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.

» Click here to read the rest of Severe Weather 101 – Floods and Flash Floods

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.

• Think Denver can’t get hit with a tornado?  Think again! Check out the Colorado tornado history map

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 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.

» Click here to read the rest of Severe Weather 101 – Tornadoes and tornado safety

A weak cold front that moved in last night coupled with a disturbance coming through today will mix up our weather a bit. Temperatures will cool down but remain above normal and we see just a chance for a PM shower or thunderstorm.

The day starts with partly clear skies and similar conditions will be with us into the afternoon after which coverage will increase. Temperatures today will top out in the upper 60s, cooler than yesterday but still a good bit above normal.

The afternoon brings a chance for a shower or thunderstorm with the best opportunity coming between about 3:00pm and 6:00pm. Only scattered activity is expected with most action being to our south.

Tonight, a light rain shower may be seen before midnight with lows in the low 40s.

A very nice looking spring day gets things started for the workweek. We will enjoy a good dose of sun and temperatures well above normal.

Mostly sunny skies will above for much of the day with a few mid-level clouds popping up. Temperatures start out cool then will warm to a high in the low 70s, well above the average high for the date of 61 degrees.

Tonight, we will have partly cloudy skies with lows in the low 40s.

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

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.

» Click here to read the rest of Severe Weather 101 – Watches, Warnings and More

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, Colorado Governor John Hickenlooper has declared this coming week 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 nine 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.

Ten 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 four years ago, late summer flooding caused millions of dollars of damage across northeastern Colorado.  It was 40 years ago that thunderstorms brought a raging torrent of water down the Big Thompson and caused one of Colorado’s worst natural disasters.  Six 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.

» Click here to read the rest of Severe Weather Awareness Week in Colorado gets started

April 14 to April 20: This Week in Denver Weather History

Springtime in Colorado can certainly be pleasant but it can also bring an amazing array of interesting weather. Our look back at this week contains everything from snowstorms and damaging wind to severe thunderstorms with hail and tornadoes.

From the National Weather Service:

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.

12-14

In 1933…heavy snowfall of 5.6 inches occurred in downtown Denver on the 12th and 13th behind a vigorous cold front… Which presented an awe-inspiring spectacle as it approached the station during the late afternoon of the 12th. Brilliant white wind-torn cumulus clouds were sandwiched by a brownish- tan dust cloud at the surface and dark blue cumulus clouds above. The dust cloud storm rapidly enveloped the station with northeast winds sustained to 38 mph and gusts to 44 mph producing much blowing dust…which was accompanied by rapidly falling temperatures and rising pressure. Moist snowfall started in about an hour and continued to midday on the 13th. Record low temperatures of 17 and 15 degrees occurred on the 13th and 14th respectively. The high temperature of only 27 degrees on the 13th was a record low maximum for the date.

12-15

In 1927…snowfall totaled 8.5 inches in downtown Denver. Most of the snow fell on the 14th. Northwest winds were sustained to 27 mph during the storm.

13-14

In 1968…high winds struck Boulder. Sustained winds of 50 mph with gusts as high as 102 mph were recorded at the National Center for Atmospheric Research…while in downtown Boulder winds peaked to 73 mph. The winds damaged a building under construction and some homes in south Boulder. Northwest winds gusted to 35 mph at Stapleton International Airport on the 13th.

In 1996…a potent spring storm strengthened just east of Denver. Blizzard conditions developed over eastern Adams and eastern Arapahoe counties. Strong northerly winds ranging from 25 to 50 mph…cold temperatures…and heavy snowfall combined to create very hazardous conditions. The strong winds whipped snow in drifts 3 to 4 feet high. High winds and heavy wet snow downed power lines and caused traffic accidents. Some roads were closed. Snowfall totaled 15 inches at Strasburg…while only 2.1 inches of snow fell at the site of the former Stapleton International Airport. North winds gusted to 40 mph at Denver International Airport on the 13th.

In 2011…a potent spring snowstorm brought heavy snow to Front Range mountains and foothills. Storm totals included: 16.5 inches near Blackhawk; 16 inches at Nederland; 15.5 inches at Coal Creek Canyon and 5 miles northeast of Ward; 15 inches at Allenspark; 12.5 inches… 5 miles northwest of Idaho Springs; 12 inches at Echo Mountain ski area; and 10.5 inches near Georgetown.

