All posts by Thornton Weather

ThorntonWeather.com is your local source for live Thornton, Colorado weather conditions and news!
Weather History

June 27 to July 3: This week in Denver weather history

Leave a comment

This Week in Denver Weather History

Closing out June and entering July our look back at this week in Denver weather history is marked by severe weather and scorching heat.  Damaging hail to dangerous lightning are two common occurrences as is record-setting heat waves.

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.

26-27

In 1965…wind gusts to 38 mph were recorded in downtown Boulder…causing widespread minor damage.  A microburst wind gust to 41 mph was recorded at Stapleton International Airport.

27

In 1873…Pikes Peak was hidden from view by smoke from forest fires in the mountains to the southwest of the city.

In 1927…the temperature cooled to a low of only 72 degrees… The all-time record high minimum for the month.

In 1980…lightning injured 4 people on a baseball diamond in Broomfield.  The bolt seriously injured the pitcher while also striking (out) the batter…catcher and second baseman.

In 1987…a microburst wind gust to 53 mph was recorded at Stapleton International Airport.

In 1990…the temperature reached a high of 102 degrees… Setting a new record maximum for the date.

In 1993…thunderstorm winds gusted to 60 mph across parts of metro Denver.  A wind gust to 50 mph blew over a 30-foot canvas tent at an amusement park southeast of Denver. Fifteen people…mostly children…were injured.  Microburst wind gusts to 33 mph were recorded at Stapleton International Airport.

In 2002…heavy rain…up to 3/4 inch…fell across sections of the Hayman burn area near Cheeseman Reservoir.  Several forest service roads were washed out and many culverts were plugged by debris.

In 2004…heavy rain producing thunderstorms caused rock and mud slides across the overland fire burn area in Jamestown. An estimated 50 tons of sand…dirt…rock…and ash slid into town…filling a culvert under main street.  The slide covered 150 to 225 feet of Main Street.  The flood was produced by half an inch of rain in 30 minutes.  A deluge of very heavy rainfall from nearly stationary thunderstorms caused flooding and flash flooding problems over parts of Jefferson and Douglas counties.  An automated rain gage in Golden measured 3.60 inches of rainfall in one hour.  Numerous homes were flooded in Golden…including one that was 146 years old. The home was listed as a complete loss.  State Highway 93 had to be closed from the Pine Ridge subdivision to the Golden Gate Canyon Road.   At the height of the storm…about 4 feet of water covered State Highway 93 through Golden… Forcing its temporary closure.  Several intersections were also flooded and impassable.  Rock and mud slides were reported in Golden Gate Canyon State Park.  At the Deer Creek Golf Course at Colorado 470 and Kipling…the greens were completely inundated by floodwaters.  Some backyards near the golf course were partially washed out.  In Douglas County…water up to a foot deep covered the roadways in Roxborough State Park.  The Waterton Canyon Road also had to be closed due to high water.

In 2010…a severe thunderstorm produced hail up to 1 inch in diameter near Strasburg. Hail up to 3/4 inch in diameter was reported in Aurora and Buckley Air Field.

In 2014…a severe thunderstorm produced hail…up to 1 inch in diameter…near Ft. Lupton.

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.

In 2015…a lightning strike injured 15 hikers as they were descending 500 feet below the summit of Mt Bierstadt…in Clear Creek County…south of Georgetown. Eight adults were were transported from the trailhead…and three of those were taken to Denver-area hospitals. One was in serious condition…the other two had non-life threatening injuries. The strike also killed a dog. Severe thunderstorms produced hail up to 1 1/2 inches in diameter…7 miles southwest of Byers…and 1 1/4 inches in diameter…13 miles north of Elizabeth.

In 2016…severe thunderstorms produced hail…from quarter to ping ball size…over northwest…west and southwest parts of Denver. In addition hail up to quarter size was also reported just southeast of Denver International Airport. Officially only a trace of rainfall was measured at the airport…with a peak wind gust of 35 mph from the west.

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.

In 1911…an apparent dry microburst produced sustained winds to 45 mph.

