Late spring and early summer weather hazards abound in Colorado. Looking back at this week in Denver weather history we see many examples including wildfires, deadly lightning, damaging lightning and dangerous flooding.

From the National Weather Service:

12-17

In 2000…two large wildfires developed in the Front Range foothills as careless campers and very dry conditions proved to be a dangerous combination. Strong winds gusting in excess of 60 mph on the 13th fanned the flames… Spreading both wildfires out of control. Winds gusted to 78 mph atop Niwot Ridge near the Continental Divide west of Boulder. The Hi Meadows wildfire…about 35 miles southwest of Denver…consumed nearly 11 thousand acres and 80 structures…mostly high priced homes. The Bobcat wildfire…located about 12 miles southwest of Fort Collins… consumed nearly 11 thousand acres and 22 structures. Late on the 16th…a strong cold front moved south over the great plains into northeastern Colorado. Low level upslope conditions developed in the wake of the front…producing 2 to 4 inches of snowfall overnight at elevations above 8 thousand feet. Firefighters were able to contain both fires shortly thereafter.

15-16

In 1963…heavy rain and hail ravaged metro Denver. In southeast Denver…heavy rain flooded homes and streets. Hail to a depth of 4 inches on the ground stripped trees and plants and drifted to depths of 3 to 4 feet in some areas. Flood waters on the valley highway were 19 feet deep in places…trapping many cars. Many creeks were running over their banks. On the 15th…the main thunderstorm cell passed over south Denver…dumping as much as 4 inches of rain in 90 minutes. Precipitation at Stapleton Airport totaled 0.91 inch on the 15th and 1.31 inches on the 16th. A funnel cloud was sighted briefly 4 miles to the south-southeast of Stapleton Airport on the 15th. Damage from hail and flooding amounted to near a million dollars.

15-17

In 2021…the temperature in Denver reached 100 degrees for three consecutive days: 101…100…100 respectively. Each established a new record high for the day. It was also the earliest occurrence of such a streak. A record high minimum of 68 also occurred on the 17th.

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In 1950…very heavy rain and hail storms in southwest Denver caused an estimated 750 thousand dollars in hail and flood damage. Thunderstorms produced 2.06 inches of rain at Stapleton Airport with 2.23 inches of rain measured in downtown Denver.

In 1965…a tornado…15 miles south-southeast of Denver… Touched down and damaged two houses in northern Douglas County. Three golfers at a country club and a women who lived north of Castle Rock were injured by falling structures.

In 1983…a microburst wind gust to 54 mph was recorded at Stapleton International Airport.

In 1984…a tornado touched down briefly in Parker. No damage was reported.

In 1986…lightning injured 5 people just north of the Denver city limits in Adams County. The victims were members of a drum and bugle corps and were standing near a metal scaffold. Heavy rain from the storm also caused street flooding in the metro area.

In 1991…hail to golf ball size fell at Conifer.

In 1992…a rare mid-June high wind event wreaked havoc over metro Denver when a pacific cold front moved across the Rocky Mountains. Strong winds at speeds of 40 to 50 mph were common along the Front Range foothills. Winds reaching 107 mph in the foothills west of Denver and 79 mph at Longmont…caused damage ranging from trees being toppled to large trucks being rolled over. Strong winds estimated at 75 mph rolled a 35-foot truck carrying building supplies on U.S. Highway 36 north of Boulder. The truck driver and a passenger as well as the driver of another car were slightly injured. The winds downed power lines. The gambling towns of central city and Blackhawk were without power for a couple of hours. West winds reached 43 mph at Stapleton International Airport.

In 1996…a small tornado touched down in the foothills southwest of Boulder near Pinecliffe…knocking down 50 to 100 large pine trees. A house nearby sustained damage when shingles were ripped from the roof. The tornado also picked up a 17-foot sailboat with attached trailer and carried it 25 feet into a nearby tree. In addition… Thunderstorm wind gusts to 46 mph were measured at Denver International Airport.

In 2004…hail as large as 1 inch in diameter fell near Castle Rock. Hail to 3/4 inch was measured near Bennett.

In 2005…severe thunderstorms produced hail as large as 1 inch in diameter in Centennial.

