Moist warm air moving over the Northern Rockies brought heavy snow and freezing rain to parts of central Idaho. Multiple snow slides were reported in Lemhi county during this event.
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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 MSO wrote it up.
Moist warm air moving over the Northern Rockies brought heavy snow and freezing rain to parts of central Idaho. Multiple snow slides were reported in Lemhi county during this event.
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 Feb 3, 1:43 PM PST, 3 hours 17 minutes earlier.
Area Forecast Discussion
National Weather Service Missoula MT
243 PM MST Fri Feb 3 2017
...PROLONGED SNOW ACROSS NORTHERN ROCKIES THROUGH MONDAY...
.DISCUSSION...The first pulse of moisture and energy is making its
way across the Northern Rockies today causing widespread snow with
periods of moderate snowfall rates. This southwesterly upper
level flow will persist over the Northern Rockies with fairly
steady precipitation falling in the higher terrain, especially
from Clearwater County up into northwest Montana. Several more
weak disturbances will make its way across the region through the
weekend with the most intense one being Sunday afternoon and
night. Winter weather advisories have been issued for most of the
Northern Rockies today through Sunday morning, then a Winter Storm
Watch for the potential period of heavier snowfall.
This southwesterly flow will allow a warmer airmass to be ushered
into the region allowing most of the valleys of north central
Idaho and west central Montana to mix out the cold air. During the
process of warmer air making it to valley bottom, the
precipitation will change from snow to potentially freezing rain
and finally rain. These pockets of freezing rain could create
slick road conditions. Another concern for the warm up in the
valleys, especially around Grangeville/Orofino and the Bitterroot
Valley, will be the snow melt causing urban water issues.
Northwest Montana does not appear to have enough warm air for this
transition so the precipitation type will likely remain all snow.
A cold front makes its way across the Northern Rockies on Monday
causing snow levels to drop to most valley bottoms. Precipitation
will be enhanced along the leading edge of the front on Monday.
The exact timing of the front is still uncertain.
Snow showers will linger across the Northern Rockies during
Tuesday. However, accumulations will be much less noteworthy than
the previous snow event. Temperatures will remain fairly wintry,
though not bitterly cold.
A major warming pattern change is anticipated to take place
across the Northern Rockies Wednesday through Friday. On
Wednesday, high pressure will surge across the Northern Rockies
from the south, accompanied by a minor surge of moisture.
Precipitation across the region will begin mainly as light snow,
however as the air aloft warms, the pattern changes to favor snow
changing to freezing rain in many area valleys. The freezing rain
impact will be most significant for high and mid elevations
valleys, where temperatures have been below freezing for much of
the past couple months. Hazardous travel conditions with slippery
roads will be present during this warming transition. A secondary
effect of the rapid warming across the region will also allow low
elevation snow to melt at a fast rate. Considering the relatively
deep low elevation snow pack near population centers, the melt-off
will lead to ponding of water near buildings and across low lying
roadways. Basement flooding from the melt-off is also possible,
whether over the ground or percolation through the frost layer in
the ground. This scenario appears similar to the rapid low
elevation melting that occurred toward the end of winter 2014.
Conditions are anticipated to cool once again by next weekend,
however not anything as cold as most of December and January.
Expect low elevation snow pack to continuing melting and creating
ponding and flooding issues through mid February.
&&
.AVIATION...Southwesterly flow will persist over the Northern
Rockies through the weekend causing widespread precipitation. Weak
disturbances will be making its way through this flow which will
enhance the snowfall rates. KGPI and KMSO will have the biggest
impact for lowered visibilities and ceilings during the snowfall
enhancement. In addition, KMSO could experience periods of
freezing rain by Friday night.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory until 11 AM MST Sunday
Bitterroot/Sapphire Mountains.
Winter Weather Advisory until 11 AM MST Sunday Lower Clark Fork
Region.
Winter Storm Watch from Sunday morning through Monday afternoon
Lower Clark Fork Region.
Winter Weather Advisory until 11 AM MST Sunday Flathead/Mission
Valleys...Kootenai/Cabinet Region...West Glacier Region.
Winter Storm Watch from Sunday morning through Monday afternoon
Flathead/Mission Valleys...Kootenai/Cabinet Region...West
Glacier Region.
Winter Weather Advisory until 11 AM MST Sunday Potomac/Seeley
Lake Region.
Winter Storm Watch from Sunday morning through Monday afternoon
Potomac/Seeley Lake Region.
Winter Weather Advisory until 11 AM MST Saturday
Missoula/Bitterroot Valleys.
ID...Winter Weather Advisory until 10 AM PST Sunday Northern
Clearwater Mountains...Southern Clearwater Mountains.
Winter Weather Advisory until 11 AM MST Saturday Eastern Lemhi
County...Western Lemhi County.
Winter Weather Advisory until 10 AM PST Saturday
Orofino/Grangeville Region.
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
521 PM MST FRI FEB 3 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0520 PM SNOW 2 WSW COLUMBIA FALLS 48.37N 114.21W
02/03/2017 M4.0 INCH FLATHEAD MT TRAINED SPOTTER
. THE DURATION OF THE SNOW EVENT WAS 2 HOURS
30 MINUTES.
&&
NWS MISSOULA MT
IRIS SYSTEMPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
523 PM MST FRI FEB 3 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0430 PM SNOW 1 SW COLUMBIA FALLS 48.36N 114.20W
02/03/2017 M5.0 INCH FLATHEAD MT TRAINED SPOTTER
.
&&
NWS MISSOULA MT
IRIS SYSTEMThe national radar mosaic for the moment the first event began.
2 winter weather, 1 avalanche. Local standard time, as filed.
The Idaho Transportation Department reported widespread ice on Hwy 14 leading to Elk City, ID. At higher elevations, heavy snow fell, with the public reporting 15 inches of snow at Lolo Pass.
The Clearwater County Emergency Manager reported rain freezing on already frozen back roads, leading to additional glazing overnight. This caused cars to have difficulty in gaining traction, especially on driveways. Even vehicles with chained tires had difficulty navigating during the event.
Warm weather and rain helped prime conditions for multiple snow slides that covered roads in Lemhi county. The Idaho Transportation Department reported one 100 ft wide and 10 ft high snow slide on Hwy 93 north of Salmon, ID that completely blocked the road for 1.5 hours. Four other smaller slides caused roads to be reduced to one lane, and heavy equipment was needed to clear snow.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Idaho in 2017Every state in 2017This day in weather historyWarnings in Idaho, February 2017
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: 680277, 680276, 680278.