Heavy mountain snow developed in the northern mountain over the Thanksgiving weekend, impacting the Interstate 70 corridor the most on the 23rd and 24th. Significant travel impacts occurred due to the adverse conditions and multiple accidents.
Every event with a place to put it; 9 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 BOU wrote it up.
Heavy mountain snow developed in the northern mountain over the Thanksgiving weekend, impacting the Interstate 70 corridor the most on the 23rd and 24th. Significant travel impacts occurred due to the adverse conditions and multiple accidents. Both east and westbound lanes at Loveland Pass were closed due to adverse conditions on the 23rd. Several multi-car crashes forced the closure of the I-70 west of the Eisenhower-Johnson Memorial Tunnels on the 24th. Two emergency shelters for motorists were opened in Summit County, where 80 people sought refuge.
Storm totals included: 28 inches at Mount Audobon; 26 inches near Rabbit Ears Pass; 23.5 inches, 9 miles south-southeast of Spicer; 21 inches near Loveland Pass and 6 miles west of Arapahoe Peak; 19.5 inches, 7 miles south-southeast of Cameron Pass and near Climax; 18 inches near Longs Peak; 17 inches, 9 miles east of Glendevy; 15.5 inches near Berthoud Pass and 9 miles south-southeast of Gould; 13 inches near Copper Mountain, Mout Zirkel and Winter Park; with 8 to 12 inches elsewhere.
Strong winds gusts in the high country spilled over across the northeast plains. Peak wind gusts generally ranged from 55 to 65 mph across the foothills and adjacent plains. Thousands of people in the Denver area are without power late in the evening of the 24th as the strong storm delivered powerful winds to the Front Range. According to Xcel Energy, roughly 8,100 customers were without power in Denver and the surrounding metro area. There were 43 outages in all, with most affecting fewer than 500 people. Peak wind reports included: 61 mph at Limon Municipal Airport, 60 mph at Centennial and Denver International Airport; 58 mph near Bennett, Buckley AFB and Natural Fort Rest Area.
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 Nov 22, 3:30 PM MST, 1 hour 30 minutes earlier.
Area Forecast Discussion National Weather Service Denver/Boulder CO 330 PM MST Thu Nov 22 2018 .SHORT TERM...(This evening through Friday) Issued at 330 PM MST Thu Nov 22 2018 Light snow is moving into the mountains on schedule this afternoon. We will see a continued pickup this evening with increasing moisture through a deep layer. However, the orographic component for our area is relatively limited given the west/southwest flow aloft. There is more instability associated with the short wave to our west, as observed on the radar and visible satellite images over Utah. As a result, we'll see snow showers continue, even as moisture shallows out and subsidence kicks in. For this first weather system through Friday, we expect most areas to see sub- Advisory amounts in the 2-6 inch range, but still some travel impacts with roads becoming snow covered and slick overnight as temperatures drop. Road conditions should improve on Friday with daytime insolation, except over a few of the high mountain passes. Locations around Rabbit Ears Pass and points north could see local amounts closer to 10 inches as orographics are certainly more favorable there. The big show for mountain snow and blowing snow starts tomorrow night. Winds will be the other concern in the short term. While we'll see relatively light winds through this evening, they pick up later tonight through Friday morning as the short wave trough passes by. Daytime heating, subsidence, and increasing gradients will bring a sharp uptick in winds across all areas by Friday morning. Using the max wind in the mixed layer as a proxy, we should see wind gusts into the 40-50 mph range across most of the plains. Winds in/near the Front Range Mountains and Foothills will be stronger with a bit of mountain wave enhancement, and that will also start a little earlier due to the mountain wave. There is relatively high potential for stronger downslope wind gusts to 60-75 mph, especially late Friday afternoon as the stable layer lowers to near mountain top. However, at the same time we should have some light snow ongoing in the mountains and that tends to break down the mountain wave enhancement. Also, the gradient is weakening during this period so it appears that ingredients are not coming together at this point for a high wind highlight. Will continue to monitor. .LONG TERM...(Friday night through Thursday) Issued at 330 PM MST Thu Nov 22 2018 A vigorous upper trough moving over the state from Friday through Saturday will produce a few days of active weather across north central and northeast Colorado. Frdiay evening will begin with orographic snow showers continuing in the mountains as moist, northwest flow aloft continues over the state. Saturday morning should see mountain snowfall increase again, ahead of the developing upper trough that is approaching from the Pacific Northwest. Cold advection will be increasing through the day as the upper trough axis approaches. Medium range models show the upper trough axis moving to northeast Colorado by 06z and further east after that. Snowfall intensities should drop off after that, but scattered activity should continue in the mountains. With the strong dynamics and abundant moisture, moderate to heavy