405
FXUS65 KPIH 302000
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
200 PM MDT Sun Jun 30 2024

.SHORT TERM...Tonight through Monday Night.
Early afternoon satellite imagery shows a cold front passing over
CNTRL Idaho and WRN Montana of which will continue to track east
heading into tonight. Isolated showers/thunderstorms and an uptick
in winds will be the primary impacts associated with this front
with a MARGINAL RISK (5-14% chance) for severe thunderstorms from
the Storm Prediction Center along the Idaho/Montana border for
Lemhi, Clark, and Fremont Counties. Aided by around 200-600 J/kg
of SBCAPE and 25-35 kts of 0-6 km shear, we may see some isolated
stronger storms which could produce wind gusts in excess of 40
mph and small hail. The HREF model probability of thunder through
6 AM Monday shows a 10-20% chance across our CWA outside of a
30-60% chance further north along the Montana border region. Given
PWATs around that 0.50-0.80" range both today and Monday, we also
may see a mix of wet and dry thunderstorms given a drier
environment in place.

Showers and thunderstorms will continue into Monday as synoptic
winds see a slight increase versus today. As a result, a LAKE WIND
ADVISORY is now in effect for American Falls Reservoir for Monday
with winds staying just below criteria today. The HREF model
probability of thunder will also increase for Monday to a 40-80%
chance across the Upper Snake River Plain, ERN CNTRL Mountains,
and ERN Highlands with a 20-40% chance elsewhere. Stronger storms
will again be capable of producing gusty winds and small hail.
Drier conditions will then return regionwide Monday night into
Tuesday outside of isolated showers across the ERN Highlands as a
drier air mass settles back in for midweek. High temperatures
today in the mid 70s to low 90s will decrease for Tuesday by
around 6-12 degrees behind today`s cold front. Total rainfall
accumulations through Tuesday will remain on the lighter side with
the bulk of our CWA staying dry or seeing less than 0.10" of rain.
Higher amounts are expected however across NE Idaho along the
Montana and Wyoming borders where around 0.10-0.30" of rain is
expected with locally higher totals. MacKay

.LONG TERM...Tuesday through next Sunday.
By Tuesday, our weather pattern will be shifting with only a 20
percent chance of a lingering shower or storm up near the Island
Park area while the rest of eastern Idaho dries out and begins to
warm up. As we remain in northwest flow aloft, highs will
generally be in the 70s to near 80 degrees on Tuesday before
returning to the low to mid 80s for Wednesday, Thursday, and
Friday. Temperatures will drop just a couple of degrees on
Thursday from the mid 80s on Wednesday and Friday as a low passes
to our east. Again, we will be keeping an eye on this system as
it`s not expected to bring much for impacts to us based on its
current track, but any deviated farther west or south could
introduce some PoPs in the Eastern Highlands greater than our
current 20 percent chance in the Island Park area. While it still
looks like we will be heating up even more through next weekend,
the GFS has started to stray from the ECMWF in its location of the
high pressure ridge. The ECMWF still builds in the heat dome
almost right on top of Nevada and the GFS holds it just off of the
West Coast now. We will have to see if this westward trend
continues, but either way NBM probabilities give a 50 to 60
percent chance of the eastern Magic Valley and lower Snake Plain
returning to the 90s by Sunday. AMM

&&

.AVIATION...For the 18Z TAFS through 18Z Monday.
Predominant VFR and mostly dry conditions will continue into
Monday under partly to mostly cloudy skies as a cold front tracks
east across SRN Idaho. Winds will peak this afternoon around 10-20
kts with gusts to 20-30 kts as isolated showers and thunderstorms
continue to build in out of the west. The HREF model probability
of thunder starting this afternoon through 12Z Monday shows a
10-20% chance of thunderstorms at all terminals with those chances
increasing for 12Z Monday through 12Z Tuesday to a 20-30% chance
at KPIH, KBYI, and KSUN with KIDA and KDIJ increasing to a 50-70%
chance. The primary hazard with stronger storms both days will
center around outflow wind gusts to around 30-40 kts. MacKay

&&

.FIRE WEATHER...
A cold front is working its way through Idaho today and will
bring showers and thunderstorms along with it. The best chance for
these storms will be up in the Central Mountains and upper Snake
Plain into the Island Park area where there is a 20 to 40 percent
chance. Activity will pick up in the Southern Hills and the rest
of the Snake Plain this evening through the overnight hours. The
24-hour probably of a wetting rain remains at about a 30 to 50
percent chance in the northern portion of Zones 475 and 476,
particularly in Lemhi county. It increases to a 50 to 70 percent
chance in the portion of Zone 410 north of a line from Dubois to
Ashton and throughout 411. Any storms in the eastern Magic Valley
and Snake Plain are expected to be dry storm, since there is only
a 10 to 30 percent chance of a hundredth of an inch over the next
24 hours. This system will at least help increase min RHs just a
bit with most in the upper teens to mid 20s on Monday. Of course,
RHs will be higher in the Eastern Highlands where precipitation
chances are higher. Winds will be gusty on Monday, especially in
Zone 425 with gusts up to 40 mph. It will be breezy throughout
Zones 410, 413, and 427, too, with gusts in the 25 to 35 mph.
Tuesday will be a bit breezy, but gusts will be closer to 20 to 25
mph throughout the eastern Magic Valley and Snake Plain.
Wednesday will be quite dry with RHs mostly in the teens and we
will also see gusts of 30 to 40 mph across much of eastern Idaho.
AMM

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Lake Wind Advisory from 12 PM to 9 PM MDT Monday for IDZ054.

&&

$$