Change is of course the one constant in Denver’s weather but come July, things actually get pretty consistent. The standard formula for a day in July is a sunning morning, clouds developing in the late morning and early afternoon. Come mid-afternoon, thunderstorms are rolling off of the foothills and into the metro area and the eastern plains. These storms do occasionally reach severe status containing hail, gusty winds and heavy downpours of rain.
In fact, the worst hail storm on record in Denver history hit western sections of the city on July 11th, 1990. Baseball and softball sized hail from this ferocious storm caused millions of dollars worth of property damage.
July is the most stormy month of the year in fact with thunderstorms occurring on average 11 days per month – or once every three days. These slow moving storms are one of the reasons July is Denver’s second rainiest month with an average of 2.16 inches of rain (second only to May). However, these storms are also often very localized and cause widely varying precipitation amounts across the metro area. It is not unusual for one area of down to be deluged while others remain entirely dry. With these severe storms, flash flooding remains a possibility.
June 28 to July 4 - This week in Denver weather history
As always, an interesting week in Denver and Thornton weather history. Various severe weather items are noteworthy, none more so than on July 2, 2006 when a teenager wearing an iPod was struck with lightning. The music player actually contributed to the teen’s injuries by providing a direct route for the electricity into the victim’s head via the headphones.
From the National Weather Service:
21-3
In 2002…the maximum temperature in Denver equaled or exceeded 90 degrees for 13 consecutive days…equaling the 5th longest such streak on record. The record of 18 consecutive days was set during the summer of 1901.
28
In 1873…there was a great deal of smoke over the city from forest fires in the mountains.
In 1875…smoke from forest fires in the foothills south of Denver were visible from the city.
In 1913…an apparent dry microburst produced southwest winds sustained to 44 mph with gusts to 48 mph in the city.
In 1925…a thunderstorm produced north winds sustained to 38 mph with gusts to 44 mph.
In 1958…a microburst caused a brief wind gust to 58 mph at Stapleton Airport.
In 1964…lightning struck several homes in metro Denver… Sparking fires. Some flooding occurred in the stockyards area…at West 45th Avenue and St. Paul Street…and along Harvard Gulch.
In 1997…strong microburst winds of unknown speed downed several trees…signs…and at least one light pole in the Fort Lupton area. Two trees knocked over by the storm downed power lines causing scattered outages.
In 2002…a thunderstorm wind gust to 60 mph was recorded in Parker.
In 2005…severe thunderstorms produced wind gusts to 66 mph near Longmont and to 60 mph near Niwot. No damage was reported. A thunderstorm produced a wind gust to 55 mph at Denver International Airport during the afternoon.
29
In 1874…eight different fires in mountain forests were visible from the city. All of the fires were extensive… And the volume of smoke from each was immense. Three of these fires had been burning from the 18th with varied intensity.
From the National Weather Service: June 2009 has moved into the second wettest June since Denver weather records began in 1872. So far for June 2009, through June 26th, the Denver International Airport (DIA) has measured 4.86 inches of liquid (and there are still 4 more days left in June). The 4.86 inches of water is 3.52 inches above normal through the 26th. Last year, June 2008 had only measured 0.73 inch again through the same June time frame.
The wettest June on record for Denver was in June 1882 when 4.96 inches of moisture was collected in the rain bucket.
For the 2009 year so far, 10.38 inches of water has been measured at DIA which is a very impressive 2.51 inches above the normal through June 26th. Last year in June, only 3.04 inches had been recorded through the same time frame.
Note: The average Denver annual precipitation is 15.81 inches.
June 21 to June 27 - This week in Denver weather history
A typical week during the spring and summer for Denver – tornadoes, hail, damaging winds and more.
19-21
In 1875…smoke from several large forest fires in the mountains was visible from the city on each of these days.
20-21 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.
21
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.
Something you will not see in Thornton - tornado sirens.