In 2011…severe thunderstorms produced and damaging across parts of metropolitan Denver. In Lakewood…a tree blew down and landed on at least five cars. At Centennial Airport…a section of a roof on a hangar was ripped off the strong winds. A peak wind gust of 46 mph was recorded at Centennial Airport and Denver International Airport in the evening.

In 2022…severe thunderstorms produced large hail across parts of Boulder and Weld counties. The hail ranged from 1 to 1 1/2 inches at Allenspark…Ft. Lupton…Hudson and Lochbuie.

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In 1965…on the afternoon and evening of the 16th…violent thunderstorms produced extremely heavy cloudbursts of rain over the palmer divide and sent a wall of water as high as 20 feet down both branches of Plum Creek into the South Platte River and through metro Denver. The heavy rainfall produced the most devastating flood in the history of Denver. Rainfall totaled 14.0 inches in 3 hours at both Larkspur and Palmer Lake with 12.0 inches recorded in Castle Rock. The flood waters caused extensive damage to roads and bridges in larkspur…Castle Rock…and Sedalia…including washing out the I-25 bridge over East Plum Creek in Castle Rock. The citizens of metro Denver received reports of the flooding to the south and had a few hours to initiate evacuation procedures along the South Platte River…greatly limiting the loss of life. By evening…the flood reached Littleton where a heroic effort was made to save nearly 150 horses at the Centennial Racetrack…which was completely inundated by the flood waters. As the flood proceeded through the city of Denver…the river became more than 1/2 mile wide and destroyed all homes…trailer courts… And businesses in its path. The waters contained debris ranging from refrigerators to old cars. As many as 26 bridges were damaged or destroyed…including the 6th Avenue freeway bridge across the South Platte. Both Public Service Company power plants were shut down by the flood. The King Soopers grocery chain bakery was inundated. About midnight… The torrent crested at 25 feet above normal with flow exceeding 40 times normal and is the record flood on the South Platte and many of its tributaries. The flood caused 230 million dollars in damage and 8 deaths along the entire South Platte River basin. The intense rain also caused flooding along Cherry Creek in Denver…on Toll Gate and Sand Creeks in east metro Denver…and on Kiowa and Bijou creeks to the east of Denver. The South Platte River flood closed nearly every major east-west highway into Denver…nearly isolating the city. The flood caused heavy damage to state and county roads in the area. Railroads were also hard hit with the main yards in lower downtown inundated. Sewerage… Water supply facilities…and irrigation works also received heavy flood damage. The flood crest did not reach Nebraska until the 20th.

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In 1915…northwest winds were sustained to 41 mph with an extreme velocity to 42 mph.

In 1967…this was the 24th consecutive day with a trace or more of precipitation from May 25th. Precipitation totaled 5.87 inches during the period…more than a third of the average yearly total.

In 1975…hail more than 2 inches in diameter fell in eastern Aurora.

In 1977…golf ball size hail was reported 3 miles east of Arapahoe County airport…now Centennial Airport. Heavy hail to 3/4 inch in diameter was reported in Littleton… Castle Rock…and Sedalia.

In 1979…a man and a girl were struck and killed by lightning while walking in a park in northwest Denver.

In 1987…3/4 inch hail fell near Boulder.

In 1991…a microburst wind gust to 59 mph kicked up some blowing dust at Stapleton International Airport.

In 1998…hail as large as 3/4 inch in diameter fell in Boulder.

In 2003…lightning struck a feeder line…knocking out the electricity to about 3000 residents in Littleton. A lightning strike caused minor damage to the roof and attic of a home in Lafayette. Another lightning strike caused minor roof damage to a residence in Louisville. Yet another lightning strike hit a home in Denver and caused a small attic fire. Hail as large as 1 inch in diameter was measured near Centennial Airport and near Greenland.

In 2009…hail up to 1 inch in diameter was measured near Longmont.

In 2015…a severe thunderstorm produced hail up to 1 1/2 inches in diameter near Arapahoe Park…and up to 1 inch in diameter near Parker.

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In 1964…high winds at speeds of 50 to 60 mph with gusts as high as 75 mph caused damage to homes…power lines…and trees in Boulder. Non-convective west winds gusting to 46 mph caused some blowing dust at Stapleton International Airport on the 17th.