In 1960…a strong gust of wind blew a small foreign sedan off the highway near Brighton…injuring the driver.  East winds gusted to 40 mph at Stapleton Airport.

In 1961…thunderstorm winds estimated as high as 40 to 50 mph occurred over southeast Denver.  No significant damage was reported.

In 1962…heavy rain and small hail caused some flooding in southwest Denver.

In 1995…upslope cloudiness with rain and fog cooled temperatures to record levels.  Low temperature of 47 degrees equaled the record for the date.  High temperature of only 54 degrees set a new record low maximum for the date.  Rainfall totaled 0.90 inch at Denver International Airport and 0.41 inch at the site of the former Stapleton International Airport.

In 2003…a severe thunderstorm in Parker produced hail to 1 inch in diameter.

In 2011…two airmen from the Colorado National Guard suffered minor injuries when they were struck by lightning. They were hit while on duty at a flight line at Buckley Air Force Base. At Denver International Airport…a microburst produced a peak wind gust to 72 mph.

29-2

In 1990…almost a year to date after the record breaking heat in early July 1989…the third longest heat wave in Denver history started.  From June 29th through July 2nd the temperature reached 100 degrees or more on four consecutive days.  The highest reading of 102 degrees occurred on the 29th…30th…and 1st.  Combined with the 102 degree reading on June 27th this would have been the longest heat wave on record…but the temperature climbed to only 98 degrees on June 28th.

29-15

In 2000…the 29th marked the beginning of a near record hot streak for metro Denver.  The high temperatures…as recorded at Denver International Airport…exceeded the 90 degree mark for 17 consecutive days from June 29th through July 15th. This was one day short of equaling the all time record.  The record of 18 consecutive 90 degree or above days was first set from July 1st through July 18th…1874.  The record was equaled from July 6th through July 23rd…1901.

Continue reading June 27 to July 3: This week in Denver weather history →

Photography, Thornton Weather

June 2021 top shots: Monthly photo slideshow

Leave a comment
A landspout tornado touches down between Firestone and Platteville on June 7, 2021. (Brigette Rodriguez)
A landspout tornado touches down between Firestone and Platteville on June 7, 2021. (Brigette Rodriguez)

The month of June typically sees springtime severe weather reach its height of activity in northeastern Colorado.

This affords the opportunity to capture extraordinary images of amazing weather phenomena from monstrous supercell thunderstorms to heavy rain, hail and even tornadoes.

  • Slideshow updated June 29, 2021

Showcasing images captured by ThorntonWeather.com readers as well as some of our own, our monthly slideshow covers the entire gamut of weather and nature related imagery.

Sunsets, sunrises, wildlife and of course every type of weather condition are vividly depicted.  June brings some very dynamic weather and the photos are a great way to see the stunning variety.

To learn more about how to send your photo to us for inclusion in the slideshow, see below the slideshow.

[flickr_set id=”72157719376583098″]

What is missing in the slideshow above?  Your photo!

Our monthly photo slideshow is going to feature images that we have taken but more importantly images that you have captured.  The photos can be of anything even remotely weather-related.

Landscapes, current conditions, wildlife, pets, kids.  Whimsical, newsy, artsy.  Taken at the zoo, some other area attraction, a local park, a national park or your backyard.  You name it, we want to see and share it!

Images can be taken in Thornton, Denver or anywhere across the extraordinary Centennial State.  We’ll even take some from out of state if we can tie it to Colorado somehow.

We’ll keep the criteria very open to interpretation with just about any image eligible to be shown in our slideshows.

What do you win for having your image in our slideshow?  We are just a ‘mom and pop’ outfit and make no money from our site so we really don’t have the means to provide prizes.  However you will have our undying gratitude and the satisfaction that your images are shared on the most popular website in Thornton.

To share you images with us and get them included in the slideshow just email them to us or share them with ThorntonWeather.com on any of the various social media outlets.  Links are provided below.

So come on, get those camera’s rolling!

