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April 17 to April 23: This week in Denver weather history

April 17, 2022 Thornton Weather Leave a comment

As we enter the latter half of April the weather history calendar starts to reflect shift in the type of weather events we see. There are still plenty of significant snowfall events. However spring severe weather starts to appear with greater frequency including heavy rain, hail and even tornadoes.

From the National Weather Service:

13-17

In 2001…a huge dust storm over southern and Inner Mongolia during April 3rd through the 6th lifted desert dust into the jet stream. This dust cloud moved over metro Denver on the 13th and persisted through the 17th. The cloud created widespread haze…giving the sky a milkish cast due to the scattering of incoming solar radiation.

15-17

In 1922…heavy snowfall totaled 9.0 inches in downtown Denver. Most of the snow…6.0 inches…fell on the 16th. This was the third major snow storm in a week. Northwest winds were sustained to 43 mph with gusts to 47 mph on the 15th.

In 2016…a powerful spring snowstorm brought heavy…wet snow to areas in and near the Front Range Foothills and Palmer Divide. Storm totals generally ranged from 2 to 4 feet in the foothills with 1 to 2 feet in the mountain west of Denver and along the Palmer Divide. Along the I-25 Corridor storm totals ranged from 6 to 20 inches…with highest amounts across the western and southern suburbs. Some of those totals included: 16 inches in Aurora and Superior; 15 inches at the National Weather Service Office in Boulder; 14.5 inches in Broomfield; 13.5 inches in Westminster; officially 12.1 inches at Denver International Airport; 12 inches in Louisville; 11.5 inches in Arvada; 11 inches near Englewood; 10.5 inches near Wheat Ridge. At Denver International Airport…there were 852 flight cancellations… most of which occurred on the 16th. The heavy wet snowfall broke trees limbs and caused scattered power outages. Over five thousand customers were without power on the 16th…and over two thousand on the 17th. Xcel Energy brought in extra crews from surrounding states to help restore power and minimize outage times through the storm. Numerous but mostly temporary road closures from 1 to 5 hours occurred throughout the storm. This included portions of I-70 east and west of Denver…Highway 103 from Idaho Springs to Evergreen and Highway 119 through Black Hawk.

16-17

In 1944…heavy snowfall totaled 7.5 inches in downtown Denver. Northwest winds were sustained to 18 mph on the 16th.

16-18

In 2009…a potent spring storm brought heavy snow to locations in and near the Front Range foothills. A deep easterly upslope produced nearly 5 feet of snow in parts of the foothills. The heavy snow resulted in the closure of Interstate 70…from Golden west to Vail…for approximately 16 hours. The heavy snow snapped power lines in Evergreen and Nederland. The ensuing outages affected 14200 residents. In the Front Range foothills…storm totals included: 56 inches…3 miles south of Rollinsville; 54 inches…3 miles southeast of Pinecliffe…43 inches at Aspen Springs…42 inches at Evergreen…38 inches near conifer; 37 inches at St. Mary’s glacier…and 34 inches near Nederland. Along the urban corridor and Palmer Divide…the heaviest snow occurred above 5500 feet on the 17th. Storm totals included: 22 inches…8.5 miles southwest of Franktown; 18 inches…10 miles south-southeast of Buckley Air Force Base; 17 inches near Cherry Creek and 7 miles south of Sedalia… 16 inches…6.5 miles southwest of Castle Rock; 15 inches near Beverly Hills; 12 inches near Highlands Ranch and Lafayette…with 11 inches in Broomfield. Elsewhere storm totals ranged from 4 to 10 inches. Officially…only 2.6 inches of snow was observed at Denver International Airport. The 24-hr precipitation for the day however was 1.16 inches… Which established a new record for April 17th.

In 1889…northwest winds were sustained to 48 mph.

In 1899…apparent post-frontal north winds were sustained to 42 mph with gusts as high as 48 mph.

In 1935…light dust moved over the city behind an apparent dry cold front…which produced northeast winds to 19 mph with gusts to 20 mph.

In 1978…winds estimated to 70 mph occurred in Morrison. Northwest winds gusted to 49 mph at Stapleton International Airport.

In 2000…strong pre-frontal winds and widely scattered thunderstorms caused high winds to develop across northern metro Denver and portions of the northeast plains. Peak wind gusts included 75 mph at Louisville. South winds gusted to only 28 mph at Denver International Airport.

In 2002…strong southwest winds in advance of a cold front gusted to 52 mph at Denver International Airport.

In 2003…severe thunderstorms produced 1 inch diameter hail 7 miles east of Brighton. Strong thunderstorm winds blew out an auto windshield near Denver International Airport where south winds gusted to 48 mph.

