A cold northerly flow, associated with a strong upper level jet stream, combined with low level upslope to produce a period of moderate to heavy snowfall in and near the foothills. 3 inches was observed near Eldorado Springs, with 18 inches in northwest Boulder.
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The episode as NWS BOU wrote it up.
A cold northerly flow, associated with a strong upper level jet stream, combined with low level upslope to produce a period of moderate to heavy snowfall in and near the foothills. The heaviest snowfall focused over Boulder County where 19.3 inches was observed near Eldorado Springs, with 18 inches in northwest Boulder.
Storm totals elsewhere included: 16.5 inches at the National Weather Service in southwest Boulder; 15.5 inches near Genesee; 14 inches near Louisville; 13 inches, 2 miles southwest of Golden and Westminster, 11.5 inches in Kittredge and Lyons; 10 inches near Crescent Village, Erie, and Lafayette.
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 11, 7:30 PM MST, 3 hours 30 minutes earlier.
Area Forecast Discussion National Weather Service Denver/Boulder CO 830 PM MDT Sat Apr 11 2020 .UPDATE... Issued at 828 PM MDT Sat Apr 11 2020 A cold front was already moving into nern CO, as of 02z, and was south of a Carr to Sterling line. This front will move across most of nern CO by midnight the way things are going. Meanwhile another surge will move across after 09z with this feature enhancing upslope flow. In addition, as an upper level jet max moves across, should see increasing coverage of snow in the 09z- 12z period. On Sun, eventually the best focus for snow, will be in and near the foothills and along east facing slopes of the mtns, from the aftn into Sun night. Zone 39 may end up needing an advisory but haven't seen enough new data to upgrade at this point. && .SHORT TERM...(This evening through Sunday) Issued at 215 PM MDT Sat Apr 11 2020 Cold front currently over northern Wyoming will race south late this afternoon and evening. This puts the cold front through the Denver area around midnight. There may be a few showers ahead of the cold front this evening. Best chance will be over the mountains and far northern Colorado where there is some instability. Can't rule out a thunderstorm or two as well. Snow is expected to spread southeast behind the front late tonight and Sunday morning. The snow is expected to be short lived over the plains as the best lift and moisture slide off to the east. Surface high pressure centered over the Northern Rockies will keep a northeast wind in place across the Front Range. This upslope component is expected to keep light snow going through most of the day in and near the foothills. April sun and low snowfall rates will make it hard for roads to become icy during the daytime hours. However, the cold temperatures and loss of sun at night should lead to slick roads after dark. Snowfall amounts of up to 2 inches will be possible over the plains through Sunday afternoon. Upslope will keep snow falling over the mountains, foothills, and areas near the foothill through most of Sunday. Snowfall amounts of 4-8 inches are expected for the mountains and foothill through Sunday afternoon. Upslope areas between the foothills and plains are expected to see 2-5 inches by Sunday afternoon. This will not be the storm total however as additional light snow is expected Sunday night and Monday. .LONG TERM...(Sunday night through Saturday) Issued at 215 PM MDT Sat Apr 11 2020 By Sunday evening, the trough will have pushed off to the east with overall upper level flow continuing from the northwest. This will keep the region in the colder and wetter pattern through at least the middle of the week. Temperatures overnight Sunday will be quite cold with lows dipping into the teens creating a continued hazard to budding plants and trees. For Monday, there is a second batch of lift associated with a jet streak pushing from west to east. This will bring some snow across the plains into the evening Monday. Model cross-sections hinting at a short window of CSI and enhanced instability that could bring a quick 1-2 inches of snow. For the higher elevations the orientation of the upper level flow and moisture carried along with it will bring light snow to the mountains through the day with another 1-3 inches possible by Monday evening. Temperatures will continue to be on the cooler side with highs coming in just around freezing for the plains and teens and 20s for the high country. For Tuesday the northwest upper level flow continues with the models showing some