Weather Education

Lightning and wildfires – Hand in hand hazards

Leave a comment
Wildfires and lightning go hand in hand as half of Colorado’s blazes are ignited by lightning.

Wildfires are not strictly a weather-related threat.  The weather does however play a significant role in starting fires and in the ability of firefighters to battle them.

From the National Weather Service:

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
500 PM MDT SAT JUNE 26 2021

Colorado Lightning Safety Week concludes today…with wildfires being the final topic.

During the past week we have presented lightning information and safety rules.  Although wildfires are not an actual weather phenomenon…wildfires are directly related to lightning and other weather elements.

Normally…the wildfire threat in Colorado increases significantly after the middle of June and usually peaks in early July…and remains high through august and early September.  Colorado averages about 2500 wildfires each year.

About half of all forest fires in Colorado are ignited by lightning. Additionally…many rangeland and wheat field fires are caused by lightning. Many of these lightning caused wildfires occur in the absence of rain and are the result of what is referred to as dry thunderstorms.

Lightning is often accompanied by strong winds from thunderstorms. These winds can quickly turn smoldering organic material into a raging fire.  Thunderstorm winds tend to be erratic in direction and speed…posing one of the greatest dangers for firefighters.

Lightning that strikes the ground is usually divided into two categories…negative and positive strikes… Depending on the ionic source region of the thunderstorm.  The negative strikes are far more common than positive strikes.  The positive strikes are more intense and have a longer duration than the negative strikes and are more likely to ignite a fire.  Lightning detection technology provides land managers and weather forecasters with the ability to identify the general location and charge category of each lightning strike.

National Weather Service forecasters help land managers and firefighters by producing fire weather zone forecasts on a daily basis.  Spot fire weather forecasts are also provided for those who work on prescribed burns or specific wildfires.  Forecasters also issue red flag warnings for use by land managers when the combination of dry vegetation and critical weather conditions will result in a high potential for the development and spread of

Wildfires.  Land managers…in turn… Typically inform the general public of the fire danger in national parks…forests… And other public lands.

During periods of extreme fire danger in forests and rangelands…

  • You should avoid being in areas where you might become trapped by a wildfire.
  • You should avoid the use of matches or anything else which could ignite a fire.
  • Make sure that hot parts of motorized equipment…such as mufflers…are not allowed to come in contact with dry grasses or other potentially flammable material.
  • If you become trapped or cut off by a wildfire seek shelter in areas with little or no fuel…such as rock slide areas or lakes.

For more information on wildfires and fire safety…please check out the following web addresses…

Lightning Safety and Wildfire Awareness Series:

Weather Education

When lightning strikes – Rendering aid and the lasting effects of a strike

Leave a comment
Lightning strike (NOAA)
Responding quickly to lightning strike victims is key to helping them survive. (NOAA)

Knowing what to do when lightning strikes someone is critical to helping them survive.  As with many serious injuries, immediate action must be taken.  After the event, lightning strike victims oftentimes face a number of health and mental challenges.

From the National Weather Service:

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE BOULDER CO
600 AM MDT FRI Jun 25 2021

Colorado Lightning Safety Awareness Week continues through tomorrow. Today we discuss lightning medical issues for survivors.

The facts about lightning strike victims:

In Colorado, nearly a half million cloud-to-ground lightning flashes are documented each year. With millions of visitors and extensive outdoor activities, it is not surprising that, each year on average, three people are killed by lightning in the state of Colorado while 13 are injured. Last year, two people were killed by lightning in the Centennial State while seven were injured.

While any lightning fatality is tragic, injuries caused by lightning can be devastating to both the victim and the family. For those who have a family member or relative that suffers a significant disability from lightning, life changes forever. In addition to the physical pain and mental anguish suffered by the victim and their family, the incident may lead to a loss of income for all involved as medical expenses can drain the family’s financial resources.