17-18

In 1878…the wind blew violently all day on the 17th with a maximum sustained velocity of 40 mph. Dust hung over the city like a cloud. The relative humidity was zero nearly all day. A terrific gale blew overnight. There was much damage to buildings…signs…fences…etc. Some wind gusts were so strong as to jar buildings to their foundations. The station anemometer recorded sustained winds to 50 mph with higher gusts before it was damaged by the winds. The winds moderated during the day on the 18th and ended at sunset.

In 1894…post-frontal rain changed to snow on the 17th around sunrise and continued through 9:00 am on the 18th. Snowfall totaled 10.5 inches…but most of the snow melted as it fell. The high temperature warmed to only 35 degrees on the 17th after a high of 76 on the 16th. Northeast winds were sustained to 30 mph with gusts to 32 mph on the 17th.

In 1998…more spring snow fell across metro Denver and in the foothills. Snowfall totals included: 11 inches at Golden Gate Canyon; 10 inches at Highlands Ranch; 9 inches at Elizabeth; 8 inches at Broomfield and Morrison; and 7 inches at Chief Hosa…Evergreen…Littleton…and Sedalia. Snowfall totaled only 3.2 inches at the site of the former Stapleton International Airport. North winds gusted to 22 mph at Denver International Airport.

17-19

In 1920…snow fell across the city continuously for 57 hours… From the early morning of the 17th until 11:40 am on the 19th. The heavy wet snowfall totaled 18.2 inches with the greatest accumulation on the ground of 12 inches. Winds during the storm were strong with sustained speeds in excess of 27 mph for over 40 consecutive hours…which created near-blizzard conditions. The highest recorded wind speeds were 44 mph with gusts to 50 mph from the north on the 17th and 39 mph with gusts to 48 mph from the northwest on the 18th. The strong winds piled the snow into high drifts which stopped all Denver traffic. Railroads were blocked with only one train entering the city on the 19th. All interurban trains were blocked…as were the 13 trolley lines. Thus…many workers were unable to get home at night and filled all of the downtown hotels to capacity. No grocery or fuel deliveries were possible… Except milk and coal to hospitals and to families with babies. No lives were lost in the city…but several people perished in surrounding districts. Stock losses were heavy on the plains. Temperatures during the storm were in the 20’s.

In 1877…strong winds blew all day with an average sustained velocity of 36 mph. The maximum sustained velocity was 60 mph. No significant damage was reported.

In 1903…northwest winds were sustained to 48 mph with gusts to 53 mph.

In 1936…light dust spread over the city from the east on southeast winds gusting to 25 mph. The surface visibility was reduced to about 2 miles at times.

In 1940…this date marked the start of the longest period without snow…200 days…through November 3…1940. A trace of snow fell on both April 17…1940…and November 4…1940.

In 1963…strong winds were prevalent all day across metro Denver. West-northwest winds gusting to 60 mph produced some blowing dust at Stapleton Airport.

In 1971…a microburst wind gust to 59 mph produced some blowing dust at Stapleton International Airport.

In 1978…high winds caused much blowing dust over the plains. Wind gusts from 80 to 96 mph were reported in Boulder with 80 mph measured on Lookout Mountain. Northwest winds gusted to 43 mph at Stapleton International Airport.

In 2000…high winds developed in the foothills of Boulder County. Peak wind gusts included 71 mph at the National Center for Atmospheric Research mesa lab near Boulder. In Aurora…three workers were injured when strong winds caused a home under construction to partially collapse. Two received minor injuries…while the third worker had to be hospitalized with severe back injuries. South winds gusted to 47 mph at Denver International Airport.

In 2002…strong northeast winds behind a cold front gusted to 53 mph at Denver International Airport where some blowing dust briefly reduced the visibility to 3 miles.

Continue reading April 17 to April 23: This week in Denver weather history →

Colorado Weather, Weather Education

Severe Weather 101 – Severe Weather Awareness Week wrap up

April 16, 2022 Thornton Weather Leave a comment

Supercell thunderstorms like this can be beautiful - but they can also be deadly. Do you know what to do when severe weather strikes? (Stormscape Photography / FLICKR) — Supercell thunderstorms like this can be beautiful – but they can also be deadly. Do you know what to do when severe weather strikes? (Stormscape Photography / FLICKR)

Over the past week we have highlighted some of the severe weather hazards that we face in Colorado every spring and summer in our Severe Weather 101 series. The dangers these present are significant and not to be taken lightly.

Tornadoes grab most of the headlines and certainly are a danger however others like lightning and flooding are more common and actually claim more lives. We ask all of our readers to please, take the time to review these important articles – they could save yours and your family’s lives!

