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471
FXUS65 KPIH 202003
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
203 PM MDT Mon May 20 2024

.SHORT TERM...
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Tonight and Tuesday
Afternoon satellite imagery continues to show an upper trough
digging across the region this afternoon. Seeing increasing cloud
cover and showers across the central mountains and into the Arco
Desert and hi-res CAMs show these continuing to push southward over
the remainder of the day and into the evening. Precipitation will be
showery in nature though so not everyone will get in on the action.
Cooler temps and cloud cover will keep snow levels around 6500-7000
ft so any elevations above that level will see some snow showers.
Valley temps are only in the 50s this afternoon and another
seasonably cool night is expected. A frost advisory is in place
once again across the growing region and a few rural spots could
certainly drop below freezing but this isn`t expected to be
widespread.

Tomorrow we`ll continue to feel the influence of the trough with
another round of showers and storms possible. PoPs tomorrow
generally favor the eastern highlands though as the trough continues
to move east of the area with very weak riding across western
portions of the forecast area. With less cloud cover, daytime highs
should be able to get closer to 60 for the lower terrain while
remaining in the 50s across the high country. A more impactful
system looks to move into the region for mid-week however. McKaughan

.LONG TERM...Wednesday through Memorial Day
Our next low will impact central and eastern Idaho midweek. There
are some subtle differences which could impact a more southern
push of better moisture, but the consensus right now is that the
central mountains and eastern highlands will see the most rain or
snow at the moment. Early snowfall totals have 6" or less between
6000-9000ft, with locally higher numbers on the highest peaks and
ridges. Probability forecasts also support amounts above 6"
(55-85%) for places like Borah, and along the Montana border.
Temperatures support at least seeing some snowflakes down to
around 4500-5000ft Thursday morning, but accumulations appear slim
to none right now. If we can get a heavy band or showers to
develop, we could see something brief stick to non-road surfaces.
It will be breezy on Wednesday, although it appears we are falling
below any wind-related thresholds. Heading to the Memorial Day
weekend, look for some mountain showers Friday...with an
increasing chance of precipitation Saturday and Sunday. Memorial
Day itself MAY be dry. Our Blend of Models only has a few showers
over the eastern and southeast highlands, as high pressure builds
just to our west. That fits with about 75% of the cluster
forecasts. Keyes
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.AVIATION...
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We continue to watch a round of showers and isolated storms
through this evening. The overall forecast should remain VFR with
short drops below that with any heavier activity moving over a
particular airport. We are carrying VCSH at all sites except DIJ
and SUN. We left DIJ as -SHRA from before, and adjusted SUN to
-SHRA VCTS. We should see everything diminish between midnight and
sunrise. Keyes
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.HYDROLOGY...
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Elevated river levels continue on the Portneuf River at Pocatello
and Topaz. River levels are expected to gradually recede over the
upcoming week but will likely remain high enough to warrant
continued flood products for much of the week. McKaughan
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.PIH WATCHES/WARNINGS/ADVISORIES...
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Frost Advisory from 3 AM to 9 AM MDT Tuesday for IDZ051>055.
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$$