A combination of snow and wind brought travel problems with localized heavy snow along with road closures and power outages.
Every event with a place to put it; 5 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 PIH wrote it up.
A combination of snow and wind brought travel problems with localized heavy snow along with road closures and power outages.
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 Pocatello, ID wrote its last area forecast discussion before the first event at Dec 29, 4:18 AM MST, 6 hours 42 minutes earlier.
Area Forecast Discussion National Weather Service Pocatello ID 418 AM MST Sat Dec 29 2018 ...CONFIDENCE INCREASING IN WINTER STORM BRINGING SIGNIFICANT SNOW ACCUMULATIONS AND VERY STRONG WINDS SUNDAY WITH MAJOR IMPACTS TO TRAVEL POSSIBLE... .SHORT TERM...Today Through Monday. TODAY: An elongated ridge of weak high pressure extends inland across the northern Rockies this morning. A notable amount of moisture is spilling over the top of the ridge across WA, OR, MT, and ID, and is illustrated quite well by morning regional radar imagery and model precip/QPF fields. Night satellite products show the associated cloud shield has expanded across almost all of the forecast area from the north and west, overtop some areas of low clouds and stratus. This is likely setting up a seeder-feeder effect, and sure enough, webcams and surface obs confirm light snow has broken out across portions of the Upper Snake Plain and the Island Park region/WY border, expanding to the south. We do carry anywhere from 25-65% PoPs and some light QPF over this region today with a dusting to 2 inches of snow possible, but the models may have slightly underestimated the seeder-feeder effect, especially early this morning. Trends will continue to be monitored for any needed forecast updates. No advisories are planned at this time. For the rest of the day, continued moisture spilling over the ridge will continue to produce areas of light snow, especially across our mntn ranges in SE Idaho, with the least activity expected from the Arco Desert SW into the eastern Magic Valley. Model consensus indicates Monida Pass, the Island Park region, and mntns surrounding the Teton Valley may see the most persistent activity, and have raised PoPs to 60-80% here. WINTER STORM: Confidence continues to increase that a winter storm will bring anywhere from light to significant snow accumulations and very strong winds across the region from tonight into Sunday, with major travel impacts likely. Overall model agreement continues to be quite good, and forecast confidence is solidly moderate and trending higher. Went aggressive with PoPs, blending the previous forecast with the NBM/NAMnest, and then increasing another 5-10% and broadbrushing a bit where models showed the best agreement in heaviest precip. PoPs are now 85-100% across portions of the western central mntns and eastern highlands. The heaviest snow is expected from the overnight hours into Sun morning, overlapping with the strongest winds which are expected from mid-morning Sun into Sun eve along and immediately behind the cold front associated with this system. SNOW ACCUMULATIONS: For snowfall (QPF), blended the previous forecast with the latest NBM/NAM (with the NBM weighted a bit heavier), and then made some manual adjustments to nudge toward the GFS and account for elevation. This resulted in very little overall change in the storm total snow forecast, perhaps nudging totals an inch or so lower in the valleys and an inch or so higher at some of the higher elevations. A widespread 4-7 inches is expected in the western central mntns/Stanley basin area and our eastern mntns and highlands in the area currently covered by the Winter Storm Watch, with more localized totals of 7-12 inches possible above about 6,500 feet. Much lighter totals of a dusting to an inch or two are expected in the eastern central mtns, Snake Plain, eastern Magic Valley, and western southern highlands (although 2-5 inches may fall above about 6,000 feet south of American Falls and Burley). STRONG WINDS: For winds, used a composite-tool that blended 80-90% magnitudes of the latest MAV/MET guidance as well as the NBM and NAM. Here too, this resulted in little overall change in the forecast, although a slight increase was noted over the Snake Plain/Arco Desert region into the western Caribou Highlands. The strongest winds with this storm are generally displaced from the areas of greatest snowfall, focusing on the eastern Magic Valley, Snake Plain/Arco Desert, and southern Highlands. Here, sustained winds of 25-35 MPH, with gusts of 40-50 MPH, will be possible, predominantly out of the south shifting to west behind the front, especially Sun afternoon. Winds may also reach these magnitudes at higher elevations of the eastern central mntns east of Stanley and Ketchum. Elsewhere, sustained winds of 15-25 MPH with gusts of 30-40 MPH are expected. It should be noted that we held winds a little shy of the latest MAV/MET in the Snake Plain. If significant mixing is realized with the front, a few higher gusts than currently forecast will be possible. We also let the NBM "light up" the peaks and ridgelines much higher than most other guidance, especially in the central mntns, which