drying by the afternoon. Models are hinting at some weak CAPE around so if there is enough moisture to work with could see some isolated diurnal showers by the late afternoon. Temperatures will rebound slightly with the continued warming trend with highs in the lower to mid 40s across the plains and 20s to 30s in the mountains. By mid-week models start to diverge on the placement and track of disturbances embedded in the flow aloft. The GFS pushes a handful of shortwaves through the region Wednesday night and again Thursday into Friday while the EC shifts the trough from Canada straight southward into the southwest region putting a ridge over the state. This will impact the confidence in temperatures toward the end of the week. Will most likely keep the previous forecast trend of more mild temperatures with a slight chance of precipitation through the week. The model discrepancies continue into the weekend with the potential of another storm system that could bring accumulating snow to the region. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 828 PM MDT Sat Apr 11 2020 A cold front will move across between 04z and 05z, at DIA, with winds increasing from the north to northeast. Gusts from 35 to 40 mph will be possible. Another surge will move in by 09z with light snow developing along with LIFR ceilings. Winds will be north with gusts from 30 to 35 mph thru 12z. && .BOU WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from midnight tonight to 6 AM MDT Monday for COZ033>036. && UPDATE...RPK SHORT TERM...Meier LONG TERM...Bowen AVIATION...RPK
Hazardous Weather Outlook National Weather Service Denver/Boulder CO 1056 AM MDT Sat Apr 11 2020 COZ030>051-121700- 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- 1056 AM MDT Sat Apr 11 2020 ...Snow and Cold Return Tonight... This hazardous weather outlook is for northeast and north central Colorado. .DAY ONE...Today and Tonight A strong cold front will push south across the area tonight. Temperatures will drop significantly and light snow will develop and become widespread early Sunday morning. Roads may become slick late tonight and into early Sunday morning. .DAYS TWO THROUGH SEVEN...Sunday through Friday The heaviest snow is expected in the mountains and foothills where 5 to 12 inches is possible through Sunday. Across the lower elevations, the heaviest snow fall rates will be in the 3 am to 9 am time frame. Overall up to 2 inches are expected with 2 to 5 inches for areas closer to the foothills. Roads will likely become slippery early Sunday morning due to the snow, cold and wind. Skies will clear overnight into Monday, allowing low temperatures to drop into the low teens to even single digits. The cold pattern and will continue next week. Snow will once again be possible late Monday and Tuesday. Another system may bring another round of accumulating snow Wednesday night and into Thursday. .SPOTTER INFORMATION STATEMENT... Spotter reports will not be needed today or tonight.
The national radar mosaic for the moment the first event began.
5 winter weather, 2 heavy snow. Local standard time, as filed.
Storm totals ranged from 4 to 8 inches.
Storm totals ranged from 5 to 9 inches.
Storm totals included: 15.5 inches near Genesee; 13 inches, 2 miles southwest of Golden; 11.5 inches near Kittredge; 10 inches near Crescent Village; 9 inches near Aspen Park; with 7.5 inches near Evergreen.
Storm totals included: 18 inches in northwest Boulder; 16.5 inches at the National Weather Service in southwest Boulder; 14 inches near Louisville; 13 inches in Westminster, 11.5 inches in Lyons; 10 inches near Erie and Lafayette; 9 inches near Longmont and Niwot; 8 inches in Broomfield; 6.5 inches in west Arvada; 6 inches in Lakewood, Littleton and Wheat Ridge.
Storm totals included: 19.3 inches near Eldorado Springs; 16 inches near Pinewood Springs; 15 inches near Jamestown; 13 inches, 4 miles northeast of Nederland; 11.5 inches in Meeker Park; 11 inches near Buckhorn Mountain and Rollinsville; 10 inches near Berthoud; 8 inches near Estes Park and Mishowaka.
Storm totals included 10 inches near Loveland, and 4.5 inches near Fort Collins.
Localized bands of heavy snow spilled into central Weld County. Storm totals included: 11 inches, 4 miles west of La Salle; 9 inches near Kersey, 6.5 inches near Mead, 5.5 inches near Firestone; 5 inches near Greeley.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2020Every state in 2020This day in weather historyWarnings in Colorado, April 2020
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: 882652, 882653, 882655, 883648, 883763, 883764, 883765.