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In 1875…a windstorm produced sustained winds to 45 mph during the morning hours. Numerous forest fires along the base of the mountains were visible from the city.

In 1886…northwest winds sustained to 40 mph were the strongest of the month that year.

In 1987…severe thunderstorms produced lightning…large hail… A tornado…heavy rain…and strong winds across metro Denver. Rainfall totaled 2.50 inches in an hour in Wheat Ridge… Causing minor flooding. I-25 was flooded in north-central Denver…snarling traffic. Hail 7/8 inch in diameter fell in Louisville with 1 1/2 inch hail near Golden and 1 to 1 3/4 inch hail in and near Castle Rock. A tornado touched down briefly in Castle Rock. No damage was reported. Lightning started a small fire that burned half a cabin near Evergreen.

In 1994…a funnel cloud was sighted over Aurora; hail to 1 3/4 inch diameter fell near Brighton; and hail over an inch in diameter fell over Aurora…southeast Denver… Louisville…and Boulder. Lightning struck a home in Henderson 9 miles north of Denver and knocked a hole in the roof…which caused the ceiling to collapse. Hail to 1 1/4 inch diameter was measured at Stapleton International Airport.

In 2002…the Hayman wildfire in the foothills to the southwest of Denver intensified…and the winds aloft carried the smoke plume directly over metro Denver…again creating a dense haze of smoke which blocked the sun. Surface visibilities were again reduced to as low as 1 1/4 miles at Denver International Airport.

In 2004…severe thunderstorms produced hail to 3/4 inch in diameter near Morrison…in Littleton…near Conifer…near Castle Rock…and in Aurora near Cherry Creek.

In 2013…a landspout tornado touched down at DIA. The tornado sent 10 thousand travelers on the concourse…on planes and in the terminal scrambling to get into tornado shelters. The tornado formed just to the south of Runway 35R and then moved slowly northwest between Runway 35R and 35L…and moved to within one third of a mile of Concourses A and B before dissipating. The tornado moved extremely close if not over the ASOS (Automated Surface Observation System) and another low level wind shear sensor at DIA. The ASOS weather observing system reported a 97 mph wind gust…while the wind shear sensor reported a wind gust to 109 mph at the same time indicative of an EF1 tornado. There was only minor damage noted to the equipment. Nine flights were diverted elsewhere during a tornado warning. Severe thunderstorms also produced large hail up to quarter size in Adams and Weld Counties.

In 2014…a severe thunderstorm produced large hail up to quarter size near Buckley Air Force Base. At Denver International Airport…a peak wind gust to 55 mph was observed from the southwest…along with 0.37 inches of water.

In 2015…a severe thunderstorm produced hail…from quarter to half dollar size…near Lafayette…Louisville and Superior.

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In 1874…during the afternoon…large columns of smoke from extensive fires in the mountain forests moved over the city from the west and southwest.

In 1875…while no precipitation was measured in the city… Rainfall over the palmer divide caused Cherry Creek to rise to the highest level in 10 years.

In 1977…hail up to 2 inch diameter damaged two patrol cars in Castle Rock.

In 1983 golf ball size hail fell just north of Bennett.

In 1990…lightning from a thunderstorm struck the roof of a house in south Boulder. Residents of the house were able to extinguish the ensuing fire with a garden hose…but not before several shingles had burned.

In 1992…thunderstorms produced hail up to 2 inches in diameter in central Douglas County near Castle Rock. Hail was 3 inches deep on I-25 south of Castle Rock. A funnel cloud was sighted near Parker.

In 1997…a 66-year-old man was knocked unconscious by a bolt of lightning while he was golfing at the eagle country club in Broomfield.

In 2000…dry microburst winds gusting to near 70 mph were reported across southeast Boulder and northern Jefferson counties. Peak wind gusts included: 68 mph at the national wind technology center…67 mph at Jefferson County Airport… And 65 mph in Broomfield.

In 2001…severe thunderstorms produced large hail in the foothills southwest of Denver. Hail as large as 1 3/4 inch in diameter fell near Conifer and Bailey.