The National Weather Service has published a nice wrap up of Severe Weather Awareness Week that covers all the basics – see it below. For more in depth information, please use the links at the bottom to view each article on our Severe Weather 101 series. Be safe and be weatherwise!

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
600 AM MDT SAT APR 16 2022

SEVERE WEATHER AWARENESS WEEK IN REVIEW

Severe Weather Awareness Week in review…

Severe Weather Awareness Week in Colorado concludes today. During the past week we have presented information and safety rules for tornadoes, lightning and wildfires, floods and flash floods, straight-line thunderstorm winds, hail, and our warning programs.

We will now review some of the most important safety rules in our effort to build a Weather-Ready Nation.

Be weather-wise by staying informed on expected weather in your area. The National Weather Service is typically aware of the potential for severe weather many hours or even days before any severe weather watches or warnings are issued, providing forecast products to heighten your awareness. A Weather Story product is posted each day on National Weather Service Internet pages and Facebook pages which includes a map and text on possible hazardous weather expected within the next seven days.

A Hazardous Weather Outlook is also issued daily with information on possible hazardous weather through the next seven days. A watch is issued when conditions for severe weather or flooding become possible. A warning is then issued when life threatening conditions are imminent or occurring.

Tornadoes

The best way to protect yourself from tornadoes is to have a plan of action. The safest place to be if a tornado approaches is in a basement or safe room within a well-built structure, or in an underground storm shelter. If none of these options are available, move to a hallway or a small interior room on the lowest floor, usually this is a closet or bathroom. Get under a heavy piece of furniture or in a bath tub and cover yourself with blankets. Remember, the greatest risk of injury from tornadoes is from flying debris.

Modular homes and mobile homes, even those tied down, offer little protection from tornadoes. If a tornado approaches, leave those locations and seek safety in a nearby sturdy building or storm shelter.

If you are driving in open country and see a tornado, if time permits, the best thing to do is simply drive away from the tornado path. Do not take shelter beneath a highway overpass. Wind speeds may actually be higher in these areas and often become collection points for debris.

If you are caught outside and cannot seek shelter inside a sturdy structure, crawl into a culvert or lie down in a narrow ditch or ravine and cover your head. But remember that the worst place to be when a tornado threatens is outside in the midst of flying debris.

Lightning

Lightning usually kills and injures more people in Colorado than any other thunderstorm hazard. Lightning also causes many wildfires.

The best defense to protect yourself against a lightning strike is to plan ahead and avoid being caught where you might be vulnerable. Check weather forecasts prior to venturing out, especially if you are heading into the mountains. Plan outdoor activities early in the day before storms develop.

If thunderstorms threaten, seek shelter in a building or in an enclosed metal-roof vehicle, making sure all windows and doors are closed. Never seek shelter under an isolated tree. During thunderstorms, stay off corded telephones, away from electrical devices, and away from plumbing. Also get out of shower stalls, bath tubs, swimming pools and lakes when lightning is nearby.

You should wait at least 30 minutes after the last sound of thunder before resuming outdoor activities. When thunder roars…go indoors.

Floods and Flash Floods

The Big Thompson Flood in 1976 claimed the lives of 144 Coloradoans and serves to remind us of the dangers of floods. (USGS)

When flooding or flash flooding is possible, you should remain alert and be ready to quickly evacuate to higher ground or climb to safety. Flash floods often occur suddenly and without warning. You need to follow some basic flood safety rules:

Do not camp or park your vehicle along streams and washes, particularly during threatening conditions.
If you are near a river, be aware of water levels and be prepared to move to higher ground if river levels rise.
Do not enter areas that are already flooded.
If walking or fishing along a river, be aware that erosion from swift running water can cause river banks to collapse.
Never let your children play around high water, storm drains, viaducts or arroyos.

At least half of all flash flood fatalities are vehicle related. While driving your automobile, look out for flooding at highway dips, bridges and low areas. Two feet of moving water will carry away most vehicles. Never attempt to drive across a flooded road. And be especially cautious at night when it is difficult to see flood dangers.

Strong Straight-Line Winds

Straight-line winds from thunderstorms, including microbursts, can become quite strong, even reaching speeds in excess of 100 mph in extreme cases. When thunderstorms approach, high winds can suddenly develop, causing things on the ground to become swift moving airborne missiles with a potential force to injure or kill. As with any thunderstorm, seek shelter before the storm arrives.

Hail

Large hail can pose a danger to animals and people. Hail also produces considerable damage to crops and personal property each year in Colorado. Again, get indoors before thunderstorms arrive. A fall of small hail can suddenly change to a fall of very large ice missiles which can injure or kill. Make efforts to protect personal property before storms threaten.