If someone is struck by lightning, it is critically important that they receive the appropriate medical attention immediately. Some deaths can be prevented if the victims are attended to promptly. Lightning victims do not carry an electrical charge and are safe to handle. First, check to see that the victim is breathing and has a pulse, and start cardio-pulmonary resuscitation, if needed. Then have someone dial 911. If possible, move the victim to a safer place. Do not let the rescuers become lightning victims. Lightning can strike the same place twice.

Lightning strike victims may face many mental challenges that they will have to live with for the rest of their lives. When the brain is affected by a lightning strike, the person often has difficulty with many of the mental processes that most people take for granted. The person may suffer from short-term memory loss, and may have difficulty remembering new information and accessing old information. Victims may often find it very difficult to carry on more than one task at a time, and may be easily distracted. Their personality may change and they may become easily irritated.

Lightning strike victims often become easily fatigued and may become exhausted after only a few hours of work. This may be because mental tasks that were once automatic may now require intense concentration to accomplish. Although some victims may sleep excessively at first, after a few weeks many find it difficult to sleep more than two or three hours at a time.

Another common long-term problem for survivors is pain.

Medically, pain is difficult to quantify. Lightning strike victims often suffer irreparable nerve damage that causes intense pain that affects the ability to function. Many survivors complain of chronic headaches, some of which are very intense and debilitating.

Lightning Strike and Electric Shock Survivors International is a support group for individuals and families that are struggling with life after a lightning injury. Helpful information is available at their web address: www.lightning-strike.org

In addition, NOAA’s lightning website contains abundant information on lightning safety and can be found at: www.lightningsafety.noaa.gov

Lightning information specific for the State of Colorado can be found at: www.weather.gov/pub/lightning

The lightning topic for tomorrow will be lightning caused fires.

Lightning Safety and Wildfire Awareness Series:

Weather Education

Indoor lightning safety – Staying safe in your home or office

Leave a comment
Lightning can cause injury and even death indoors. (Wikipedia)

Certainly the dangers of lightning are most prevalent outdoors and being indoors is the safest place to be when thunder is heard. Even inside your home or business lightning can be damaging and cause significant injury.

From the National Weather Service:

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE GOODLAND KS
600 AM MDT THU JUN 24 2021

Statistics tell us that we are much less likely to become a lightning strike victim if we are inside a substantial structure such as a home or office building. In 2016, thirty eight people in the United States were killed by lightning, and all of these fatalities occurred outdoors. While nearly all people who are injured or killed by lightning were outdoors, a small percentage of people are injured by lightning while indoors. Therefore, it is important to discuss lightning safety while indoors.

The dangerous electrical current associated with a lightning strike typically enters a structure through wires, cables or pipes that connect to the building from the outside. Lightning can also directly enter into a structure through an open window, door or garage door. Once in a structure, the dangerous current can travel through the electrical, phone, cable and plumbing systems and through metal wires or bars in concrete walls or flooring.

Corded electronic devices are the leading cause of indoor lightning injuries in the United States. These include personal computer keyboards, game consoles, and corded phones. Other injuries have occurred when people were close by to televisions which connect to an outside cable or satellite system. Open windows, doors and garage doors allow for a direct strike to enter a home, so make sure all windows and doors are closed when lightning is occurring. Never watch a lightning storm from a porch or open garage door. There are several You-Tube videos that show people being injured by lightning while they were recording lightning from their porch or open garage door.

It is very important to stay away from any plumbing when lightning is occurring outside. This includes sinks, bathtubs and showers. When lightning is occurring, do not hand wash dishes, do not give kids a bath, and do not take a shower. It is best to wait to do laundry until after the storm goes by as washers and dryers are connected to both the electrical and plumbing systems.

People have also been injured while leaning and standing near concrete in their homes and offices. This is due to metal rebar which is in the concrete, and this metal acts as a conductor when lightning hits the building.

A house or other substantial building offers the best protection from lightning. In contrast, many small shelters such as bullpens, picnic shelters, sheds or tents (no matter what the size) offer no protection from lightning, and should be avoided at all cost.

