A strong surface low tracked northeast across Southwest Idaho producing areas of heavy snow, particularly in the Treasure Valley.
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.
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 strong surface low tracked northeast across Southwest Idaho producing areas of heavy snow, particularly in the Treasure Valley.
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 Feb 22, 2:55 AM MST, 5 minutes earlier.
Area Forecast Discussion National Weather Service Boise ID 255 AM MST Thu Feb 22 2018 .SHORT TERM...Today through friday...Snow began shortly after midnight in southwest Idaho, a little earlier than expected. At 2 AM MST KCBX radar showed a nearly stationary band of snow over northwestern Ada County, ID, where at least one inch of snow has fallen already. NAM depicts this band especially well and GFS is also quite good. Both models keep snow going there through mid morning, but averaging in other models results in 3-4 inches total, locally 5 inches, total accumulation from about Eagle, ID, through Horseshoe bend, ID, i.e., at the upper end of advisory amounts. The rest of the Treasure valley should get 2-3 inches total snowfall through noon MST. A winter weather advisory has therefore been issued for the entire area, including the Owyhee Nountains. Lesser amounts of 1-2 inches are expected over the rest of southwest Idaho, and southern Malheur County, OR, mainly this morning. Less than an inch is expected in the rest of eastern Oregon, and the advisory issued earlier for that area has been cancelled. Later today the snow will shift to central Idaho as a cold front moves across from west to east. Snow will end from west to east this afternoon and evening with partial clearing. Breezy west/northwest winds Thursday night are expected to keep temperatures from dropping as far as they would with light winds above fresh snow cover. However, if the winds die down, Friday morning will be very cold. Latest MOS temps are not showing this. Friday looks mostly sunny in eastern Oregon, partly cloudy in southwestern Idaho, and mostly cloudy in south-central Idaho. High temps today and Friday should be in the 20s in the mountains to mid 30s in the warmest valleys. .LONG TERM...Friday night through Thursday...Models are in reasonable agreement until Monday night, showing a series of shortwave troughs moving over us in northwest flow aloft. The first will bring snow to the region Saturday, while the next follows rapidly and brings another round of snow Sunday night into Monday. The models diverge strongly after that time, with the EC digging a strong cutoff low south into southern CA before moving it back toward Utah next Thu. The GFS brings a broader trough into the PacNW and as a result backs our upper level flow to southwest. Some members of the GFS ensemble mimic the EC, but the majority back the operational run. At this time, we will keep a chance of snow over the region for Monday through Thursday, as either solution could end up being the most accurate, and the one thing they agree on is that we will remain in an active pattern with energy moving across the western US. Temps will remain below normal, both because of the general northwest flow aloft and also because of snow on the ground following not only today's system, but the ones that will follow. && .AVIATION...MVFR/IFR conditions as snow increases through 22/18Z. Mountains will be obscured. Conditions improve after 22/21Z, with VFR tonight except some mtns still obscured. Surface winds: generally 12 kts or less. Winds aloft at 10kft MSL: SW 15-20 kts, shifting to W 5-15 kts this afternoon. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...Winter Weather Advisory until noon MST today IDZ012-014-029-033. OR...Winter Weather Advisory until noon MST /11 AM PST/ today ORZ063. && www.weather.gov/Boise www.facebook.com/NWSBoise www.twitter.com/NWSBoise SHORT TERM...LC LONG TERM....SP AVIATION.....SP
The national radar mosaic for the moment the first event began.
1 heavy snow. Local standard time, as filed.
Reports of 5 to 6 inches of snowfall were received around the Boise area. Southeast Boise reported locally heavier amounts of 7 inches.
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, February 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: 731150.