Warning Notification

When thunderstorms threaten, tune to NOAA All-Hazards Weather Radio, The Weather Channel, or your local radio or television stations. Also check the Internet web site from the National Weather Service office serving your area. And if you have a relatively new cell phone you should receive Tornado and Flash Flood Warnings on your phone if you are in the area of the warning.

During threatening weather days, plan the actions you will need to take so that you will be prepared if dangerous weather conditions actually develop.

NOAA’s National Weather Service wishes you a safe severe weather season.

This is a recap of a five part series on Colorado’s severe weather.

Colorado Weather, Severe Weather, Thornton Weather, Weather Education

Severe Weather 101 – Lightning and lightning safety

April 15, 2022 Thornton Weather Leave a comment

This is NOT the time to be outside. (michaeljames / FLICKR)

Of all the weather types associated with thunderstorms – hail, tornadoes, floods, etc – lightning is usually the most dangerous. In the United States there are an estimated 25 million cloud to ground lightning flashes each year and each one is a potential threat to life and property.

During the past 10 years there has been an annual average of 39 lightning fatalities in the United States. Last year, 23 people lost their lives due to lightning.

Colorado is ranked # 2 in lightning related deaths (2001 – 2010) so the danger this presents to life and property is very significant for us. It is interesting to note though that Colorado ranks only 32nd in the number of cloud to ground strikes over that same period. Which means, in short, we have fewer strikes than many other states and yet more deaths.

This highlights the fact that, quite frankly, folks here in Colorado are not aware of the dangers lightning presents and they do not take proper steps to protect themselves. One of the great things about Colorado are the outdoor activities we all enjoy, but there comes a time when we need to head indoors.

Continue reading Severe Weather 101 – Lightning and lightning safety →

Colorado Weather, Severe Weather, Thornton Weather, Weather Education

Severe Weather 101 – Hail and Wind

April 14, 2022 Thornton Weather Leave a comment

Straight line winds can be as damaging as a tornado. This image is from a park in Tennessee. (NWS)

During the spring and summer months in Colorado, a wide array of severe weather can strike. Tornadoes may grab all the headlines, but straight line winds and hail can do a great amount of damage in their own right – and they are more common.

Straight line winds are winds out of a thunderstorm and are classified as severe when they hit 58 mph. These winds can reach tornado and hurricane force and as a result, cause property damage and can injure and even kill animals and humans.

These winds are usually the result of air cooling rapidly due to precipitation or evaporation. As the cooler air is heavier than the surrounding warmer air, it rushes downward, accelerating toward the ground and spreads out as it hits, much like pancake batter being poured onto a griddle.

Continue reading Severe Weather 101 – Hail and Wind →

Thornton Weather

Denver sets low temperature record for April 13

April 13, 2022 Thornton Weather Leave a comment

There was definitely a chill in the air this morning and the data shows it was record-setting.

As measured at Denver International Airport, the official low for the Mile High City hit 10 degrees this morning. This easily bests the previous record low for the date of 15 degrees set just two years ago in 2020.

Here in Thornton, we weren’t quite as cold with a low of 13 degrees.

We will warm up some today but temperatures will remain well below normal and we will again be dealing with blustery winds.

Colorado Weather, Severe Weather, Weather Education

Severe Weather 101 – Floods and Flash Floods

April 13, 2022 Thornton Weather 1 Comment

The Big Thompson Flood in 1976 claimed the lives of 144 Coloradoans and serves to remind us of the dangers of floods.

For much of Colorado, floods and flash floods present a grave danger to life and property. These usually are the result of one of two things – spring snow melt occurring rapidly or a severe thunderstorm. Colorado is very susceptible to flash flooding and these occur somewhere every year in the state.

The waters from flash floods can move with extraordinary speed and strike with little or not warning. Their force can be extremely destructive and when coupled with trees, dirt, rocks and other debris they carry downstream, they are deadly.

Flooding is the number one weather killer in the United States.

Continue reading Severe Weather 101 – Floods and Flash Floods →

Climatology, Colorado Weather, Severe Weather, Thornton Weather, Weather Education

Severe Weather 101 – Tornadoes and tornado safety

April 12, 2022 Thornton Weather 1 Comment

Last year's Windsor Tornado highlights the very real danger twisters present in Colorado. Do you know when to do when one strikes? — The 2008 Windsor Tornado highlights the very real danger twisters present in Colorado. Do you know when to do when one strikes?

One fact that may surprise those new to Colorado is that we are actually on the western edge of the infamous Tornado Alley. This large swath of land comprises much of the nation’s midsection and is a unique place as the United States sees more tornadoes than any other place on earth. In fact, tornadoes have been recorded in all 50 states including Alaska and Hawaii.