Here is a summary of lightning safety tips for inside the home:

1. Avoid corded electronics and electrical equipment.
2. Avoid contact with plumbing, such as taking a shower, bathing, hand washing dishes or doing laundry.
3. Stay away from windows, doors, garages and porches.
4. Do not lie on concrete floors or lean against concrete walls.
5. If a substantial building is not nearby, an enclosed car or truck offers excellent protection from lightning.

Below are a couple of web sites that contain additional lightning information:

NOAA’s lightning website which contains abundant information on lightning safety can be found at: www.lightningsafety.noaa.gov

Lightning information specific for the State of Colorado can be found at: www.weather.gov/pub/lightning

The lightning topic for tomorrow will be lightning medical issues for survivors.

Lightning Safety and Wildfire Awareness Series:

Weather Education

Outdoor lightning safety – When thunder roars, go indoors

Leave a comment
When Thunder Roars, Go Indoors - Lightning Safety Poster (NOAA)
One simple phrase provides the most important safety tip for lightning – When Thunder Roars, Go Indoors. (NOAA)

Statistics provide insight into the dangers of severe weather and lightning is one of the most deadly.  Over the past decade Colorado has been the second deadliest state for lightning and many of these fatalities could have been avoided if the victims had remembered one key phrase: When thunder roars, go indoors.

From the National Weather Service:

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
600 AM MDT WED JUNE 23 2021

Colorado Lightning Safety Awareness Week continues through Saturday. Yesterday we discussed the science of lightning. Today we will cover outdoor lightning safety.

Outdoors is the most dangerous place to be during a thunderstorm.

Each year…nearly all people in the United States who are injured or killed by lightning were involved in an outdoor activity. They were struck while working outside…were at or participating at an outdoor sporting event…were boating or fishing. They were struck while hiking…mowing the lawn or simply going to or from their car.   Quite a few were on their own property when they were struck.

Unfortunately…there is no place outside that is safe from lightning. The only safe place to be when lightning is occurring is either inside a substantial building…or an enclosed automobile.

Here are some important things to remember before venturing outdoors…

An informed decision will help you avoid being in an area where lightning is expected to occur.  Before heading out…get an updated forecast. Stay tuned to NOAA weather radio…check national weather service web sites…or access your favorite weather apps on your cell phone for the latest forecast.

In Colorado…it is important to remember that thunderstorms typically develop in the mountains after 11 am.  So it is best to plan your climbing or hiking trip so that you are coming down the mountain by late morning.

If thunderstorms are in the forecast…consider planning an alternate indoor activity or make plans which will allow you to quickly get into a safe shelter.

Once you are outside…keep up-to-date on the weather via your smart phone or portable NOAA weather radio receiver. Check for updated forecasts. Check if storms are near you by checking the latest radar imagery on your cell phone. There are now several smart phone apps you can purchase that show you real-time lightning activity in your area. Do not forget to simply look around you to make sure storms are not developing in your vicinity.

We will now discuss two outdoor scenarios. The first is what to do if you are outdoors and a safe location is nearby…while the second scenario is what to do if you are outdoors and no safe location is nearby.

If you are outside…such as a park…a lake…or an outdoor sporting event…know where the nearest safe location is located at.

A safe location is any substantial building…such as a business…a home…or a church. Any enclosed hard topped automobile also offers excellent protection from lightning. Once you hear thunder or see lightning…immediately stop what you are doing and quickly get to the safe shelter. Do not wait until the rain starts to seek safe shelter. Once inside a safe shelter…it is recommended you stay there for 30 minutes after the last rumble of thunder.

Past history has shown that most people who were outdoors and were injured or killed by lightning had access to a safe shelter nearby.

Do not wait to seek safe shelter when lightning threatens. When you hear thunder or see lightning…it is important for you…and your family…to act quickly.

It is critically important to avoid shelters that are not safe from lightning…including picnic shelters…bullpens…tents and any other small buildings that are open to the elements.

Never…never…get under a tree to seek shelter from lightning.

