Damaging Winds in Idaho, April 5, 2024

Area Forecast Discussion
National Weather Service Pocatello ID
412 AM MDT Fri Apr 5 2024

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT...
A low pressure system will bring widespread rain showers, snow
showers, and isolated thunderstorms to all of southeast Idaho
starting later this AM, with showers increasingly mixing with or
changing to snow and continuing tonight, Sat, and Sat night as temps
cool. Highs in the 40s and 50s today will only reach the upper 30s
to mid-40s Sat. Forecast confidence in snow accumulations is very
low given their dependency on exact temps and snow
levels...generally a light coating is possible in most valleys and
plains, with 1 to 4 inches in the Island Park, Teton Valley, and
Caribou County regions as well as Galena Summit, increasing to 5 to
10 inches in most of our mntns above about 7000 feet. Overall,
accumulations generally fall below advisory criteria and/or remain
confined above pass level, but we'll continue to monitor closely as
slick areas of travel could certainly develop on some mntn highways
for periods of time over the next several days. Today will be breezy
out of the S-SW, but more westerly winds will increase late Sat AM
through Sat eve across the ern Magic Valley, Shoshone area, Raft
River region, and adjacent mntns to 25 to 35 MPH with gusts to 55
MPH. A WIND ADVISORY has been issued for these areas from 9 AM to 9
PM Sat. Use extra caution when driving, especially if operating a
high profile vehicle. This includes empty or lighter weight semi
trucks traveling on Interstate 84 and other local highways, as
strong highway crosswinds may be present in some spots. We recommend
securing outdoor objects before the winds increase Sat AM as well. 01

.LONG TERM...SUNDAY THROUGH NEXT FRIDAY...
Ensemble clusters in good agreement with progressive Omega
pattern over CONUS. Closed low ejecting into the Great Plains
states leaves room for secondary shortwave trough dropping through
PacNW Sunday, maintaining unsettled conditions over East Idaho.
System sags far enough south Monday into the Desert SW states
which allows beginnings of upper ridge to fold into the region.
Most of the rest of the week characterized by building ridge
through the intermountain west. Dry conditions are expected, with
temperatures rebound above normal by the latter half of the week.
DMH

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.AVIATION...
Complex mix of conditions is expected across East Idaho today.
Early morning IFR low stratus and fog impacting KBYI and KSUN.
With southwest winds in the valley, there is some expectation that
some of that moisture could still work toward at least KPIH
around sunrise. Otherwise, KPIH/KIDA/KDIJ should remain VFR.
Showers and tstorms begin pushing east, impacting all terminals
through the afternoon and evening. Ceilings drop to MVFR this
afternoon, and generally remain there through the overnight.
Temperatures turn much colder this evening, bringing a mix of
rain/snow to valley floors prior to 06Z. Any precipitation left
after 06Z should be all snow, with ceilings occasionally dropping
to IFR with isolated light snow showers. DMH

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.HYDROLOGY...
Spring flood season is upon us, and it's time to start keeping our
waterways in the back of our minds. While most of the major rivers
and creeks across southeast Idaho are expected to remain fairly
stable and solidly below action and flood stages during our next
several days of precipitation...we are forecasting the Portneuf
River in the Pocatello area to continue rising above minor flood
stage by this afternoon, before slowly falling back below minor
flood stage by early Sunday morning as precipitation coverage and
intensity starts to decrease and temperatures cool, helping to
stabilize melting and slow runoff. Minor flooding in the Sacajawea
Park area of Pocatello...and in fields near the confluence of the
Portneuf River and Marsh Creek in Inkom...are possible, and a FLOOD
ADVISORY has been issued. The Portneuf River further east (upriver)
toward Lava Hot Springs has also reached bankful conditions,
although it is not currently expected to reach minor flood stage
along this stretch. Elsewhere, expect noticeable rises on the Snake
River and Henrys Fork, but no flooding is currently expected on
these waterways over the next several days. REMEMBER...despite
recent warm air temps...the water in all of our rivers, creeks, and
streams largely originates from melting mountain snow and is
dangerously cold this time of year. Be especially careful to keep
children away from the water. - KSmith

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.PIH WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from 9 AM to 9 PM MDT Saturday for IDZ051-055>057.

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