seems reasonable given strong wind profiles aloft. WARNING/ADVISORY DECISIONS: We very strongly considered upgrading the current Winter Storm Watch to advisories and warnings this morning, and issuing advisories across much of the rest of the forecast area. However, after extensive on-shift discussion and collaboration with neighboring offices, will hold off just a bit longer and let the current watch ride. This will allow the day shift to look over the forecast with a fresh set of eyes, evaluate one more model run, and issue everything with good collaboration with and at the same time as the neighbors. The combination of solid advisory-level to low-end warning level accumulations and strong winds may necessitate a warning in the eastern highlands watch area, while an advisory seems more likely in the western central mntns with slightly lower winds and snow totals. Despite only a dusting to an inch of snow expected in some portions of the Snake Plain and eastern Magic Valley, the strongest winds, solidly wind advisory-level, are forecast here, which could cause significant blowing snow and resultant significantly reduced visibilities and slick roads considering the available recent snowpack. For this reason, we are leaning toward issuance of a Winter Weather Advisory here as opposed to a Wind Advisory. Again, will let the day shift make these calls, so stay tuned. BOTTOM LINE: The combination of snow and wind is likely to create major travel impacts across almost all of our forecast area, even in areas where snow or wind alone wouldn't traditionally warrant an advisory or warning. Everyone is strongly encouraged to monitor the latest forecast and headlines that are issued, and plan on difficult travel Sun. Snow will taper off Sun afternoon, and winds will gradually slacken Sun eve. Mostly dry and unremarkable conditions are expected Mon. - KSmith/DMH .LONG TERM...Monday night through Saturday. Models remain in good agreement for this package. Upper trough continues to sag south through Utah to the 4-corners region Monday night into Tuesday, allowing ridge conditions to return to the region with a trend toward much colder temperatures. Guidance remains cold for Tuesday, Wednesday and Thursday mornings, with sub-zero readings for wider swaths of East Idaho, including all the way into the Lower Snake Plain. There is strong support for this with the ECMWF ensembles, so continued lower trend in forecast. Once again, potential for low clouds and fog will put a lid on how far the temps will drop, and still carrying that potential in the forecast. Headed into Thursday, ECMWF flattens ridge a bit with weak energy driving over the top and producing potential for light precipitation. Ensembles favor the stronger ridge solution of the GFS, with support from Canadian, so leaned into the drier solutions. Both ECMWF and Canadian shift a fast moving but weak shortwave trough through the PacNW Friday into Saturday, which flattens/keeps flat whatever remains of the rest of the ridge from their respective solutions. GFS remains much slower with these feature. Bottom line is that latter couple days of forecast period showing some uncertainty, and kept forecast trended toward the drier ensembles. - DMH && .AVIATION... Widespread stratus over East Idaho beginning to be overrun by mid level moisture ahead of incoming system. Some seeder- feeder light snows remain possible throughout the day with continued threat of MVFR ceilings/vis at KPIH/KIDA/KDIJ. Stronger system arrives overnight and into Sunday. Expect lowering ceilings and visibility as snow spreads across the region after 06Z tonight but especially into Sunday. Increased southerly downslope winds may hold off the precipitation a little longer at KPIH and KBYI, but that should fill in early Sunday. Winds will be a concern as well, approaching 25kts sustained in places with regions of blowing snow (both falling and existing snowpack), so expect visibilities to be a concern as well during the day Sunday. - DMH && .PIH WATCHES/WARNINGS/ADVISORIES... Winter Storm Watch from this afternoon through Sunday evening for IDZ060-062>066-072. &&
The national radar mosaic for the moment the first event began.
4 winter storm, 1 heavy snow. Local standard time, as filed.
Wind and heavy snow caused some Fremont customers to be without power on the 30th. The Island Park COOP observer recorded 12.3 inches of snow on the last 3 days of the month.
Heavy snow combined with wind and traffic caused 16,000 customers to be without power by the morning of December 31st. Saint Anthony recorded the heaviest snowfall with 9 inches.
State Highway 34 was closed between milepost 63 near Panting Lane and the Wyoming State line closed due to snow and wind with blowing snow. Swan Valley recorded 6.5 inches of snow.
A combination of snow and strong winds closed US Highway 30 from Lava Hot Springs east to Soda Springs on the 30th.
A combination of snow and strong winds closed US Highway 30 from Lava Hot Springs east to Soda Springs on the 30th.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Idaho in 2018Every state in 2018This day in weather historyWarnings in Idaho, December 2018
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: 798862, 798858, 798861, 798859, 798860.