A strong late season winter storm moved into Colorado on Thursday, May 20st, bringing much colder temperatures and heavy snow in and near the Colorado Front Range. Heavy, wet snow accumulated on trees which had already leafed out for the season, resulting in broken tree limbs and scattered power outages.
Every event with a place to put it; 13 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.
A strong late season winter storm moved into Colorado on Thursday, May 20st, bringing much colder temperatures and heavy snow in and near the Colorado Front Range. Heavy, wet snow accumulated on trees which had already leafed out for the season, resulting in broken tree limbs and scattered power outages. At one point Saturday morning May 22nd, nearly 100,000 customers along the Front Range were without power. Snow accumulated on roads in the higher terrain, and portions of I-70 west of Denver were shut down for a brief period of time. Total snow accumulations ranged from 1 to 11 inches across the Boulder and Denver metro areas, to 6 to 18 inches across the Palmer Divide, to between 6 to 24 inches across the foothills and mountains from Boulder County south through Park County.
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 May 19, 8:01 PM MST, 2 hours 59 minutes earlier.
Area Forecast Discussion National Weather Service Denver/Boulder CO 901 PM MDT Thu May 19 2022 .UPDATE... Issued at 852 PM MDT Thu May 19 2022 Cold front blasted through Denver with a puff of dust over the last hour. Winds are starting to drop off in the northern part now, and down to 15-25 mph north of Greeley. Still some dust in the air but that will be diminishing. Not much change to the forecast at this point, but we are going to change the start time of the Winter Storm Warning for the Denver to Fort Collins area to 4 PM Friday. Some snow may be beginning before then, especially in the higher parts, but there probably won't be any impact yet. && .SHORT TERM...(This evening through Friday) Issued at 241 PM MDT Thu May 19 2022 Long wave trough over the Pacific Northwest and Northern Rockies will dig south and be over the Great Basin and Central Rockies by Friday morning. A short wave trough embedded in the long wave trough near the Washington coast digs southeast into Utah by Friday. In addition to lift from the trough, a strong jet and frontogenesis will provide large scale ascent. At the surface a strong cold front pushes south across northeast Colorado this evening. Expect gusts to 45 mph to accompany the front. Then winds decrease, but remain a northeast upslope direction for tonight and Friday. The 12Z soundings across the Pacific Northwest and Northern Rockies showed the cold air in place and 700mb temperatures a little (~1C) colder then the models show. This cold air will track south with the trough move into the area late tonight and Friday morning. By 18Z, Friday 700mb temperatures fall to -5C to -7C. Cold enough for snow with moderate to heavy precipitation down to 5000 to 6000 feet MSL. All snow is expected for the foothills and mountains Friday due to this cold air. As the airmass continues to slowly cool, mostly snow is expected by late Friday afternoon across the Urban Corridor. For the Denver area, main point is at least a half inch of precipitation will fall as snow and more likely around an inch. The snow will accumulate on tree branches, causing broken branches and power outages if they happen to fall on/break power lines. Don't park under trees and avoid walking under trees. Travel is expected to become difficult in the mountains and foothills Friday afternoon. Winter Storm Watches will be upgraded to Winter Storm Warnings. Even if amounts don't reach criteria, the impacts of the heavy snow warrant the Warning. To the east of the Warning, plan to have a Winter Weather Advisory. .LONG TERM...(Friday night through Thursday) Issued at 241 PM MDT Thu May 19 2022 A high impact winter storm will be ongoing at the start of the long term forecast period, and this will be the timeframe in which the lower elevations sees the majority of its snow. While there is high confidence in the forecast for the Foothills and the rest of the high country, considerable uncertainty remains for the Denver metro. Let's dive in. As discussed in the short term discussion, snow will be ongoing across much of the high country as a potent storm system slowly moves across the forecast area. Aloft, northeast Colorado will be in the right entrance region of a 130-140kt jet streak, with a broad 500mb trough over the western United States. Embedded in this larger-scale trough, a robust shortwave is progged to swing east from southern Utah into Colorado overnight. Closer to the surface, upslope flow will continue to establish during the evening hours, with cold mid-level air slowly filtering in... with 700mb temperatures near -9 to -10C by midnight. The combination of the aforementioned synoptic scale ascent and deepening upslope flow/mid-level frontogenesis will set the stage for heavy snow for the high country and I-25 corridor Friday night. For the Foothills/High country... Heavy snow will continue in the evening and overnight hours, with banded snowfall likely. The heaviest snow will slowly shift south with time as the mid-level front sags south towards the Palmer Divide. Within the heavier bands, snowfall rates of 1-2 inches per hour looks likely. BUFKIT soundings show the dendritic growth zone deepening to about 10kft, which will be collocated with the maximum lift, resulting in efficient snow growth. Expect travel conditions to quickly detieorate as the sun sets, with considerable impacts to fully-leafed trees likely. HREF probability matched mean QPF from 6pm to midnight shows as much as an inch of liquid over the southern Foothills/Palmer Divide... which loosely translates to "a lot" of snow falling in a short window. PMM Snowfall also indicates the potential for 12 to 27 inches across the Foothills and 10 to 20 inches for the higher portions of the Palmer Divide. Slightly