In yesterday’s Northglenn-Thornton Sentinel, the paper wrote about tornado sirens and warning systems in the north metro area – or rather the lack thereof. Appropriately titled “Sound of silence”, the article points out that Thornton is not alone in their lack of any sort of severe weather warning system.
Westminster, Northglenn, Federal Heights and Adams County leave citizens to fend for themselves as well. Brighton and Commerce City have siren systems to protect residents of their cities.
Emergency managers cited a number of reasons including the ever-present cost consideration and the fact that severe weather season in Colorado is relatively shortlived. It is the opinion of ThorntonWeather.com that these thoughts are all extremely shortsighted and cities are risking their citizens’ lives.
One of the more interesting sections of the article reflects that:
Mike Reddy, captain of emergency management for the Westminster Fire Department, said Mother Nature often provides enough warning for those people who are caught outside during severe weather.
“To me it’s like lightning. If you are out playing golf and there is lightning, it’s best to go inside where it’s safe,” Reddy said. “Tornado sirens are a very expensive investment that it turns out are used three weeks out of the year.
With all the media coverage and alternative approaches, there are more effective ways for people to be notified.”
Reddy added that the information he gets from dispatch about severe weather can be found on the local news channel or Internet.
Do tornadoes strike in the Denver area? 177 have been recorded in the metro area alone since 1950. They have occurred as early as April 10th and as late as October 14th. Map courtesy TornadoPaths.org.
Captain Reddy may wish to familiarize himself with the history of tornadoes in Colorado. Since 1950, tornadoes have been recorded as early as April 10th and as late as October 14th – in the Denver metro area alone. Further, through yesterday, 177 twisters have been recorded in the metro area during that same time frame so despite what some may say, they are not rare.
If a warning system saved your life or the lives of your family, wouldn’t it be worth it?
We recently wrote an article on Examiner.com detailing the current state of emergency warning system across the metro area. While we had similar results in our talks with various cities that the Sentinel did, we also found that many communities are taking advantage of lower-cost, high tech solutions that incorporate notifying residents of emergencies using email and text messaging. These types of systems have the added benefit of having multiple uses and can be used to notify residents about other significant events including Amber Alerts, wildfires, chemical spills, civil disasters and terrorist attacks.
We recognize that siren systems are expensive and limited in their reach. However, we applaud those communities that are taking steps using other methods and implore Thornton and other north metro area municipalities to do the same.
What do you think? Should north metro communities invest in emergency alert systems to protect their citizens? Leave a comment below with your thoughts!
Ominous clouds tinged by green appeared over Thornton on Sunday. More images of the severe weather are posted below.
What had been a relatively quiet Sunday was shattered by severe storms moving across the Denver metro area and Thornton on Sunday. A deluge of rain coupled with hail and funnel clouds sent Thornton residents scrambling for cover and caused a rain delay for the Colorado Rockies when a funnel cloud was spotted near Coors Field. Hail up to 1 1/2 inches fell in parts of Thornton.
New photos added – Funnel cloud near Coors Field. See below.
A Tornado Warning was issued for a large swath of the metro area including Thornton. The warning has since expired but a Tornado Watch remains in effect for Thornton until 9:00pm Sunday evening so residents should remain aware.
June 14 to June 20 - This week in Denver weather history
With severe weather season in full swing, we see a very eventful week in Denver weather history. Wildfires, amazing hail storms, tornadoes, floods and more all make an appearence on the historical calendar.
11-14
In 1999…damage from several hailstorms in and near metro Denver totaled 35 million dollars. About 17.5 million dollars was from automobile claims with another 17.5 million in homeowner claims. The areas hardest hit by the storms included Castle Rock…Commerce City…evergreen… And Golden.
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.
13-14
In 2006…the high temperature of 99 degrees on the 13th equaled the record maximum temperature for the date first set in 1994. The high temperature of 102 degrees on the 14th was a new record maximum temperature for the date.
14
In 1877…an evening thunderstorm produced lightning which struck several houses and killed a cow in the bottom land of the South Platte River
In 1886…hail as large as 3/4 inch in diameter fell in the city. Precipitation was only 0.10 inch.
