A storm system brought heavy snow to the north-central mountains of Colorado. 5 inches near Alma and Guanella Pass.
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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 BOU wrote it up.
A storm system brought heavy snow to the north-central mountains of Colorado. Storm totals included: 15.5 inches near Cameron Pass, Loveland Pass and Rabbit Ears Pass; 14.5 inches near Climax and Longs Peak; 12 inches near Blue River, and Mount Zirkel; 11 inches near Brainard Lake and Ward; 9.5 inches near Alma and Guanella Pass.
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 Denver/Boulder, CO wrote its last area forecast discussion before the first event at Apr 5, 2:21 PM MST, 2 hours 39 minutes earlier.
Area Forecast Discussion National Weather Service Denver/Boulder CO 321 PM MDT Thu Apr 5 2018 .SHORT TERM...(This evening through Friday) Issued at 321 PM MDT Thu Apr 5 2018 Tonight and Friday's storm system remains on track as radars on the west slope are beginning to show the increasing moisture moving in from the west. The west-northwest flow aloft will be aided by an upper level jet in producing the rising vertical motions necessary to generate precipitation, first over the mountains, and then out onto the plains. The other piece of the puzzle will be a strong cold front moving in from the northeast during the morning hours. Upslope clouds are expected to develop Friday morning, after the morning commute. Scattered rain shower activity over the plains ahead of the front will quickly change over to snow as temperatures drop into the lower 30s before midday. Most of the precipitation with this event appears to be headed for the mountains, so only light accumulations are expected across the plains. The mountains will have a Winter Weather Advisory go into effect at midnight which will continue through midnight Friday night. East to northeast winds on the plains will be gusty for a few hours after the cold front passes. By late afternoon, the upper dynamics of the weather system will be moving east of Colorado, so precipitation on the plains should be winding down. Snowfall in the mountains will continue through the afternoon as moist, orographic flow continues. .LONG TERM...(Friday night through Thursday) Issued at 321 PM MDT Thu Apr 5 2018 Areas of light snow on the plains will slowly diminish Friday night as shallow upslope component wanes. Meanwhile, in the mountains, orographic forcing with 25-30 knots of west/northwest flow, sufficiently deep moisture, and neutral lapse rates will keep snow going, and we should see another 1-4 inches and travel impacts for the high country. As a result, we've extended the advisory there until midnight Friday night. On Saturday, warm advection kicks in as flat ridging develops across the Central Rockies. There should still be sufficient moisture for some rain and snow showers across the high country, but have reduced the QPF a bit from model averages as models typically overdo this in warm west/southwest flow. That should change significantly, however, by Saturday evening as the remnants of California's atmospheric river event reach the state. Deep and warm subtropical moisture will likely keep snow levels near 11 thousand feet early in the event, but several inches of snow expected up high. Cold advection finally arrives later Saturday night, dropping snow levels down to mountain valley floors and the higher foothills. Sufficient instability should allow some showers to spread across the plains but overall downslope pattern is expected to keep QPF amounts limited. In the mountains, expect snow totals around a foot at or just above the higher passes, with significantly lighter accumulations in lower elevations as the duration of snow will be limited by the initially high snow levels. By Sunday, drier air arrives with stronger and gusty downslope winds expected across the plains. Meanwhile, light snow showers will linger across the high country given orographic forcing and limited mid level moisture. There is potential for another wave and forcing associated with an upper level speed max for Sunday night which could bring an uptick in showers. Then, drier and warmer weather will develop by Monday and Tuesday with highs warming into the 70s across the plains by Tuesday. The warm weather should remain in the forecast through Wednesday although a passing wave could bring a few snow showers back into the high country. Models seem to have reasonable agreement on this. We'll be watching potential for another storm system by next Friday in this rather progressive weather pattern. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 321 PM MDT Thu Apr 5 2018 High ceilings are expected tonight with a mix of north winds in the evening and light drainage winds later on. A strpng cold front is expected to move through Friday morning, probably between 8 AM and 10 AM. Scattered rain showers may occur before the front, but after the front, ceilings are expected to drop below 1000 feet AGL and visibilities will drop below 3 miles in snow. Snow accumulations are expected to remain below a couple inches, especially on paved surfaces which should retain heat from the past few days. Snow accumulating on elevated surfaces could be 1 to 2 inches. && .BOU WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from midnight tonight to midnight MDT Friday night for COZ031-033-034. && SHORT TERM...Dankers LONG TERM...Barjenbruch AVIATION...Dankers
Hazardous Weather Outlook...UPDATED National Weather Service Denver/Boulder CO 1130 AM MDT Thu Apr 5 2018 COZ030>051-061730- Jackson County Below 9000 Feet- West Jackson and West Grand Counties Above 9000 Feet- Grand and Summit Counties Below 9000 Feet- South and East Jackson/Larimer/North and Northeast Grand/ Northwest Boulder Counties Above 9000 Feet- South and Southeast Grand/West Central and Southwest Boulder/ Gilpin/Clear Creek/Summit/North and West Park Counties Above 9000 Feet-Larimer and Boulder Counties Between 6000 and 9000 Feet- Jefferson and West Douglas Counties Above 6000 Feet/Gilpin/Clear Creek/Northeast Park Counties Below 9000 Feet- Central and Southeast Park County- Larimer County Below 6000 Feet/Northwest Weld County- Boulder And Jefferson Counties Below 6000 Feet/West Broomfield County- North Douglas County Below 6000 Feet/Denver/West Adams and Arapahoe Counties/East Broomfield County- Elbert/Central and East Douglas Counties Above 6000 Feet- Northeast Weld County-Central and South Weld County-Morgan County- Central and East Adams and Arapahoe Counties- North and Northeast Elbert County Below 6000 Feet/North Lincoln County- Southeast Elbert County Below 6000 Feet/South Lincoln County- Logan County-Washington County-Sedgwick County-Phillips County- 1130 AM MDT Thu Apr 5 2018 ...WINTER WEATHER ADVISORY FOR THE NORTHERN AND CENTRAL MOUNTAINS LATE TONIGHT THROUGH MIDDAY FRIDAY... This hazardous weather outlook is for northeast and north central Colorado. .DAY ONE...This Afternoon and Tonight Today will be warmer and drier ahead of a storm system moving in from the Great Basin. By 10PM tonight, rain and snow showers are expected to develop over the northern mountains. Any rain that develops in the mountains should turn to snow by 2 AM. Accumulations of 2 to 4 inches of snow are expected by morning, with the higher amounts on the high passes and west facing slopes. Over the plains, there will be a slight chance of rain transitioning to snow after midnight. .DAYS TWO THROUGH SEVEN...Friday through Wednesday A weather system moving over the state will bring snow to the mountains on Friday with additional accumulations of 3 to 6 inches. On the plains rain showers will change to snow Friday morning as colder air arrives behind cold front. At this time, several inches of snow and slick travel conditions can be expected in the mountains, while only light accumulations up to 2 inches and mainly wet roads are expected on the plains. Another wet but warmer storm system will move across the area Saturday night into early Sunday. Snow levels will start out relatively high across the mountains but then lower to valley floors Saturday night as colder air works across the state. Mostly rain showers can be expected across the lower foothills and plains. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed today or tonight.
The national radar mosaic for the moment the first event began.
3 winter storm. Local standard time, as filed.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2018Every state in 2018This day in weather historyWarnings in Colorado, April 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: 746215, 746217, 746221.