A low pressure system brought wraparound snow showers to the Boise Mountains and the Upper Treasure Valley, bringing heavy, wet, snow to many cities. This cause road delays and fallen trees on major thoroughfares in the mountains.
Every event with a place to put it; 2 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS BOI wrote it up.
A low pressure system brought wraparound snow showers to the Boise Mountains and the Upper Treasure Valley, bringing heavy, wet, snow to many cities. This cause road delays and fallen trees on major thoroughfares in the mountains.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Boise, ID wrote its last area forecast discussion before the first event at Apr 5, 7:52 PM MST, 4 hours 8 minutes earlier.
Area Forecast Discussion...Updated
National Weather Service Boise ID
852 PM MDT Fri Apr 5 2024
.DISCUSSION... (Update: Snow has begun to accumulate on
roads in Boise and points east, and forecast has been updated
for up to two inches accumulation there overnight, along with
slushy and locally snow-covered roads.)
Rain and snow continue in our CWA this evening as upper low center
moves eastward across Owyhee County. Low should move to southeast
Idaho Saturday morning, then across the Continental Divide in WY
and CO midday Saturday. Heaviest pcpn has collected on the low's
northern and western flanks and should continue in Idaho zones most
of the night, ending as snow showers from the west Saturday morning.
A Winter Weather Advisory in Idaho south of the Snake Basin will
remain in effect until its current expiration time of 9 AM MDT
Saturday, but will end in Malheur County at 3 AM MDT Saturday.
Rain has mixed with snow at Boise this evening and should
become all (wet) snow by midnight, accumulating up to a half
inch overnight on grassy areas. Roads will stay wet. Wet snow
may accumulate up to an inch in the western Magic Valley but
roads should stay wet there, too. Current PoPs could be
increased 10-15 percent but an update wouldn't accomplish much
in terms of impact. As the upper low exits east Saturday
westerly surface winds will increase to advisory speeds in the
central Snake Basin and Camas Prairie. Will continue a Wind
Advisory for all of south-central Idaho from 9 AM MDT to 9 PM
MDT Saturday, unchanged from this afternoon.
&&
.AVIATION...MVFR/IFR and localized LIFR conditions in numerous
showers for far E Oregon into southwest Idaho. Showers becoming
scattered after Sat/16Z. Mountains obscured. Snow levels at/near
valley floors. Patchy morning fog and low stratus. Surface winds:
W-NW 5-15 kt. Winds becoming 15-25 kt with gusts to 30-40 kt at
KMUO/KJER/TWF after Sat/12Z. Winds aloft at 10k ft MSL: W-NW
20-30 kt.
KBOI...Persistent rain/snow mix through Sat/08Z, then periods
of snow showers continuing through Sat/16Z. MVFR/IFR from
precipitation and low ceilings. Little to no snow accumulations,
with temperatures remaining at or slightly above freezing
through Sat morning. Flight category should start to gradually
improve after Sat/08Z. Surface winds: W-NW 5-15 kt.
Sunday Outlook...Patchy morning fog and low stratus. Scattered
rain/snow showers. Sunday snow levels are now expected to be lower,
at 3500-4500 ft MSL. MVFR/IFR and mountain obscuration in showers.
Winds W-NW 5-15 kt, except W-NW 15-25 kt with gusts to 25-35 kt for
KMUO/KJER/KTWF.
&&
.HYDROLOGY...Rain and snow through early Sunday. Small streams
and creeks will continue to run high, but minor street flooding
and ponding in low-lying areas will slowly decrease. The Owyhee
River has reached moderate flood stage and is forecast to
continue there until Wednesday.
&&
.PREV DISCUSSION...
SHORT TERM...Tonight through Sunday night...The low pressure
system is hanging out just south of the Idaho-Nevada border,
with wrap-around precipitation bands bringing steady wet snow
and rain to much of the region. Harney County and Baker County,
OR have remained mostly dry through the day, but more
precipitation is on the way as the low moves to the northeast.
The heaviest precipitation and snow will be over higher terrain.
Colder air will move into the region tonight, with most
precipitation shifting over to snow by early morning Saturday.
Accumulations below 4000 feet in the Treasure Valley will be
light, with less than a half of an inch anticipated. Any
accumulation will likely be over grass, with roads staying wet.
Therefore, any minor travel impacts will be confined to
locations above 6000 feet north and east of the Treasure
Valley. Lingering snow will fall southwest of the Treasure
Valley in Malheur County, OR and the Owyhee Mountains/Southwest
Highlands. Winter weather advisories will remain in place for an
additional 2-4 inches of snow that will impact travel overnight
and tomorrow morning. Elevations above 6500-7000 feet will see
the most snow, with nearly a foot anticipated over Bogus Basin
and ridgetops in the Boise Mountains/Owyhee Mountains. Light
snow and valley rain will linger over the West Central and Boise
Mountains as the low moves east. Snow levels will be around
3500-4500 feet during the day and near valley floors overnight
today and Saturday, but will elevate to 5000-6000 feet on
Sunday.
Gusty afternoon westerly winds still look to increase over
south central portions of Idaho over the Magic Valley and Camas
Prairie tomorrow as northwesterly flow aloft takes over and the
gradient wind increases. Sustained winds 20-30 mph will
accompany gusts to 40-50 mph. Therefore, the wind advisory will
remain in place for tomorrow.
Temperatures will remain 5 to 10 degrees below normal through
the short term period, although a warming trend will begin late
Sunday as a ridge begins to move into the region.
LONG TERM...Monday through Friday...An upper level ridge will
build in over the region, with temperatures anticipated to be
above normal. Temperatures in the lower elevation valleys near
the end of the long term will approach 80F, with a 40-50%
chance of reaching 80F in Boise on Thursday and a 60-70% chance
of reaching it on Friday. Dry and clear conditions will persist
through the long term period, with breezy afternoon westerly
winds until Thursday with a shift to easterly winds.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Winter Weather Advisory until noon MDT Saturday IDZ015-029.
Wind Advisory from 9 AM to 9 PM MDT Saturday IDZ016-028-030.
OR...Winter Weather Advisory until 3 AM MDT /2 AM PDT/ Saturday
ORZ063.
&&
www.weather.gov/Boise
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DISCUSSION...LC
AVIATION.....SA
HYDROLOGY....LC
SHORT TERM...SA
LONG TERM....SAThe national radar mosaic for the moment the first event began.
1 heavy snow, 1 winter weather. Local standard time, as filed.
Several members of the public reported 12 inches of wet snow up at the Bogus Basin Ski Resort, along with fallen trees that blocked roads up to Bogus Basin and on Highway 21 near Idaho City. Spotters in Idaho City measured 6.0 inches of snow.
A member of the public measured 3.0 inches of snow just north of the Boise downtown.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Idaho in 2024Every state in 2024This day in weather historyWarnings in Idaho, April 2024
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1173815, 1173816.