Our look back at this week is shorter than usual owing to the calmer weather we typically see this time of year. That isn’t to say however that there aren’t notable events like a tornado, lightning at the Adams County Fairgrounds that severely injured a man and the Fourmile Canyon wildfire.

From the National Weather Service:

5-9

In 1988…layers of smoke aloft from large forest fires in Yellowstone National Park completely obliterated the sun at times. At Stapleton International Airport…surface visibility was reduced at times to 5 and 6 miles in smoke.

5-13

In 2010…the Fourmile Canyon wildfire…northwest of Boulder… Broke out on the morning of the 5th. It originated from an unattended fire pit at a local residence. The wildfire quickly consumed 5 1/2 square miles or 3500 acres the first day…and forced the evacuation of over three thousand residents. Erratic 45-mph gusts sent the fire in two directions at times. Very dry weather conditions preceded the fire. The combination of strong winds…low relative humidities and dry fuels allowed the wildfire spread rapidly through the steep…heavily forested terrain. The flames were reportedly 20 to 50 feet in length. Towns within the burn area included Salina…Wallstreet and Gold Hill. The dry conditions coupled with gusty winds ranging from 45 to 64 mph persisted for several more days. Fire managers used as many as 700 firefighters and support personnel from 35 agencies and seven air tankers to battle the wildfire. A total of 6181 square acres or approximately 10 square miles were burned. The Fourmile Canyon wildfire was the most destructive fire in Colorado history in terms of the damage to personal property. It destroyed 171 homes with an estimated cost of 217 million dollars.

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In 1933…heavy rain in the foothills over the clear creek and Golden Gate Canyon watersheds caused flooding in Golden and damaged the roadway in Golden Gate Canyon… Which resulted in its closure.

In 1969…a funnel cloud was sighted in southeast Denver. There was also considerable thunderstorm activity and local heavy rain across metro Denver. Rainfall totaled 1.30 inches at Stapleton International Airport where small hail also fell.

In 1973…hail from 3/4 inch to 1 3/4 inches in diameter fell in Westminster and south of Broomfield.

In 2009…a man was critically injured when he was struck by lightning while riding his bicycle. He was nearing a paramedic van when he was hit. His heart stopped but paramedics quickly responded and were able to resuscitate him.

In 2011…a man was struck by lightning at the Adams County fairgrounds. He was leaning against a tree while watching a cross country meet when the tree was hit. The lightning traveled down the tree and up through the ground…using him as a conductor. The victim received second and third degree burns.

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In 1933…heavy rain over the Cherry Creek…plum creek…big dry creek…and little dry creek watersheds caused flooding on the South Platte River in Denver overnight. Nearly an inch of rain…0.98 inch…fell in the city.

In 1944…a trace of rain fell on each day. This together with a trace of rain on the 4th and 30th was the only precipitation for the month. The total of a trace of precipitation for the month equaled the driest September on record first set in 1892.

In 1994…unusually very warm weather resulted in three temperature records being equaled. High temperatures of 94 degrees on the 9th and 93 degrees on the 10th equaled record maximums for the dates. Low temperature of 63 degrees on the 9th equaled the record high minimum for the date.

Continue reading September 9 to September 15 – This Week in Denver Weather History →

Normally September is a relatively quiet month however we do occasionally see some extraordinary conditions. Our look back at this week in Denver weather history shows the earliest seasonal snowfall in Denver history, damaging lightning and the destruction of the Fourmile Canyon wildfire.

From the National Weather Service:

1-5

In 1995…record breaking heat occurred on the first 5 days of the month when the temperature climbed into the 90’s on each day. Record high temperatures of 97 degrees on both the 1st and 4th equaled the all-time record maximum for the month. High temperature of 95 degrees on the 3rd was a record for the date. High temperatures of 94 degrees on both the 2nd and the 5th were not records. The low temperature of 64 degrees on the 4th equaled the record high minimum for the date.

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In 1978…the temperature reached 90 degrees or more on seven consecutive days with the highest temperature…94 degrees… Recorded on both the 4th and 6th.

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In 1938…heavy cloudbursts in the foothills near the top of Genesee Mountain caused flash flooding on Bear Creek at Morrison. Nearly 8 inches of rain fell just north of Morrison in 6 hours and drowned 6 people in a car between Morrison and Kittredge. Damage was estimated at nearly a half million dollars. Flash flooding also occurred on south Boulder Creek in Eldorado Springs. Rainfall totaled 4.42 inches in Eldorado Springs…and rainfall was estimated to more than 6 inches in the foothills west of the town. Many buildings and residences were damaged in Eldorado Springs…and bridges were swept away. The high waters forced residents from their homes as far downstream as Erie. This was the flood of record on South Boulder Creek.

In 1973…hail to 3/4 inch diameter was reported in Boulder.

In 1987…lightning struck two men who were standing under a tree in downtown Denver. Both were seriously injured and hospitalized.

In 1996…lightning sparked a brush fire in the south buffer zone of the Rocky Flats Environmental Test Facility. No structures were damaged…but the fire burned about 100 acres of grassland before being contained.

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In 1892…there was a trace of rainfall each day. This… Together with a trace of rain on both the 7th and 8th…was the only rainfall of the month…making the month the driest on record. The monthly record was equaled in 1944.

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In 1901…a thunderstorm produced rain…hail of unknown size… And south winds sustained to 40 mph with gusts to 43 mph.

In 1961…Labor Day snow storm is the earliest date of the first snow…trace and measurable…of the season. The heavy wet snow broke many limbs from trees that were still in full foliage. The storm produced 4.2 inches of snowfall at Stapleton Airport with nearly a foot of snow in western suburbs and in the foothills. Minimum temperature of 33 degrees was a record for the date and the coldest ever recorded so early in the season.

In 1999…severe thunderstorms dumped large hail across metro Denver. Hail as large as 1 inch in diameter was measured near Cherry Creek in Aurora and near Bennett. Hail to 3/4 inch in diameter fell in the city of Denver.

In 2002…a thunderstorm produced a wind gust to 51 mph at Denver International Airport.

In 2003…very heavy thunderstorm rain washed out parts of the Virginia Canyon Road above Idaho Springs. Up to 4 feet of mud reportedly washed down the road during the storm. Several vehicles were trapped on the road. In Idaho Springs…several streets…including the main street… Were also buried in mud and gravel. Some buildings in town experienced minor flooding…including the basement of the town library and the police station.

Continue reading September 2 to September 8 – This Week in Denver Weather History →