In 1887…south winds were sustained to 41 mph.
In 1900…a thunderstorm produced northwest winds to 51 mph with gusts to 61 mph…but only a trace of rain.
In 1923…a severe thunderstorm pelted the city with hail. The stones ranged in diameter from 0.2 to 0.8 inch. Gardens and greenhouses suffered considerable damage. Rainfall was only 0.14 inch downtown.
In 1960…one workman was killed and 4 others injured in Lakewood when a partly built apartment building collapsed in strong winds. Microburst wind gusts to 54 mph caused some blowing dust at Stapleton Airport.
In 1967…tornadoes touched down briefly 3 miles west of Franktown and 4 miles northeast of Parker. No damage was reported. Numerous funnel clouds were reported over south metro Denver…one 5 miles south of Denver…one 2 to 3 miles north of Castle Rock…and two near Littleton.
In 1968…a microburst wind gust to 52 mph was recorded at Stapleton International Airport.
In 1972…1 3/4 inch hail was reported in Wheat Ridge.
In 1976…high winds…unusually strong for this late in the season…raked metro Denver. Wind gusts estimated to 100 mph tore 24 boats from their moorings and damaged a total of 47 boats at Boulder reservoir. Wind gusts to 82 mph were recorded in Boulder. The strong winds toppled the wind mast at a radio station in Boulder. An automobile was smashed by a fallen tree in Boulder. Other damage in Boulder was minor…but power outages occurred when tree limbs fell on power lines. At Jefferson County Airport near Broomfield…wind gusts to 78 mph were recorded with 87 mph gusts clocked at rocky flats nuclear plant south of Boulder. Wind gusts to 66 mph were observed in Littleton… And northwest winds gusted to 46 mph at Stapleton International Airport. The strong winds collapsed a barn near Arvada. Several horses received minor injuries. Thirty trees were uprooted or broken in Denver. Four major power outages occurred from west Denver and Lakewood to the foothills.
In 1982…the worst hailstorm in 17 years struck Commerce City. The storm left 4 to 8 inches of hail on the ground. A few of the stones were as large as golf balls. Many vehicles were dented…and some windshields were shattered. Roofs of homes were damaged. Total damage was estimated at over one million dollars. Hail to 1 inch in diameter also fell in Littleton. Only 1/4 inch hail was measured at Stapleton International Airport.
In 1988…lightning ripped a small hole in the roof of a home in the southern part of Boulder. There were some power outages in the area.
In 1992…an off duty national weather service employee reported hail to 1 inch diameter in Westminster.
In 1997…one inch diameter hail fell in Bennett…and 3/4 inch hail was measured in Littleton.
In 1999…hail as large as 1 1/2 inches in diameter hit Aurora. Lightning sparked two small fires at separate residences near the hiwan country club in evergreen.
In 2004…lightning sparked two small fires near Jamestown. One was in geer canyon and the other 7.5 miles up sunshine canyon. Both were quickly contained and caused no damage to structures in the area.
This funnel cloud was seen on Tuesday, June 9, from the Thornton Civic Center (looking north). Image courtesy Lisa Wilson, the City of Thornton.
MetroNorth Newspapers in the Northglenn-Thornton Sentinel covered the recent bout of severe weather in the most recent edition of Thornton’s hometown newspaper. In part, the article says:
As a former producer for 9News, Todd Barnes has chased a few tornadoes in his time. On Sunday, however, the storm found him.
Barnes, communications manager for the City of Thornton, was shopping at Costco in the Larkridge development near 162nd Avenue and Interstate 25 when he witnessed the funnel cloud form. The tornado touched down at 1:17 p.m. one mile north of Broomfield, near the northwestern edge of Thornton.
“There’s nothing like watching a tornado touch down,” Barnes said Monday. “It’s incredible.”
