Six EF-0 landspout tornadoes occurred in Weld County in the span of approximately one hour. The tornadoes tracked in a southeast to northwest direction over open country in an area from 5 miles east of Greeley to just east of Eaton.
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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.
Six EF-0 landspout tornadoes occurred in Weld County in the span of approximately one hour. The tornadoes tracked in a southeast to northwest direction over open country in an area from 5 miles east of Greeley to just east of Eaton. Three lasted less than 10 minutes, and the longest lived tornado was on the ground for 25 minutes and had a track length of 8 miles. Three farmsteads were impacted with minor damage, and there were no injuries or deaths.
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 20, 2:33 PM MST, 3 hours 5 minutes earlier.
Area Forecast Discussion National Weather Service Denver/Boulder CO 333 PM MDT Wed May 20 2020 .SHORT TERM...(This evening through Thursday) Issued at 333 PM MDT Wed May 20 2020 A dryline has setup across the eastern plains this afternoon from Lincoln to Weld Counties. This boundary hasn't been enough to generate cumulus clouds so storms are not expected to develop along it this afternoon. The only exception will be a couple storms along the eastern border of Lincoln County but those should not be in our CWA. As a cold front pushes through northern Colorado from the west late this afternoon and into the evening, it will meet up with better moisture on the east side of the dryline and create strong to severe thunderstorms. With mixed layer CAPEs expected to be around 2,500 j/kg and deep layer shear around 40 knots, these storms will be capable of producing hail up to 2 inches in diameter, damaging wind gusts, and a brief tornado. Therefore, a Severe Thunderstorm Watch was issued for Weld, Morgan, and Logan Counties until 10pm tonight. Storms are not expected to develop until after 6pm and they are not expected to occur west of Greeley. There remains a small chance a storm or two develops to the south of those counties near the Deer Trail area, but the chances were small enough to not include them in the watch. These storms will continue into the overnight hours across the far northern plains before moving out of Colorado by sunrise tomorrow. Winds have been very strong this afternoon across the forecast area with gusts up to 53 mph at DIA. These winds should continue through the rest of the afternoon before dying down in most locations after sunset. A cold front will move through northern Colorado this evening and could produce gusty westerly winds up to 50 mph across the northern Front Range foothills and northern I-25 corridor. Tomorrow will be much cooler with high temperatures 15 degrees cooler than today across the plains. With light winds expected, fire weather will not be much of a concern. A few light, high based showers may develop over the mountains and push across the urban corridor during the late afternoon. Little to no precipitation is expected from these showers although they could produce some winds gusts up to 30 mph. .LONG TERM...(Thursday night through Wednesday) Issued at 333 PM MDT Wed May 20 2020 The upper air pattern across North America will undergo a bit of transition through the upcoming week as a blocky trough-ridge- trough pattern becomes a western U.S. trough/eastern U.S. ridge from Friday through the weekend. Another shift to less amplitude and more progression appears to be in store for the first half of next week. These patterns look like they will only produce light precipitation for the most part. Friday looks particularly dry with temperatures warming to slightly warmer than normal. Southerly winds should also be on the increase as a low pressure trough develops over the I-25 corridor. High pressure ridging aloft should be enough to keep any shower activity capped. Saturday will bring another upper trough over the state with cooler temperatures aloft causing the airmass to become less stable. Daytime heating and dynamics aloft should be enough to produce isolated to widely scattered shower and thunderstorm activity. Sunday should be cooler in the wake of the upper trough moving onto the plains. From Monday through Wednesday...progressive flow will develop across the northern United States, but a cutoff upper low is forecast to linger over the southern plains. This will have the ability to move Gulf moisture up into eastern Colorado and either bring weak upper level ridging to the region or showery and unsettled conditions if the low retrogrades over the state. Temperatures should be around or slightly warmer than normal. A chance of showers will be mentioned on Monday and Tuesday, but Wednesday will be left dry for now. With the temperatures moderating and no particularly windy period identified, fire weather conditions should moderate back to typical May levels. && .AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon) Issued at 333 PM MDT Wed May 20 2020 VFR conditions are expected through Thursday as storm coverage is expected to stay east of the main TAF terminals today. Southerly winds are howling this afternoon with gusts up to 46 knots at DEN. A cold front will then push south out of Wyoming after 00z, with winds coming out of the northwest for a few hours before returning to drainage overnight. Winds will be light and out of the east- southeast on Thursday. && .BOU WATCHES/WARNINGS/ADVISORIES... Red Flag Warning until 9 PM MDT this evening for COZ214-216-241. && SHORT TERM...Danielson LONG TERM...Dankers AVIATION...Danielson
Hazardous Weather Outlook National Weather Service Denver/Boulder CO 1056 AM MDT Wed May 20 2020 COZ030>051-211700- 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 Wed May 20 2020 ...SEVERE STORMS POSSIBLE ON THE PLAINS LATE THIS AFTERNOON AND EVENING... ...RED FLAG WARNING SOUTH PARK...SOUTHERN FOOTHILLS...AND PALMER DIVIDE TODAY... This hazardous weather outlook is for northeast and north central Colorado. .DAY ONE...Today and Tonight Warm, dry and windy conditions will bring another day of critical fire weather conditions to South Park, the southern foothills and Palmer Divide. Outdoor burning of any kind is prohibited since humidity near 10 percent and winds gusting to near 40 mph would result in rapid fire spread. Elsewhere, southerly winds will be strong with gusts in the 30 to 40 mph. A dryline will set up across the eastern plains this with a small chance that strong to severe thunderstorms develop along it. As a cold front moves out of Wyoming this evening, there will be a better chance of severe thunderstorms Weld, Morgan, and Logan Counties. Main hazards will be damaging outflow winds and hail up to two inches in diameter. A cold front will push down across the area this evening, decreasing winds and also becoming the focus of training storms over the northeastern corner of the state until or just after midnight. Moderate to heavy rain, strong outflow winds and hail up to an inch will be the hazards, with a short-lived weak tornado possible. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday Only isolated thunderstorms are expected to develop Thursday, and will not be strong enough to reach severe limits. Winds will be lighter. Fire danger will increase again on Friday and Saturday with breezy and dry conditions. Some cooling can be expected by Sunday with a better chance of showers and thunderstorms. Then, mainly dry and warmer conditions are expected for the first half of next week. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed today and tonight.
The Denver radar (KFTG), 71 km away, was scanning. The volume nearest the first event began at 00:39 UTC.
6 tornado, 2 hail. Local standard time, as filed.
A landspout touched down briefly in an open field. No damage was observed.
A brief landspout caused minor damage to a farmstead. The tornado touched down just west of Weld Co 74/41. Barn doors were blown it and a fiberglass canoe lofted into a tree.
A landspout touched down near a farmstead and caused minor damage. It struck an irrigation pivot and twisted it.
A landspout touched down and caused minor damage to a farm located north of CO-392.|One aluminum shed sustained serious damaged.
A landspout tornado touched down and caused minor damage an older barn near county roads 72 and 43. The damage consisted of a wall blown over from an outbuilding.
A tornado touched down briefly in an open field. No damage was observed.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2020Every state in 2020This day in weather historyThe tornado archive for Colorado, 2020Warnings in Colorado, May 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: 890142, 890143, 890145, 890148, 890163, 895954, 884746, 884747.