Closer to home, Colorado sees our share of these storms. In fact, one metro area county – Weld County – holds the distinction of being the “tornado capital of the world.” With 252 tornados from 1950-2011, no single county in the nation has had more tornadoes! Adams County is number two in the state and isn’t far behind with 156 over that same period. Granted these numbers are skewed a bit simply due to the sheer size of those counties, but it does serve to highlight the real danger that tornadoes present.

Even here in the metro area tornadoes are a real danger. The Thornton area was struck in 1981, one of the worst tornadoes to strike the Denver area in history. At 2:30 p.m. this tornado touched down and by 2:45 p.m., the tornado had hit Thornton City Hall. The tornado’s destruction sent 53 injured people to hospitals, 25 homes were destroyed and 239 structures were damaged.

One common myth is that tornadoes don't strike metropolitan areas. This has been disproved many times including here in Colorado in 1982 when an F2 tornado struck Thornton. Image courtesy the City of Thornton archives. — One common myth is that tornadoes don’t strike metropolitan areas. This has been disproved many times including here in Colorado in 1981 when an F2 tornado struck Thornton. Image courtesy the City of Thornton archives.

The most well known tornado outbreak in the metro area occurred on June 15, 1988. Five tornadoes resulted in seven injuries and damage in excess of $15 million.

We all of course also remember in 2008 when the town of Windsor, not far from Denver, was struck with an EF-3 tornado that claimed one life and destroyed and damaged hundreds of buildings.

The greatest threat for tornadoes occurs during late spring and early summer when you have a combination of heat and moisture in the lower atmosphere. Here in Colorado, tornadoes are frequent from May through August with June being the most active month.

However, there is no hard and fast rule for when tornadoes strike, as Colorado witnessed on March 29, 2007 when Holly, Colorado was struck by an EF-3 tornado with winds of 165 mph. Two women lost their lives as a result of that event and 160 homes were damaged.

Colorado ranks 10th in terms of the number of tornadoes with 1,911 events from 1950-2011. One good thing is that our high altitude and drier air do make it harder for the monster supercells that spawn the biggest tornadoes to form. Most of our tornadoes are small and short lived. Further, thanks to the wide open spaces of the eastern half of our state, many strike sparsely populated areas. This is reflected in the fact that we rank 38th for tornado related deaths.

Continue reading Severe Weather 101 – Tornadoes and tornado safety →

Colorado Weather, Severe Weather, Thornton Weather, Weather Education

Severe Weather 101 – Watches, Warnings and More

April 11, 2022 Thornton Weather

Last year's Windsor tornado highlighted just how dangerous weather in Colorado can be. Are you and your family prepared? Do you know what the watches and warnings all mean? — The 2008 Windsor tornado highlighted just how dangerous weather in Colorado can be. Are you and your family prepared? Do you know what the watches and warnings all mean?

We’ve all seen TV or Internet news of a weather related watch or warning being issued. But, how many really know what they mean? There is a pretty big difference between the two and it is important to be aware just what it means to you so you can take the appropriate precautions.

Dozens of weather related fatalities occur every year in Colorado, many simply out of ignorance. Taking the time to be aware of the conditions around you and taking appropriate action will keep you from becoming a statistic.

Naturally you can get information on current advisories from television as local stations usually do a good job of “crawling” them on the screen when they are issued. This works well if you have a TV available but if not, the radio would be a secondary source. The Internet and the National Weather Service’s website are a great one when at a computer.

The problem with relying on news media or the Internet is that their ability to warn you of a developing weather situation is dependent on your monitoring them. Severe weather can strike without little warning. How will you know if severe weather is about to strike if you don’t have the TV or radio on?

Your first line of defense – NOAA All Hazards Radio

NOAA Weather Radio For just about anywhere, a special radio that picks up the NOAA’s All Hazard Radio broadcasts is the way to go and provides information from the source. Oftentimes simply called a weather radio, we highly recommend every household have one of these.

What does a weather radio sound like? Click here to listen in live.

These radios are relatively inexpensive and allow you to be immediately notified of official National Weather Service warnings, watches, and forecasts as well as other hazard information like earthquakes, avalanches, chemical spills, and even AMBER alerts. In fact, with these radios, you will be notified at the exact same time the news media is made aware giving you a head start on preparing for a developing situation.

To learn more about these devices and what you should look for when buying one, click here.

A high-tech alternative – Cell phone weather apps

Many people now have smartphones that allow for downloadable apps and weather-related ones are among the most popular.

All of these applications have a number of weather related features in common. All provide current conditions for either the location the user is in now or for saved locations and all provide some sort of radar.

Most can be configured to sound an alert when the National Weather Service issues a watch or warning. While they are no substitue for a weather radio, these apps provide you with immediate notification no matter where you are at.

For a look at some of these weather apps and their features, click here.