Another funnel cloud was spotted over the city at about 4:30 p.m. Tuesday. It appeared only briefly, high in the sky at a nearly 90-degree angle, before disappearing, according to witnesses. A tornado did touch down outside Firestone shortly after 5 p.m., but no serious damage was reported.
Do you subscribe to the Sentinel? Why not? There is no other source of truly local news available to Thornton and Northglenn residents and MetroNorth News and the Sentinel do an outstanding job of providing the depth of news and information area residents really need. If you haven’t read the Sentinel, pick up a copy and check it out. They do have a website but it isn’t particularly noteworthy and doesn’t have the same information you get in the print version. Subscriptions for the paper are very inexpensive and I would highly recommend it to everyone who lives in the area. Check it out and support Thornton’s hometown newspaper!
On June 3, 1981 a tornado struck Thornton in what is the worst twister to have struck the Denver metro area. Despite this, Thornton does not have any sort of emergency alert system to warn citizens of tornadoes or other civil disasters. Image courtesy the City of Thornton archives.
As we have discussed before, the City of Thornton is lacking any type of system to alert citizens of severe weather like we have seen recently. In the last week, parts of Thornton have been under Tornado Warnings as funnel clouds circled in the sky and citizens are understandably concerned.
We at ThorntonWeather.com continually remind people that the Denver metro area is at the far western edge of Tornado Alley and funnel clouds, tornadoes, hail and other types of severe weather are not unusual at all. It was 28 years ago last Wednesday in fact that the costliest tornado to ever hit the Denver metro area struck Thornton. Accounts vary but 53 people were injured, at least 25 homes were destroyed and hundreds more damaged.
The danger is real – tornadoes can and do strike in the Thornton area. In some ways it is surprising that the city did not implement some sort of system in the wake of the tornado in 1981. Many municipalities in the metro area do have warning sirens including Denver, Aurora, Englewood, Commerce City and Brighton.
Thornton Mayor Erik Hansen has told ThorntonWeather.com that the city will look at ways to inform citizens when severe weather is imminent. This may take the form of utilizing the reverse 911 system or as we suggested to him, a possible new text alert system that would deliver alerts to citizen’s mobile phones. It is our firm belief that some sort of system to be used not only for severe weather but for other civil disasters is a wise and prudent investment for the city to take.
The Denver area is at the western edge of Tornado Alley and as we have seen historically and in recent days, the danger is real. Click image for larger view. Image courtesy NOAA.
This week the city posted some tornado safety tips on its website that are worth reviewing. You may also wish to review our Severe Weather 101 series which provides more in depth information on the entire array of spring and summer severe weather (links below).
We will continue our conversations with the city about how they can improve communication with Thornton residents about severe weather and keep you updated as appropriate. If you are so inclined, contact your city council representatives and let them know you want to see Thornton implement an emergency alert system.
This funnel cloud was seen on Tuesday from the Thornton Civic Center (looking north). Image courtesy the City of Thornton.
Severe weather has returned to the Denver metro area and the Front Range Tuesday afternoon. At approximately 4:50pm and for nearly one half hour afterwards trained spotters reported numerous funnel clouds over the Northglenn, Thornton, and Broomfield areas. No tornadoes touched down however.
Do you have pictures of the severe weather? Email them info@thorntonweather.com and we will post them.
At 5:11pm local law enforcement reported a tornado four miles northwest of Firestone moving at 20mph. This area remains under a Tornado Warning until 5:00pm.
If you are in an area under a Tornado Warning, do not try to outrun the storm or chase it in your vehicle. Immediately seek shelter in a building. If no structure is available, seek shelter in a ditch or low spot. If in your home or other building go to an interior hallway or ideally the basement.
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Weather, natural disasters & climate news and information.
Change is of course the one constant in Denver’s weather but come July, things actually get pretty consistent. The standard formula for a day in July is a sunning morning, clouds developing in the late morning and early afternoon. Come mid-afternoon, thunderstorms are rolling off of the foothills and into the metro area and the eastern plains. These storms do occasionally reach severe status containing hail, gusty winds and heavy downpours of rain.