In 2002…lightning damaged the Evergreen Fire Protection District radio repeater. One microwave transmitter…the main fire channel transmitter…and two solar panel controllers were destroyed. Lightning struck a garage and caused a small fire. Two vehicles parked in the garage were damaged. Hail to 3/4 inch in diameter fell near Castle Rock.

In 2004…severe thunderstorms produced hail to 3/4 inch in diameter near Castle Rock…Larkspur…and Golden.

In 2018…very large hail pummeled portions of the Front Range Urban Corridor and extended across the northeast plains of Colorado. Reports of collapsed roofs due to hail were reported…with major hail portions of the Denver metro area. The Rocky Mountain Insurance Information Association estimated the property damage from the storm totaled 276.4 million dollars…making it the 8th costliest hailstorm to strike the state to date. In Denver and the surrounding metro area…hail sizes included: 3 inch diameter in Englewood; 2 3/4 inch in Greenwood Village; 2 inch at Aurora Cherry Creek…4 miles south of Glendale and near Smoky Hill; 1 3/4 inch just east of Denver International Airport and near South Glenn; 1 1/2 inch near Niwot; and 1 inch diameter hail in Southwest Denver and 5 miles northeast of Parker.

In 2022…a microburst wind produced a peak gust to 55 mph at Denver International Airport from the west. The visibility was briefly reduced to one half of a mile.

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In 1875…smoke from several large forest fires in the mountains was visible from the city on each of these days.

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In 1888…northwest winds were sustained to 44 mph.

In 1956…a microburst caused a brief wind gust to 58 mph at Stapleton Airport.

In 1964…hail up to 1 inch in diameter was reported 1 mile north of Stapleton International Airport. A 3 minute hail storm at both Stapleton International Airport and Lowry Field piled small hail to one half inch deep.

In 1967…a strong thunderstorm dumped 1.95 inches of rain in less than an hour at Stapleton International Airport and produced a wind gust to 54 mph. The storm caused some flooding in east Denver and Aurora. There was widespread flooding to streets…basements…and store buildings and automobiles. Hail stones to 3/4 inch in diameter were measured at Buckley Field in Aurora. A tornado touched down just south of Littleton…damaging a barn and killing several head of cattle.

In 1985…a wind gust to 61 mph was reported at Golden Gate Canyon in the foothills west of Denver.

In 1986…a man was killed by lightning at Highlands Ranch south of Denver.

In 1987…several tornadoes were sighted across metro Denver. A tornado touched down briefly 5 miles west of Parker. A tornado was sighted just north of Chatfield Reservoir. A tornado just northwest of Watkins was on the ground for 15 minutes. A tornado near Barr Lake was taped by a television news crew. It had a double vortex and was on the ground for about 10 minutes. In addition to the 4 tornadoes…severe thunderstorms dumped large hail across metro Denver. One inch hail was reported in southeast Aurora; 3/4 inch hail fell at the Denver Technology Center…Buckley Field…and Franktown.

In 1992…several short-lived tornadoes occurred in the vicinity of Barr Lake. No injuries or damages were reported. A water spout was sighted over the southern end of Barr Lake. Funnel clouds were also sighted on the grounds of the rocky mountain arsenal by national weather service observers at Stapleton International Airport.

In 1994…hail up to dime size covered I-25 south of Denver and near Sedalia. Heavy rain caused local flooding on the interstate highway.

In 1996…strong thunderstorm winds downed several large tree limbs in Boulder on the University of Colorado campus. A stop light in the city was also blown down.

In 1999…lightning sparked an oil tank fire near Brighton.