Continue reading Severe Weather 101 – Watches, Warnings and More →

Weather History

April 10 to April 16: This Week in Denver Weather History

April 10, 2022 Thornton Weather Leave a comment

April can be a very eventful weather month and we see that in our look back at this week in Denver weather history. Particularly notable are many major snow events including two in recent history – one in 2001 and another in 2005.

From the National Weather Service:

7-12

In 1959…snow falling over a 5-day period totaled 20 to 30 inches just east of the mountains…while over the plains blizzard conditions closed schools and blocked highways. The second big storm in two weeks dumped 16.4 inches of snowfall on Stapleton Airport with the most…11.6 inches… Occurring on the 8th. East winds gusted to 37 mph on the 9th. Temperatures dipped into the single digits on the mornings of the 7th and 12th when 7 degrees were registered. Low temperature records for the dates were set on the 9th…10th…and 12th. The cold temperatures caused streets to glaze with ice…resulting in the death of a pedestrian who was struck by a car in Denver. Three people died from heart attacks while shoveling the heavy… Wet snow.

8-10

In 1999…a windstorm caused 20 million dollars in damage along the Front Range urban corridor from Fort Collins south to pueblo and to the east over the plains…making the storm equal to the costliest windstorm ever…which occurred in Boulder on January 17…1982. In metro Denver… Several homes were damaged as shingles were blown off roofs. Large pieces of a roof torn off a strip mall in Lakewood damaged several cars in a parking lot. Most of the damage to homes consisted of broken fences…awnings…doors…and windows. Scores of automobiles suffered broken or cracked windshields and paint damage from flying debris. Multiple accidents were triggered as several tractor-trailer rigs were blown on their sides by the strong cross-winds. Blowing dust and dirt caused near zero visibilities at times. Both I-25 and I-76 were closed north and northeast of Denver. State Highway 93 was closed between Golden and Boulder. Several trees…power poles…and power lines were downed…causing a number of outages as well as sparking a few small grass fires. Highest wind gusts reached 112 mph atop Niwot Ridge near the continental divide west of Boulder…102 mph at Wondervu…100 mph at the National Center for Atmospheric Research mesa lab in Boulder…98 mph at the national wind technology center near Broomfield…96 mph on Rocky Flats…92 mph at Jefferson County Airport near Broomfield and on the University of Colorado campus in Boulder…and 90 mph at Highlands Ranch in southwest metro Denver. Winds gusted to 48 mph at Denver International Airport.

9-10

In 1900…rain changed to heavy snow and totaled 6.8 inches in downtown Denver overnight. A thunderstorm occurred on the 9th. North winds were sustained to 32 mph with gusts to 38 mph on the 10th. Precipitation totaled 1.39 inches.

In 1933…post-frontal heavy snowfall totaled 9.4 inches in downtown Denver. East winds were sustained to 21 mph with gusts to 22 mph on the 9th.

In 1944…7.0 inches of snow fell on downtown Denver. Northeast winds were sustained to 24 mph on the 9th.

In 1977…the two warmest days of the month resulted in two temperature records being set. High temperature of 81 degrees on the 9th set a new record maximum for the date. High temperature of 80 degrees on the 10th equaled the record maximum for the date. The unusually warm weather for so early in April produced a late afternoon thunderstorm on the 10th.

In 1993…strong downslope winds occurred along the Front Range. While the strongest winds were in the foothills north of Denver…wind gusts to 69 mph were recorded at Jefferson County Airport in Broomfield. Northwest winds gusted to 39 mph at Stapleton International Airport.

In 2004…a spring storm brought heavy snow to metro Denver. The heaviest snow fell in the foothills and over and near higher terrain. Snowfall totals included: 20 inches near Jamestown; 18 inches atop gold hill; 17 inches near Evergreen; 15 inches at Nederland and Eldora; 13 inches at Blackhawk; 11 inches at Aspen Springs; 9 inches in Louisville; 8 inches at Ken Caryl; 6 inches at Niwot… Near Sedalia…and in Thornton; 5 inches in Lakewood… Lyons…and Westminster. Snowfall was 4.4 inches at Denver Stapleton. Northwest winds gusted to 21 mph at Denver International Airport.

In 2008…a very moist storm brought heavy snow to parts of the Front Range foothills. Storm totals included: 12.5 inches at Aspen Springs…11 inches…4 miles west- southwest of conifer; with 10.5 inches…3 miles north of central city and 6 miles southwest of Evergreen. Lesser amounts of 5 to 9 inches were observed elsewhere. North winds gusted to 43 mph at Denver International Airport on the 10th…and 1.8 inches of snow fell at the former Stapleton International Airport.

9-11

In 1951…heavy snowfall totaled 9.4 inches at Stapleton Airport. The storm was accompanied by strong northeast winds gusting to 43 mph.