snowfall should fall from Saturday afternoon into the evening. The upper level jet accompanying the trough will also produce strong winds over the higher elevations. Travel should be hampered by the moderate to heavy snowfall and poor visibilities due to blowing snow. The Winter Storm Warning for the mountains will continue through Saturday night. Improved conditions are expected Sunday as drier air moves in and snow shower activity decreases. The first half of next week should be drier as upper ridging builds over the western U.S. On the plains, dry conditions will continue through Friday night along with mild temperatures. Saturday afternoon will bring changes as the upper trough continues its track across the state. Strong surface cyclogenesis over southwest Kansas is forecast to occur which will increase the pressure gradients across the northeast Colorado plains. Wind gusts of 40 to 50 MPH will be possible late in the afternoon and evening. The upper trough will generate enough vertical motion for precipitation on the plains, but temperatures are expected to be warm enough to fall as rain. There will be some drying effects from the downslope flow which may keep things dry right along the foothills. Later Saturday night should see precipitation change over to snow on the plains as the pressure gradients relax and wind speeds begin to come down. From Sunday through the middle of next week should be dry and mild. Another upper trough will be approaching the state on about Wednesday, bringing a chance of snow back to the mountains. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 330 PM MST Thu Nov 22 2018 Main concern will be the winds. Through 06Z, generally light and variable winds should prevail, although there is a risk of a brief period of gusty west winds with virga moving off the Front Range. After 06Z, winds should trend more westerly and increase with gusts at KDEN increasing to around 20-25 knots toward 12Z, but closer to 30-35 knots at KBJC. Those winds will become solid west/northwest and increase further through 18Z. By then, wind speeds of 20-25 knots should be common with gusts around 35 knots at KDEN and KAPA, while KBJC could see gusts around 45 knots. Those winds may force east/west operations for a few hours 18Z-23Z at KDEN and limit arrival/departure rates. Until surface winds increase, there is potential for LLWS as flow aloft becomes much stronger. && .FIRE WEATHER... Issued at 330 PM MST Thu Nov 22 2018 Gusty northwest winds of 20-30 mph with gusts 40-50 mph across the plains on Friday will bring elevated fire danger. However, humidity levels should stay above critical Red Flag criteria, and closer to 20-25%. && .BOU WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning from 6 PM Friday to 5 AM MST Sunday for COZ031-033-034. Winter Weather Advisory from 6 PM Friday to 5 AM MST Sunday for COZ030-032. && SHORT TERM...Barjenbruch LONG TERM...Dankers AVIATION...Barjenbruch FIRE WEATHER...Barjenbruch
Hazardous Weather Outlook National Weather Service Denver/Boulder CO 1102 AM MST Thu Nov 22 2018 COZ030>051-231815- 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- 1102 AM MST Thu Nov 22 2018 ...WINTER STORM WATCH FOR THE NORTHERN COLORADO MOUNTAINS FRIDAY NIGHT THROUGH SATURDAY NIGHT... This hazardous weather outlook is for northeast and north central Colorado. .DAY ONE...Today and Tonight The first Pacific weather system will bring snow into the mountains late this afternoon through tonight. Some mountain roads are expected to become snow-packed and slippery tonight with snow accumulations of 2 to 6 inches by daybreak Friday. This weather system will also bring windy conditions tonight, with blowing and drifting snow over the higher mountains. Peak gusts in excess of 60 mph can be expected over the Front Range Mountains and Foothills, with gusts of 30 to 45 mph on the nearby adjacent plains and Wyoming border by late tonight. .DAYS TWO THROUGH SEVEN...Friday through Wednesday A series of weather disturbances moving across Colorado this holiday weekend are expected to produce periods of snow and strong winds across the high country of northern Colorado Friday through Saturday night. Snowfall may be heavy at times and winds of 45 to 65 mph may produce considerable blowing snow, especially over the higher passes and around the Eisenhower Tunnel. By late Saturday night, snowfall totals could range from 10 to 18 inches, with the highest amounts in the Park and Gore Ranges of Jackson and Grand Counties. The mountain valleys could receive 3 to 5 inches of snow. Sunday through Tuesday should be drier in the mountains, but another weather system is expected next Wednesday that will bring snow back to the forecast. It will be quite windy on the plains Friday and Saturday, with gusts up to 50 mph at times making travel particularly difficult across the northeast corner of the state. Some snow is possible on the plains Saturday afternoon and evening. Sunday through Wednesday should be drier again with less wind and gradually warming temperatures. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed today or tonight.
The national radar mosaic for the moment the first event began.
4 high wind, 3 winter storm, 2 winter weather. 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, November 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: 786672, 786673, 794358, 794363, 794364, 794359, 794360, 794361, 794362.