected to persist
on Monday, but can`t rule out a couple of isolated
showers/thunderstorms during the afternoon/evening over the higher
terrain as limited mid-level moisture advects into the area from the
west/southwest. This along with strong diurnal heating/weak
instability may be sufficient to trigger a stray high-based shower
or storm or two producing little rain. By Tuesday, the upper ridge
begins to propagate east, giving way to strengthening west/southwest
flow ahead of an upper low over the WA/BC coast. Winds will be on
the increase in the tightening gradient, and Tuesday/Wednesday look
to be the windiest days of the week. Seeing some muted signals in
the ECMWF Extreme Forecast Index (EFI) data these days, and have
nudged forecast winds toward the stronger NBM v4.1 data which
generally performs better on the windier days. Tuesday is expected
to be the warmest day of the week as lower elevations climb into the
90s. NBM v4.1 probabilities of reaching 90F or higher are greater
than 75% through much of the Lower Snake Plain, Eastern Magic
Valley, and southern valleys toward the UT border, giving high
confidence in the warm temps. Chances of reaching 100F drop off
markedly (generally 5% or less except in the Eastern Magic Valley
where they peak near 20%), so it doesn`t look like we`ll see the
first triple digits of the year just yet. With the warm temps Monday
and Tuesday, we are seeing a moderate risk in the Heat Risk for
those sensitive to heat, but temperatures look to cool off
sufficiently overnight to preclude a higher threat to the general
population. We do see a little better chance for showers and
thunderstorms on Tuesday with better moisture advection and forcing
ahead of the aforementioned low, mainly favoring the Eastern
Highlands. Still chances look limited overall. Temperatures cool 7-
10 degrees Wednesday in wake of a weak cold front, but winds remain
elevated as mentioned. May see a lingering chance for an isolated
storm in the Eastern Highlands, but the large majority of the area
will remain void of any rain chances. Late week into next weekend,
temperatures gradually warm under westerly flow/low-amplitude
ridging. There are hints that some monsoon moisture may be able to
work north into eastern ID next weekend, possibly bringing the next
chance for showers/thunderstorms. KB

&&

.AVIATION...VFR conditions will persist through the period as high
pressure aloft gradually builds over the region, resulting in
predominantly clear skies with perhaps a few high clouds tonight
into Sunday. Northeast winds down the Snake Plain will remain a
little breezy this afternoon, gusting to around 20 KTS at KPIH,
KIDA, and KBYI before quickly dissipating to less than 10 KTS early
this evening. Expect lighter winds with typical diurnal trends at
KSUN and KDIJ. KB

&&

.FIRE WEATHER...High pressure will produce dry weather across most
of the area through Sunday. Dry thunderstorms will bubble up from
Nevada on Sunday afternoon and may get close to Idaho fire zone 427
late Sunday afternoon or evening. Afternoon humidities will run in
the teens to low 20s Sunday and Monday. We could see isolated dry
thunder across the mountains and highlands on Monday as a weak push
of moisture slides into the region.

13

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Lake Wind Advisory until 9 PM MDT this evening for IDZ054.

&&

$$


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