In 1953…heavy snowfall occurred at Stapleton Airport where 7.9 inches of snow were measured. North winds gusted to 29 mph.

In 1994…6 to 14 inches of heavy snow buried much of eastern Colorado…closing many schools and I-70 from east of Denver to the Kansas border. Rain changed to snow on the 9th…and snow continued through the 11th. Snowfall totaled 5.7 inches at Stapleton International Airport…but maximum snow depth on the ground was only 3 inches on the 10th due to melting. East winds gusted to 26 mph on the 9th.

In 1995…a major spring storm dumped 8 to 16 inches of snow in the foothills west of Denver. Snowfall totaled 8.3 inches at the site of the former Stapleton International Airport…but most of the snow melted as it fell with the maximum snow depth on the ground of only 2 inches. Five-to 6-inch snow accumulations occurred over southern portions of metro Denver and eastward onto the plains. Northeast winds gusted to 36 mph at Denver International Airport on the 10th. I-70 was closed for several hours east of Watkins to the Kansas border due to drifting snow and near whiteout conditions. High temperature of only 29 degrees on the 10th was a record low maximum for the date.

9-12

In 1901…rain changed to snow and totaled 10.8 inches in downtown Denver over the 4 days. Northeast winds were sustained to 28 mph with gusts to 31 mph on the 11th. Temperatures hovered in the 30’s.
10

In 1896…southwest winds were sustained to 40 mph with gusts to 60 mph. The apparent Chinook winds warmed the temperature to a high of 76 degrees.

In 1899…northwest Chinook winds were sustained to 45 mph with gusts as high as 60 mph. The downslope winds warmed the temperature to a high of 73 degrees in the city.

10-11

In 1979…a heavy snow storm produced near-blizzard conditions across eastern Colorado with 10 to 20 inches in the foothills and 4 to 8 inches over the plains. Winds to 35 mph combined with the snow to produce drifts at least 3 feet deep…closing many roads and causing power outages. Travel was interrupted south of Denver when the storm closed both I-25 and State Highway 83. Snowfall totaled only 3.8 inches at Stapleton International Airport where northeast winds gusted 37 mph…causing some blowing snow on the 11th.

In 2001…a potent spring storm dumped heavy snow over metro Denver and the adjacent foothills…while a blizzard roared across the plains to the east of Denver. Snowfall amounts ranged up to a foot and a half across metro Denver and in the foothills. North to northwest winds at sustained speeds of 40 to 50 mph with gusts as high as 60 mph piled the snow into drifts of 3 to 6 feet deep. I-25 southbound was closed at Lincoln Avenue. I-70 to the east was closed at gun club road. The combination of heavy wet snow and damaging winds resulted in widespread electrical outages. Denver International Airport was completely shut down for the first time in its brief 6-year history. Power surges and outages crippled the airport’s massive computer systems. The airport was closed at 5:00 am and did not re-open until mid-afternoon on the 11th. The power outages resulted in businesses and schools closing. Over all of northeastern Colorado…there were 220 thousand customers without power… The worst outage in Xcel Energy’s history. Repairs totaled 1.6 million dollars. Across metro Denver…snow totals included: 18 inches in southeast Aurora…16 inches at centennial airport and Parker…14 inches at Broomfield… 13 inches in Louisville…12 inches at Lakewood and Morrison… 11 inches at Ken Caryl and Thornton…10 inches at the site of the former Stapleton International Airport and in Wheat Ridge…9 inches in Westminster…and 8 inches in Littleton. Thunderstorms preceded the start of the snow on the afternoon of the 10th and were embedded in the snow storm during the early morning hours of the 11th at Denver International Airport where northwest winds gusted to 60 mph on the 11th. Snow storm totals in the foothills included: 17 inches at Genesee…16 inches at Rollinsville… 14 inches at Intercanyon…13 inches in Coal Creek Canyon and near Evergreen…11 inches at Aspen Springs and Chief Hosa…10 inches at Blackhawk…and 9 inches atop Crow Hill.

