A cold front associated with a strong Pacific storm system brought significant snowfall amounts to much of eastern Utah, including many lower elevation locations which experienced their first significant snowfall of the season.
Every event with a place to put it; 4 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 GJT wrote it up.
A cold front associated with a strong Pacific storm system brought significant snowfall amounts to much of eastern Utah, including many lower elevation locations which experienced their first significant snowfall of the season.
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 Grand Junction, CO wrote its last area forecast discussion before the first event at Dec 20, 5:02 PM MST, 3 hours 58 minutes earlier.
Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
502 PM MST Wed Dec 20 2017
.SHORT TERM...(Tonight through Thursday night)
Issued at 253 PM MST Wed Dec 20 2017
The approaching storm has modified a bit on satellite and in
forecast models. Satellite shows it moving a bit slower than over
the last 24 hours and the models picked up of this and drag the
main guts of the system through central CO and UT more slowly
Thursday morning. The models have also weakened the system
somewhat, especially Thursday afternoon through the evening. It
should produce a bit less precipitation, but this will have only
minor affects on the hazards currently in effect.
Generally the hazards should end about 6 hours earlier and the
winter weather advisories were cancelled for the Paradox Valley,
the Central Gunnision and Uncompahgre basin (including Montrose),
and the Upper Gunnison basin (including Gunnison). In those areas
the precipitation will start later, thus temperatures will be
warmer and by the time the front arrives in south-central CO it
will be weaker.
Advisories in the other areas will continue with lessor amounts of
snow expected. Considering this is the first significant and
widespread winter weather in some time and the bulk of the
precipitation will fall during the morning commute and for a few
hours thereafter, impacts to travel should be significant. This
timing should justify continuing the advisories even if the total
snow accumulations fall just short of strict advisory criteria.
Conditions should improve quickly from NW to SE Thursday afternoon
and night.
.LONG TERM...(Friday through Wednesday)
Issued at 253 PM MST Wed Dec 20 2017
No change in the first few days of the long term. Friday should be
mostly dry, with probably only a few remnant showers near the
Continental Divide. The cold advection will begin and continue in
earnest Saturday as an arctic trough moves through much of the
area. This should reinforce the cold air and provide a second shot
of moisture and snowfall for especially areas north of the
Continental Divide. The mountains above Steamboat Springs and Vail
Pass stand the best chance for snowfall and should see the
coldest temperatures as well.
Sunday through Monday will see the forecast area under mainly
zonal flow with and old boundary along the northern border area.
Then Tuesday the situation begins to change again. A strong
Pacific trough is projected to dig into the Pacific Northwest.
Winds aloft will begin to strengthen and shift to the southwest.
By Wednesday the GFS has this low closed off over southern Idaho
with strong SW flow over the forecast area. Its cold front and
precipitation ought to affect Eastern UT and portions of western
CO by Wed. afternoon.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 502 PM MST Wed Dec 20 2017
VFR conditions are presently in place with mid and high clouds
passing by ahead of an approaching cold front. Likely some gusty
ridge top winds and associated turbulence with lenticular clouds
seen on latest satellite imagery and out the door. Expect
deteriorating conditions starting in NE Utah late this evening
near the cold front. This front and snowfall will be spreading
south and east through the area overnight into Thursday morning.
Near the front MVFR is highly probably with IFR at least possible
for a few hours in many places. Behind the front MVFR may linger
into the afternoon hours in some locations with cigs below ILS
markers in many areas. Terrain obscuration will be widespread and
strong mountain top winds should continue to produce localized
areas of turbulence. Improvement comes late.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Winter Weather Advisory from 9 PM this evening to 6 PM MST
Thursday for COZ003>005.
Winter Weather Advisory from midnight tonight to 6 PM MST
Thursday for COZ001-002-006>008.
Winter Weather Advisory from 9 PM this evening to midnight MST
Thursday night for COZ010-012.
Winter Weather Advisory from 2 AM Thursday to midnight MST
Thursday night for COZ018-019.
Winter Weather Advisory from 9 PM this evening to 9 PM MST
Thursday for COZ009-013-017.
UT...Winter Weather Advisory from 9 PM this evening to 6 PM MST
Thursday for UTZ025.
Winter Weather Advisory from midnight tonight to noon MST
Thursday for UTZ024.
Winter Weather Advisory from midnight tonight to 6 PM MST
Thursday for UTZ027-029.
Winter Weather Advisory until noon MST Thursday for UTZ023.
Winter Weather Advisory from 2 AM to 6 PM MST Thursday for
UTZ028.
&&
SHORT TERM...CC
LONG TERM...CC
AVIATION...15Hazardous Weather Outlook National Weather Service GRAND JUNCTION CO 457 AM MST Wed Dec 20 2017 COZ001>014-017>023-UTZ022>025-027>029-211300- Lower Yampa River Basin-Central Yampa River Basin- Roan and Tavaputs Plateaus-Elkhead and Park Mountains- Upper Yampa River Basin-Grand Valley-Debeque to Silt Corridor- Central Colorado River Basin-Grand and Battlement Mesas- Gore and Elk Mountains/Central Mountain Valleys- Central Gunnison and Uncompahgre River Basin- West Elk and Sawatch Mountains-Flat Tops- Upper Gunnison River Valley-Uncompahgre Plateau and Dallas Divide- Northwest San Juan Mountains-Southwest San Juan Mountains- Paradox Valley/Lower Dolores River- Four Corners/Upper Dolores River-Animas River Basin- San Juan River Basin-Southeast Utah-Eastern Uinta Mountains- Eastern Uinta Basin-Tavaputs Plateau-Arches/Grand Flat- La Sal and Abajo Mountains-Canyonlands/Natural Bridges- 457 AM MST Wed Dec 20 2017 This hazardous weather outlook is for eastern Utah and western Colorado. .DAY ONE...Today and Tonight Breezy and mild conditions can be expected today with a strong Pacific storm moving in tonight. This system will bring widespread snowfall to the region with moderate accumulations expected late tonight and through the day on Thursday. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday Snowfall will continue through Thursday afternoon, before ending Thursday night. Another fast moving storm will bring more snow and colder weather to the area Friday night and Saturday. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected today or tonight, however spotters are encouraged to report snowfall amounts to the National Weather Service in Grand Junction.
The national radar mosaic for the moment the first event began.
3 winter weather, 1 winter storm. Local standard time, as filed.
Snowfall amounts of 3 to 5 inches were measured from Fort Duchesne to the Vernal area.
Snowfall amounts of 5 to 8 inches were measured across the area.
Snowfall amounts of 6 to 10 inches were measured across the entire area which were record amounts in some locations for that time period.
Snowfall amounts of 3 to 6 inches measured across the area. Locally higher amounts included 9 inches at the Neck in Canyonlands National Park.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Utah in 2017Every state in 2017This day in weather historyWarnings in Utah, December 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: 726287, 726288, 726286, 726290.