In 2001…large hail driven by strong thunderstorm winds raked Denver international and Front Range airports. Wind gusting to 54 mph along with hail as large 2 inches in diameter punched at least 14 thousand holes and cracks in the flat roofs of several buildings at Denver International Airport. In addition…93 planes and hundreds of cars were damaged. About 100 flights had to be cancelled…stranding 1500 travelers. The airport was completely shut down for about 20 minutes. The storm also damaged a ground avoidance radar used to track planes on the ground to prevent collisions. Damage was estimated at 10 million dollars…not counting the damage to the 93 airliners. The storm moved south and struck Watkins with hail as large as 2 1/2 inches in diameter and winds gusting to 60 mph. A least 30 private planes at Front Range airport were destroyed. The radome protecting the National Weather Service doppler radar…which was tracking the storm…also sustained damage. The large hail…damaging winds…and heavy rain pummeled a mobile home park near Watkins. In the park…52 mobile homes…14 recreational vehicles…3 homes…and a commercial building were damaged. Siding was riddled with holes and windows were broken. Vehicles sustained extensive damage and car windows were shattered. A handful of people were treated for minor cuts and bruises. The strong winds also flipped a tractor trailer along I-70 near Watkins. The storm caused power outages…which affected about 1200 residents. Excluding the damage at Denver International Airport…damage estimates totaled 49 million dollars…making the storm the costliest in the last 3 years and the 10th costliest since 1984. A small tornado touched down just east of Brighton… But did no damage. Hail as large as 2 inches in diameter fell near Fort Lupton with 3/4 inch hail measured in Bennett. Precipitation from the storm totaled only 0.23 inch at Denver International Airport.

In 2002…heavy rain fell near the Hayman wildfire burn area. Flash flooding washed out a 40-foot section of the access road to Cheeseman Reservoir. Some debris was washed against a gate…blocking the road. Hail to 1 1/2 inches in diameter fell near central city with 3/4 inch hail near Blackhawk.

In 2003…hail as large as 1 inch in diameter fell near Bennett and Strasburg with 3/4 inch hail measured in Denver…Golden… At Centennial Airport…and near Parker. Hail as large as 7/8 inch was reported in Arvada.

In 2004…a severe thunderstorm produced hail to 3/4 inch in diameter in and near Brighton.

In 2005…severe thunderstorms produced large hail near the palmer divide. Hail to 1 inch in diameter was measured near larkspur with 7/8 inch hail near Sedalia and 3/4 inch hail in Greenland. An apparent thunderstorm outflow produced a wind gust to 59 mph at Denver International Airport during the evening hours.

In 2010…lightning struck a home in Centennial and sparked a fire which caused extensive damage.

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In 1897…high winds raked the city overnight. Southeast winds were sustained to 60 mph with gusts as high as 72 mph on the 20th. Southeast winds were sustained to 57 mph with gusts to 60 mph on the 21st.

In 2007…a brief hot spell produced two temperature records. The high temperature of 97 degrees was tied on the 20th. A new record high temperature of 99 degrees was established on the 21st.

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In 1927…north winds were sustained to 40 mph with gusts to 44 mph.

In 1984…lightning struck and killed two children standing near a tree in a backyard in Lakewood. Strong thunderstorm downbursts caused a wind gust to 58 mph in Northglenn and knocked down two power poles near Brighton.

In 1988…lightning struck a home in Denver…causing about ten thousand dollars damage. Lightning damaged 3 homes in Littleton…and also hit a house in greenwood village that had been struck by lightning 7 years previously.

In 1991…thunderstorms produced widespread hail across metro Denver. Hail as large as 2 1/2 inches fell at several locations across southwest metro Denver. One storm spotter reported hail 8 inches deep near the intersection of I-25 and c-470. Heavy rain with the storms caused some street flooding. In Commerce City…several cars were under water… And in Westminster a police officer reported water up to the doors of his car. Damage to homes and automobiles totaled 55 million dollars.

In 1992…a tornado touched down briefly near Bennett. Another tornado was briefly on the ground near Strasburg.

In 1994…heavy thunderstorm rains caused flooding in metro Denver. Several vehicles were stalled in the high water on I-25. Lightning struck an underground natural gas line in Aurora…causing a fire. Widespread power outages were also observed.

In 1996…three homes were struck by lightning in Parker. The lightning struck the garage of the first home…which started a small fire that burned some siding and spread into the attic. A second home sustained damage to the attic when a small fire was started. The third home received only minor damage. Lightning also sparked two small grass fires in the area. A man in Lakewood received minor injuries when he was struck by lightning while working on a ladder. A funnel cloud was sighted in Castle Rock. Strong thunderstorm winds downed a large tree near crossroads mall in Boulder. A small tornado (F0) briefly touched down near Lafayette. No damage was reported.

In 1997…one inch diameter hail was measured in Boulder.

In 2002…a thunderstorm wind gust to 62 mph was recorded at Denver International Airport.