It is important that all sports leagues and other outdoor groups have a lightning response plan that is understood and consistently applied for the safety of the participants. Part of the plan would include a designated weather watcher at each outdoor event with the authority to postpone or cancel the event due to the threat of lightning. It is also important that people know where to seek safe shelter if a storm threatens. As we have seen recently…the NCAA…the NFL and MLB now delay games when lightning is in the area.

Our second scenario involves what you can do to reduce your chances of being injured or killed by lighting if no safe shelter is nearby.

This situation typically occurs to people who are hiking or camping in the backcountry. Unfortunately…in this scenario…there is not much you can do to reduce your risk from being struck by lightning.

The best thing to do is move away from tall isolated objects…such as trees. Stay away from wide open areas. Stay as low as possible with your feet close together if lightning is nearby. If you are with a group of people…spread out…that way if someone is struck by lightning…the others can offer first aid. If camping in the backcountry…place your tent in a low area away from tall isolated trees.

Remember…when thunder roars…go indoors!

There are a couple of web sites that contain additional lightning information.

NOAA’s lightning website which contains abundant information on lightning safety can be found at…

WWW.LIGHTNINGSAFETY.NOAA.GOV

Lightning information specific for the state of Colorado can be found at…

WWW.WEATHER.GOV/PUB/LIGHTNING

The lightning topic for tomorrow will be on indoor lightning safety.

Lightning Safety and Wildfire Awareness Series:

Weather Education

The science of thunderstorms and lightning

Leave a comment
Lightning produced by thunderstorms presents a very real danger to Colorado residents. Image courtesy VORTEX2 / NSSL.

Thunderstorms and their associated hazards frequently make appearances in Colorado during the spring and summer months.  Lightning presents one of the damaging – and deadly – aspects of these storms and knowing more about the science behind the phenomena helps us to better protect ourselves.

As part of Lightning and Wildfire Safety Awareness Week, this installment from the National Weather Service gives more information on the science behind these bolts of electricity.

From the National Weather Service:

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE BOULDER CO
600 AM MDT TUE Jun 22 2021

…UNDERSTANDING THE SCIENCE OF THUNDERSTORMS AND LIGHTNING…

Every thunderstorm produces lightning. Lightning is a giant spark that moves within the cloud…between clouds…or between the cloud and the ground. As lightning passes through the air…it heats the air rapidly to a temperature of about fifty thousand degrees Fahrenheit. This causes a rapid expansion of the air near the lightning channel. This rapid expansion causes a shock wave that we hear as thunder.

Thunderstorms will form if there is enough moisture and instability in the atmosphere. As the sun warms the air near the ground…pockets of warmer air begin to rise and cool. Condensation of water vapor causes cumulus clouds to form. Continued heating can cause these clouds to continue to grow upward into the atmosphere. Towering cumulus clouds may be one of the first indications of a developing thunderstorm. The mature thunderstorm has both an updraft of rising motion and a downdraft of sinking cool air accompanied by rain and sometimes hail.

Thunderstorms grow tens of thousands of feet into the atmosphere. In the cloud…precipitation forms as ice crystals…hail…and rain. Collisions between ice particles cause a charge separation…and positively charged ice crystals are carried by the updraft high in the thunderstorm. The heavier hail gathers a negative charge and falls toward the lower part of the storm. The top of the cloud becomes positively charged and the lower part of the storm becomes negatively charged.

Due to the pool of negative charges in the lower part of the storm…a pool of positive charges will develop along the ground and follow the cloud like a shadow. Farther away from the cloud base…but under the positively charged anvil…a strong negative charge may be induced.

Cloud-to-ground lightning can either be a negatively charged flash or a positively charged flash. The negative flash usually occurs between the negative charges in the lower part of the storm and the positive charges on the ground under and near the cloud base. Positive flashes usually occur between the positively-charged upper levels of the storm and the negatively-charged area surrounding the storm.

In the negative cloud-to-ground flash…an invisible…negatively-charged step leader forms near the cloud base and surges downward toward the ground. As this step leader approaches the ground… streamers of positive charge move upward from trees…buildings…and other objects on the ground. When these streamers meet the step leader…the connection is completed…and the result is lightning. The entire process takes place in fractions of a second.