In 2005…a strong spring storm produced blizzard conditions in areas to the east of Denver and south of I-76 and near- blizzard conditions across metro Denver. The combination of heavy snow and strong winds forced the closure of Denver International Airport…stranding thousands of travelers. Long stretches of I-25…I-70…and I-76 were also closed due to extensive blowing and drifting snow. Snow amounts ranged from 1 to 2.5 feet in and near the eastern foothills and over the Palmer Divide. Drifts were 2 to 5 feet in depth. Downed power lines caused scattered electrical outages. Storm total snowfall amounts in and near the foothills included: 31 inches near conifer; 27.5 inches in Aspen Springs; 25.5 inches near Sedalia and Blackhawk; 25 inches near Bergen Park and around Genesee; 24.5 inches at pine junction and Roxborough Park; 24 inches southwest of Boulder; 23.5 inches at Ken Caryl; 23 inches atop Crow Hill and near Larkspur…Evergreen…and Nederland; 21 inches at Eldora Ski Area; 18 inches at Eldorado Springs and near Castle Rock; 17 inches near Chatfield Reservoir and Perry Park; and 16 inches near Jamestown. Across the city storm total snow amounts were: 22.5 inches in Aurora; 22 inches at Bennett; 20 inches near Arapahoe park and in centennial… Littleton…and south Denver; 17.5 inches near Bennett; 16 inches in Thornton; 15 inches in Lakewood; 14.5 inches in wheat ridge and near Englewood; 14 inches at lone tree and in Arvada; and 9.9 inches at Denver Stapleton. North winds were sustained from 25 to 35 mph with gusts to 46 mph at Denver International Airport on the 10th.

10-12

In 1997…a pacific storm produced heavy snow on the 10th and the 11th in and near the foothills with 6 to 8 inches at Louisville and turkey creek canyon…5 inches at Morrison… And only 3.5 inches at the site of the former Stapleton International Airport. Northeast winds gusted to 24 mph at Denver International Airport. The storm also brought unseasonably cold weather with 5 new temperature records equaled or broken. Record low temperatures of 8 and 6 occurred on the 11th and 12th. Record low maximum temperatures of 20…19…and 30 occurred on the 10th…11th… And 12th respectively. This was also only the second time on record that the temperature had failed to reach the freezing mark for 3 consecutive days in April.

10-14

In 1927…post-frontal rain on the 10th changed to snow on the 11th and continued through the 14th. Snowfall totaled 8.5 inches from precipitation of 1.28 inches. North winds were sustained to 26 mph with gusts to 29 mph on the 13th.

In 1954…strong and gusty southeast winds blew all day. Winds as high as 30 mph with gusts to 50 mph produced some blowing dust at Stapleton Airport.

In 1966…a tornado was sighted in an open area of southeast Denver. Slight wind damage in the area was not directly attributable to the tornado. Later in the day…a pilot reported a funnel cloud 10 miles southwest of Denver. Hail to 1/2 inch in diameter fell at Stapleton International Airport.

In 1984…strong Chinook winds gusted to 72 mph at Rocky Flats south of Boulder; speeds reached 70 mph in both Lakewood and Boulder. At Stapleton International Airport… Northwest wind gusts to 52 mph were recorded.

In 2004…an afternoon cold front produced north winds sustained to 36 mph with gusts to 53 mph at Denver International Airport. Light snowfall was 1.1 inches at Denver Stapleton through the evening.

Continue reading April 10 to April 16: This Week in Denver Weather History →

Severe Weather, Weather Education

Severe Weather Awareness Week in Colorado gets started

April 10, 2022 Thornton Weather Leave a comment

Thornton, Colorado tornado damage, 1981 — In 1981 a tornado ripped through Thornton and caused major damage. Last year, funnel clouds were spotted across much of the area. Image courtesy City of Thornton archives.

As is customary as we get further into spring, this coming week has been proclaimed Severe Weather Awareness Week. This is an opportunity for the public to get reacquainted with the dangers severe weather presents in Colorado.

Tornadoes, lightning, hail, severe wind and flooding are very real hazards that Coloradans face every year during severe weather season. It is important that you know what to do to protect you and your family.

Just 12 years ago in what was Denver’s weather story of the year, we suffered through a period of unusually severe weather including a tornado that ripped through the Southlands Mall.

Thirteen years ago on May 22nd an EF3 tornado raced north through Weld and Larimer counties resulting in one fatality near Windsor and causing several injuries and destroyed or heavily damaged hundreds of homes.

And of course in 1981 Thornton was the site of the worst tornado to ever strike the Denver metro area.

Tornadoes may get all the press but other severe weather can be damaging and deadly.

Just eight years ago, late summer flooding caused millions of dollars of damage across northeastern Colorado. It was 45 years ago that thunderstorms brought a raging torrent of water down the Big Thompson and caused one of Colorado’s worst natural disasters. Eleven years ago hail struck the Thornton area causing damage to homes and vehicles.

Do you need to jog your memory about the Windsor tornado? Watch the amazing video below.

In conjunction with the National Weather Service’s statements on Severe Weather Awareness Week, ThorntonWeather.com will be publishing our Severe Weather 101 series. Each day this week a weather hazard will be discussed in depth and we will outline protective measures you can take to keep yourself and your family safe. Please be sure to check back every day to read these important message.

Continue reading Severe Weather Awareness Week in Colorado gets started →

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