Heavy Snow in Idaho, March 8 to 9, 2017

Name: Heavy Snow in Idaho, March 8 to 9, 2017
Start: 2017-03-08T17:00
End: 2017-03-09T08:00
Location: Idaho

March 8 to 9, 2017 · NWS MSO · 1 event in 1 county or zone

A plume of moisture moved over Idaho and western Montana causing heavy precipitation over central Idaho. Almost a foot of heavy wet snow fell in some areas.

Where it happened

Every event with a place to put it; 1 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

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Winter weather
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The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 1

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.

What happened

The episode as NWS MSO wrote it up.

A plume of moisture moved over Idaho and western Montana causing heavy precipitation over central Idaho. Almost a foot of heavy wet snow fell in some areas. The heavy snow and rain combined with already saturated soils to produce rock slides, fallen trees, and power outages. This led Clearwater County to declare a State of Emergency.

What forecasters said that day

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 Missoula, MT wrote its last area forecast discussion before the first event at Mar 8, 1:46 PM PST, 3 hours 14 minutes earlier.

Area forecast discussion, Mar 8, 1:46 PM PST, 3 hours 14 minutes before

Area Forecast Discussion
National Weather Service Missoula MT
246 PM MST Wed Mar 8 2017

.DISCUSSION...A plume of moisture continues to stream over north
central Idaho and west central Montana. The snow associated with
this moisture will increase in intensity later this evening and
cause significant snow fall in the higher terrain and some
impactful snow in the valleys of western Montana. Winter weather
advisories have been issued. Lookout, Lolo and Lost Trail will
experience the heaviest snowfall tonight with these locations
potentially getting up to a foot of new snow by mid morning.

The moisture feed shifts to northwest Montana on Thursday
afternoon and lingers there through Friday. This moisture will
interact with an arctic airmass coming over the divide. The
combination of arctic air with the moisture plume should cause
hefty snow amounts across northwest Montana. Locations north and
east of a line from Libby to Seeley Lake should receive 6 to 12
inches by Friday afternoon. Areas around Glacier Park could get
up to 18 inches with Marias pass potentially receiving 2 feet of
new snow. Uncertainty lies on how far into western Montana will
the arctic air intrude. The remainder of the Northern Rockies
appear to receive a rain/snow mix as the area will be in the warm
sector of this disturbance. The higher terrain north central Idaho
and west central Montana should still receive an impactful amount
of snow by Friday. Winter Storm Watches have been issued for the
areas that have the best chance of being impacted by this storm.

Saturday will be a very nice day in comparison to the past week
with plenty of sun early on with normal temperatures all the way
into the mid and upper 40s. This will be short lived as yet
another wet weather disturbances enters the region.

Under a northwest flow and supported by a strong jet stream plenty
of moisture will move through the region, especially in north
central Idaho and much of western Montana. Probably the biggest
difference with this system is it will be a tad bit higher with
snow levels around 4000-5000 feet south of the I-90 corridor and
3000-4000 feet north of I-90. The fast moving system will limit
snow amounts. 1-2" of snow is likely in the valleys of the
Flathead Valley northward and into the Glacier NP region including
Essex and Columbia Falls. Otherwise valley precipitation will be
mostly rain in the lower valleys. Lookout and Marias pass can
expect 2-5" of snow

Sunday and Monday: Unstable and continued moist air will produce
scattered rain and mountain snow showers each day.

A ridge builds over the region by early to mid week bringing
warmer temperatures and mainly dry conditions to the region.
Temperatures might actually reach the 50 degree mark in some
valley locations. There will be some scattered light showers in
the mountains. Northwest Montana valleys may experience some
local flooding issue with the melting snow especially as
temperatures may stay above freezing.

&&

.AVIATION...Rain/snow showers will continue to impact area
terminal KMSO and KBTM through Thursday morning. Snow levels will
lower slightly tonight and will allow for the showers to
transition to all snow. KGPI and KSMN will see mainly breezy
conditions through this afternoon with chances of snow increasing
at around 09/0600Z. Main impacts with the snow tonight will be
reduced visibilities and lowered ceilings. Showers will be on the
decrease Thursday morning, but another weather system will bring
in more precipitation Thursday afternoon and evening.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory from 6 PM this evening to 10 AM MST
     Thursday Bitterroot/Sapphire Mountains...Lower Clark Fork
     Region.

     Winter Weather Advisory from 8 PM this evening to 9 AM MST
     Thursday Butte/Blackfoot Region...Potomac/Seeley Lake
     Region.

     Winter Weather Advisory from 8 PM this evening to 9 AM MST
     Thursday Flathead/Mission Valleys...Missoula/Bitterroot
     Valleys.

     Winter Storm Watch from Thursday afternoon through Friday
     morning Flathead/Mission Valleys...West Glacier Region.

     Winter Weather Advisory from 8 PM this evening to 9 AM MST
     Thursday Kootenai/Cabinet Region...West Glacier Region.

     Winter Storm Watch from Thursday afternoon through Friday
     morning Kootenai/Cabinet Region.

ID...Winter Weather Advisory from 6 PM MST /5 PM PST/ this evening to
     10 AM MST /9 AM PST/ Thursday Eastern Lemhi County...
     Northern Clearwater Mountains...Southern Clearwater
     Mountains...Western Lemhi County.

&&

In the hours before

Local storm report, Mar 8, 11:01 AM PST, 5 hours 59 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
1201 PM MST WED MAR 8 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1200 PM     SNOW             7 SSE CONDON            47.44N 113.65W
03/08/2017  M3.3 INCH        MISSOULA           MT   TRAINED SPOTTER

            .

&&

NWS MISSOULA MT
IRIS SYSTEM

Local storm report, Mar 8, 11:04 AM PST, 5 hours 56 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
1204 PM MST WED MAR 8 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1204 PM     SNOW             POTOMAC                 46.89N 113.57W
03/08/2017  E3.0 INCH        MISSOULA           MT   TRAINED SPOTTER

            .

&&

NWS MISSOULA MT
IRIS SYSTEM

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

1 heavy snow. Local standard time, as filed.

Heavy Snow, Orofino / Grangeville Region

When: March 8, 5:00 PM PST to March 9, 8:00 AM PST
Where: Orofino / Grangeville Region forecast zone
Reported by: Department of Highways
Coordinates: 46.259, -115.562 (the zone’s center; the record gives no point)

Heavy wet snow contributed to multiple rock slides with one covering Mount Idaho Grade Road southeast of Grangeville. Due to the already saturated ground, the heavy precipitation downed multiple trees and power lines. Widespread power outages were reported with one spotter reporting 8.5 hours without power east of Kooskia. Snowfall amounts ranged from 4 inches in Grangeville to up to 10 inches across the northern Camas Prairie. Mud slides, washed-out culverts and streams that were bankful contributed to Clearwater County declaring a State of Emergency on the 10th.

What these are

Heavy Snow: Snowfall reaching the local warning threshold without the other hazards of a winter storm.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Idaho in 2017 Every state in 2017 This day in weather history Warnings in Idaho, March 2017

Sources

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: 678355.