If you are under a thunderstorm and your hair rises…you are in an area where the positive charges are rising up objects towards the storm. It is a dangerous location…because lightning may be about to strike.

The process for a positive flash is similar except that a positive channel usually originates in the anvil of the storm and surges downward. In this case…streamers of negative charge shoot up to meet the positively-charged channel as it approaches the ground. When a connection is made…a positive flash of lightning occurs.

While both negative and positive flashes of lightning can be deadly…the positive flashes generally are more destructive as they typically deliver more overall electrical charge to the ground…and they remain in contact with the ground surface for a longer period of time as compared to a negative cloud-to-ground flash.

The best advice in order to minimize your risk of becoming a lightning strike victim is to get indoors into a substantial shelter the second you hear thunder…and to remain there for at least 30 minutes after the last rumble of thunder.  In general…when thunder roars…go indoors. An enclosed hard topped automobile is also a safe place to be during thunderstorms.

For additional information about lightning or lightning safety…visit NOAA’s Lightning Safety Awareness web site at (in lower case):

http://www.lightningsafety.noaa.gov

Lightning Safety and Wildfire Awareness Series:

Colorado Weather, Thornton Weather, Weather Education

Lightning and wildfire safety overview

Leave a comment
Lightning fatalities by state, 1959-2007. (Vaisala)
Lightning fatalities by state, 1959-2007. (Vaisala)

Colorado has the rather unenviable distinction of ranking fourth in the United States for lightning-related fatalities.  During the spring and summer the nice weather finds many residents outside and while clear skies are the norm, storms oftentimes loom and present a very real hazard to residents.

From the National Weather Service:

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE PUEBLO CO
600 AM MDT MON JUN 21 2021

Colorado Lightning Safety Awareness Week continues through Saturday. Today we discuss the lightning threat across the Centennial State.

In the United States, there are an estimated 25 million cloud-to-ground lightning flashes per year, and each one is a potential threat to both life and property. During the past thirty years, 44 people have been killed each year by lightning on average, while during the last ten years this number is 27. Last year, 16 people were killed by lightning, while many others were injured. All of the people who were killed by lightning in 2017 were involved in outdoor activities.

In Colorado last year, lightning killed 2 people and injured 2. During the past thirty seven years, on average, Colorado has had 3 lightning fatalities and 12 injuries per year.

Since 1980, El Paso County, including the Colorado Springs metro area, has had the dubious distinction of having the most lightning casualties, with 10 fatalities and 84 injuries. Larimer County has had 10 fatalities and 75 injuries, while Jefferson County has had 9 fatalities and 38 injuries.

Because it usually affects one or two victims at a time, and does not cause the destruction left in the wake of tornadoes or hurricanes, lightning generally receives less attention.

Many people do not act in a timely manner to protect their lives, and the lives of others, simply because they do not understand all the dangers associated with thunderstorms and lightning.

You need to become aware of the situations that put you at a greater risk of being struck by lightning, and what you can do to reduce that risk. While nearly all people take some protective actions when rain, hail and wind are occurring with thunderstorms, many leave themselves vulnerable to being struck by lightning as thunderstorms approach, move overhead and move away.

Lightning can strike more than 10 miles from the rain area of a thunderstorm. That distance is about as far as you can hear thunder. If you can hear thunder, you could be in danger of being struck by lightning. When Thunder Roars, Go Indoors!

Most lightning deaths and injuries in Colorado occur during the afternoon when lightning is most likely to develop, and when people are more likely to be outside. Quite a few lightning fatalities occur when little or no rain is falling.

The chance that you will be struck by lightning in the United States is about 1 in 960 thousand for each year of your life. However, your chance of being struck will depend on whether you consistently practice all the lightning safety rules.

Lightning starts around half of the forest and rangeland wildfires across the state. Colorado averages around 2500 wildfires each year. Many of these lightning caused fires occur with very little or no rain. These storms often generate gusty winds, which can fan the flames of the fire.