lower totals are expected on the west side of the divide, but low- end warning criteria should be met. For the Urban corridor and portions of the plains... The looming question in this forecast package is the transition time from rain to snow across I-25 and the Denver metro, with 12z guidance offering a variety of options, but little agreement. A few CAMS (namely the WRF-ARW and HRRR) are much warmer with boundary layer temperatures through roughly 03z, while others (NAM) are much cooler. We favor the colder side of guidance and argue that mostly snow will be falling at 00z/6pm with 700mb temperatures already cooler than -7C by this time. The other key question going into tomorrow is how quickly/efficiently snow manages to accumulate in the lower elevations. Guidance in general has slowly trended towards cooler overnight temperatures and more QPF in the overnight hours. Despite marginal surface temperatures, I'm slowly gaining confidence in a snowier solution for Denver. Even if most of this snow melts on hard surfaces, the 4-8 inches of wet snow on our foliage would cause tree damage and some power outages. Locations closer to the Foothills/Palmer divide will see the highest totals, with a sharp gradient in snow totals likely across the metro. By Saturday morning, our moisture will slowly be shifting out of the forecast area into southeastern Colorado, with snow ending from north to south through the late morning/early afternoon hours. Guidance has generally favored a slightly slower end time to the snow, and light accumulations are likely through Saturday. Temperatures will also struggle to make it out of the upper 30s or low 40s, with colder temperatures in the higher elevations. Overnight lows will be near to well below freezing across the area. The pattern stays relatively cool and unsettled into early next week, with another (weaker) shortwave bringing additional moisture by late Sunday. This moisture looks to stick around through at least Tuesday, though forecast guidance varies on the speed of this system. After this trough departs, warmer and drier weather will return as ridge begins to build over the west. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 852 PM MDT Thu May 19 2022 Northeast winds will decrease behind the cold front over the next few hours, down to 15 to 25 knots by 06z. Low clouds will develop overnight, with ceilings around 5000-6000 ft AGL expected by 09z and MVFR ceilings likely by 12z. Rain will develop by 18z with areas of IFR, changing to snow by early evening with widespread IFR conditions developing between 22z-02z. && .BOU WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning from noon Friday to noon MDT Saturday for COZ034-036-037-041. Winter Storm Warning from 4 PM Friday to noon MDT Saturday for COZ038>040. Winter Storm Warning from midnight tonight to noon MDT Saturday for COZ030-032-033-035. Winter Weather Advisory from midnight tonight to noon MDT Saturday for COZ031. Winter Weather Advisory from 6 PM Friday to noon MDT Sunday for COZ045-046. && UPDATE...Gimmestad SHORT TERM...Meier LONG TERM...Hiris AVIATION...Gimmestad
Hazardous Weather Outlook National Weather Service Denver/Boulder CO 823 AM MDT Thu May 19 2022 COZ030>051-201430- 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- 823 AM MDT Thu May 19 2022 ...LATE SPRING STORM TO BRING HEAVY SNOW TO THE FRONT RANGE MOUNTAINS, FOOTHILLS, AND URBAN CORRIDOR FRIDAY AND SATURDAY... This hazardous weather outlook is for northeast and north central Colorado. .DAY ONE...Today and Tonight Very dry, warm, and windy conditions will prevail today with critical fire weather across South Park, the Front Range Foothills east across the Urban Corridor and eastern plains. .DAYS TWO THROUGH SEVEN...Friday through Wednesday A late season snow storm will bring much colder temperatures and rain and snow to the mountains late tonight and continue through Saturday. The Front Range Mountains and Foothills above 7000 feet will see significant snowfall amounts which should produce hazardous travel conditions, tree damage, and possible power outages. The lower elevations will most likely see rain initially with a changeover to snow sometime Saturday morning. There is the potential for several inches of snow to fall across parts of the Front Range Urban Corridor and Palmer Divide which could lead to downed power lines and tree damage. However, there is still quite a bit of uncertainty in the snowfall amounts in these areas. In addition, temperatures will drop significantly Saturday night and Sunday night with sub- freezing lows possible. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed today or tonight.
The national radar mosaic for the moment the first event began.
11 winter storm, 2 winter weather. Local standard time, as filed.
Moderate to heavy snowfall accumulating 3 to 12 inches over about a day.
Light to heavy snowfall accumulating 2 to 11 inches over about a day.
Light to moderate snowfall accumulating 2 to 6 inches over about a day.
Moderate to heavy snowfall accumulating 6 to 23 inches over about a day.
Light to heavy snowfall accumulating 3 to 17 inches over about a day.
Light to heavy snowfall accumulating 1 to 11 inches over about a day.
Light to heavy snowfall accumulating 1 to 8 inches over about a day.
Moderate to heavy snowfall accumulating 6 to 22 inches over about a day.
Moderate to heavy snowfall accumulating 6 to 24 inches over about a day.
Moderate to heavy snowfall accumulating 6 to 24 inches over about a day.
Moderate to heavy snowfall accumulating 6 to 18 inches over about a day.
Moderate to heavy snowfall accumulating 3 to 12 inches over about a day.
Light to moderate snowfall accumulating 2 to 10 inches over about a day.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2022Every state in 2022This day in weather historyWarnings in Colorado, May 2022
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: 1017082, 1032258, 1032259, 1032254, 1032260, 1032296, 1032301, 1032249, 1032320, 1032261, 1032312, 1032321, 1032324.