In 2005…severe thunderstorms produced hail to 1 inch in diameter in Broomfield along with 3/4 inch hail near Arvada.

In 2006…a man riding a motorcycle was struck and killed by lightning on U.S. Highway 36 between Church Ranch Blvd. and Sheridan Blvd. In Westminster. After the biker was struck…he and his motorcycle crashed into the center concrete median of the highway. The lightning bolt left a crater in the highway asphalt that measured 18 inches long…8 inches wide and 4 inches deep.

In 2010…a severe thunderstorm produced hail up to 1 1/2 inches in diameter near Morrison. In Lafayette and Louisville…hail up to one inch in diameter was observed.

In 2014…three small tornadoes touched down in eastern Adams County near Barr Lake…Bennett and Front Range Aiport. The tornado near Barr Lake damaged some out buildings and a storage shed. Minor roof damage to houses in the immediate area was reported near 168th Ave and Haymont Rd near 168th Ave and Haymont Rd. It was rated an EF1. The others did no damage.

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In 1941…strong thunderstorms produced cloudbursts of rain in Boulder County…starting during the late evening of the 21st and continuing overnight. The heavy rains over the Boulder Creek…left hand creek…and South St Vrain River basins produced flooding in already swollen streams and turned dry gulches into raging torrents. The force of the floodwaters swept a man from the arms of his wife to his death…severely damaged canyon homes and swept others away… And hurtled a car down a steep embankment after the driver narrowly escaped. West of Boulder…the Boulder canyon highway was littered with rocks and debris and collapsed when two culverts were washed away. The flood waters washed much debris down four mile canyon…damaging the road near the creek bed. A bridge over dry creek just south of Niwot was completely washed away.

In 1964…scattered hail and rain caused property damage and local flooding in Boulder.

In 1989…an unseasonably cold weather system produced strong winds over much of metro Denver and snowfall in the foothills as low as 7500 feet elevation. One to 6 inches of snow fell in the foothills west of Denver with 15 inches reported on the summit of Mount Evans. Six inches of snow were measured at Conifer. Rainfall totaled only 0.09 inch at Stapleton International Airport where northwest winds gusted to 29 mph on the 21st.

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In 1872…small sandstorms…frequently seen on the prairie… Occasionally passed through the city.

In 1983…3/4 inch hail was observed at Deckers…and a thunderstorm produced wind gusts to 55 mph at Littleton.

In 1988…a tornado was spotted one mile east of Brighton; it remained on the ground for about 6 minutes…but did no reportable damage. Lightning damaged a home near Castle Rock.

In 1991…thunderstorms produced golf ball size hail in Lafayette. The strongest storms occurred north of metro Denver.

In 1992…nickel size hail was reported just east of Parker.

In 1995…large hail 3/4 to 1 3/4 inches in diameter fell in Castle Rock where a funnel cloud was sighted. Hail 3/4 inch to 1 inch in diameter fell in south Denver and Aurora. A funnel cloud was also sighted over Chatfield Reservoir. In Bennett…very strong dry microburst winds of unknown speeds ripped a 14- by 48-foot metal roof off of a barn. The roof was tossed approximately 250 yards. A few 150- pound railroad ties were moved 10 to 15 feet.

In 1997…a tornado touched down near the Adams County Fairgrounds northeast of Denver…uprooting several trees and damaging a car. A dry microburst produced a brief wind gust to 69 mph at Jefferson County Airport. A small brief tornado was sighted near Hudson…but did no reported damage.

In 1998…3/4 inch hail fell near Hudson.

In 1999…thunderstorm winds gusted to 63 mph at Denver International Airport.

In 2003…hail as large as 2 inches in diameter was measured in Fort Lupton with 3/4 inch hail in erie and near Boulder.

In 2006…a small tornado (f0) touched down near Franktown… But caused no damage.

In 2008…strong winds from dry microbursts developed over parts of southern weld and western Arapahoe counties. A peak gust of 60 mph was observed in Centennial. Near Frederick…strong winds snapped 3 power poles and sparked a small grassfire near State Highway 52 and interstate 25. At Denver International Airport…a peak gust of 31 mph was observed.

In 2009…hail up to 2 inches in diameter was observed near crescent in Boulder County.