During this Lightning Safety Awareness Week, the National Weather Service will provide a variety of information on lightning in Colorado.

On Tuesday, the science of lightning will be discussed.

On Wednesday, the topic of the day is outdoor lightning risk reduction. On Thursday, we will have information on indoor lightning safety.

On Friday, information for lightning strike survivors will be provided. On Saturday, lightning and wildfire information will be available.

When planning outdoor activities, check out the hazardous weather outlook and the latest forecast, which include thunderstorm and lightning potential. Make sure you get the specific forecast information of the location you will be visiting. The web sites for National Weather Service offices which cover Colorado and issue these products are…

Denver/Boulder…www.weather.gov/den Grand Junction….www.weather.gov/gjt Pueblo……………www.weather.gov/pub Goodland…………www.weather.gov/gld

NOAA’s lightning website which contains abundant information on lightning safety can be found at:

www.lightningsafety.noaa.gov

Lightning information specific for the State of Colorado can be found at: www.weather.gov/pub/lightning

The lightning topic for tomorrow will be the science of lightning.

 

Lightning Safety and Wildfire Awareness Series:

Thornton Weather, Weather Education

Lightning Safety and Wildfire Awareness Week highlights real dangers for residents

Leave a comment
Lightning Warning Sign - When Thunder Roars, Go Indoors
Protecting yourself and your family from the dangers of lightning can be summed up in one phrase: When Thunder Roars, Go Indoors

Colorado is starting its annual Lightning Safety and Wildfire Awareness Week, an important opportunity to educate residents of the dangers lightning presents.  One statistic serves to highlight the very real hazard of lightning in Colorado – the Centennial State ranks as the second deadliest state for lightning fatalities in the nation.

We oftentimes read about the results of lightning strikes in our weekly look at Denver weather history.  They spark wildfires, cause property damage and injuries and in some cases result in death.  From 2001 to 2010 26 people were killed by lightning in Colorado – second only to Florida.

Each day during the National Weather Service’s Lightning Safety and Wildfire Awareness Week a new message is publicized covering a range of topics.  From lightning safety to the science of lightning, residents can learn more about this very real danger.

The following is the introductory message from the National Weather Service for this year with links to more information.  Education is key to protecting you and your family and we encourage you to study these pages and remember – When Thunder Roars, Go Indoors!

From the National Weather Service:

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE BOULDER CO
600 AM MDT Sun Jun 24 2021

The governor of Colorado has declared the week of June 24 through June 30 as Colorado Lightning Safety Awareness Week. Lightning strikes the ground in our state over a half million times each year and with many of us participating in outdoor activities, we need to learn how to protect ourselves from lightning hazards.

Lightning is also responsible for about half of the wildfires in Colorado each year. When lightning or other conditions are conducive to a high wildfire threat, the National Weather Service will issue Fire Weather Watches or Red Flag Warnings.

During this week a series of statements will cover a variety of topics related to lightning and wildfires.

Monday…Lightning Overview for Colorado
Tuesday…The Science of Lightning
Wednesday…Outdoor lightning safety
Thursday…Indoor lightning safety
Friday…Lightning medical issues for survivors
Saturday…Lightning and wildfires

Here are a couple web sites that contain additional lightning information.

NOAA`s lightning website which contains abundant information on lightning safety can be found at:  www.lightningsafety.noaa.gov

Lightning information specific for the State of Colorado can be found at: www.weather.gov/pub/lightning

Steve Hodanish
Senior Forecaster
NWS Pueblo, CO

Weather History

June 20 to June 26: This week in Denver weather history

Leave a comment

This Week in Denver Weather History

Late June weather is usually relatively calm but when it turns severe, it can do so in spades.  Hail, flooding rains, tornadoes and more are not unusual.  This week in Denver weather history we see plenty of each of those including a hail storm in 1993 that damaged dozens of planes at Denver International Airport.

19-21

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

20

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.

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.

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 Airport. 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.

Continue reading June 20 to June 26: This week in Denver weather history →