13-15

In 1945…heavy snowfall totaled 9.8 inches in downtown Denver. Most of the snow…4.8 inches…fell on the 14th. Snow fell for a total of 53 consecutive hours. This was the second big snow in less than 2 weeks. The air mass was very cold for April. High temperatures of 21 degrees on the 14th and 32 degrees on the 15th were record low maximums for those dates.

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.

14

In 1872…high winds damaged buildings in the city. At 9:00 am west winds commenced to blow a perfect gale… Averaging 40 mph sustained until 9:00 pm.

In 1904…west winds sustained to 40 mph with gusts to 48 mph warmed the temperature to a high of 74 degrees.

In 1918…a thunderstorm produced hail that covered the ground to a depth of 1/2 inch. The stones varied in size from small shot to a cherry stone. Rain and melted hail totaled 0.70 inch. There was no reported damage.

In 1935…northeast winds sustained to 30 mph caused a dust storm across the city. The visibility was greatly reduced by blowing dense dust.

In 1970…strong winds caused mostly light but widespread damage to trees…roofs…power lines…and other property across the northeastern Colorado plains. Wind gusts of 45 to 60 mph were common. Southwest wind gusts to 44 mph occurred at Stapleton International Airport.

In 1995…high winds spread from the foothills onto the plains. West winds gusted between 70 and 90 mph in the foothills and 50 to 70 mph on the plains. West winds were clocked to 51 mph at Denver International Airport. Most of the significant wind damage occurred north and east of metro Denver.

14-15

In 1873…north winds blew a gale during the afternoon on both days. Winds were brisk throughout each day.

In 1902…snowfall totaled 6.0 inches in downtown Denver. Most of the snow melted as it fell. Northeast winds were sustained to 20 mph.

In 1910…strong winds occurred on both days. Northeast winds were sustained to 52 mph on the 14th. North winds were sustained to 44 mph on the 15th.

In 1921…heavy snowfall and strong winds produced near- blizzard conditions in the city. Snowfall totaled 10.0 inches. Strong north winds sustained to 48 mph with gusts to 54 mph on the 15th produced drifts to several feet in depth. The heavy wet snow caused extensive damage to trees…utility poles…and buildings. Precipitation from the storm was 1.73 inches. Very heavy snow also fell in the foothills. At silver lake…in the mountains west of Boulder…95 inches of snow fell in 32.5 hours on the 14th and 15th.

In 1935…dense dust…apparently behind a dry cold front… Enveloped the city at 1:00 pm on the 14th and persisted through the night. The dust blew into the city on northeast winds sustained to 30 mph with gusts to 32 mph. By mid-morning on the 15th…the dust had become light and continued as such into the evening. North winds were sustained to only 13 mph on the 15th.

In 1999…a spring storm dumped heavy snow over portions of metro Denver. Nearly 2 feet of snow fell in the foothills with half a foot to a foot over western and southern suburbs. The heavy snow alleviated drought conditions and associated high fire danger that prevailed during much of the winter season. Snowfall totals included: 22 inches in Coal Creek Canyon…20 inches at Wondervu…19 inches at Genesee…17 inches near Evergreen and Nederland and at Idaho Springs and tiny town…14 inches at Georgetown…13 inches at Morrison…10 inches near Sedalia…9 inches in south Boulder… 8 inches at Highlands Ranch and Wheat Ridge…and 7 inches at Littleton and Parker. Only 3.4 inches of snow fell at the site of the former Stapleton International Airport. North- northwest winds gusted to 41 mph on the 15th at Denver International Airport.

15

In 1874…light snow developed around daybreak and became moderate to heavy by mid-morning and continued into the early evening. While most of the snow melted as it fell… Total precipitation from the melted snow was 0.95 inch. This would make the estimated snowfall nearly 10 inches.

In 1963…high winds were widespread across metro Denver. West winds gusted to 63 mph in Denver at Stapleton Airport with sustained winds of 35 mph and gusts to 70 mph in downtown Boulder. The winds caused extensive damage to buildings and other property. Visibility was briefly reduced to 1/2 mile in blowing dust at Stapleton Airport.

In 1998…another spring storm brought heavy snow to the foothills. Thirty to 40 vehicles were involved in accidents along I-70 near Georgetown. The combination of poor visibilities…slick roads…and careless drivers led to the multi-car pileups. Only minor injuries were reported. The accidents forced the closure of all of I-70’s eastbound lanes. Snowfall totals included 12 inches at Genesee and 10 inches at Aspen Springs…Chief Hosa…Georgetown…near Morrison…and on North Turkey Creek. Only 0.1 inch of snow fell at the site of the former Stapleton International Airport. East winds gusted to 30 mph at Denver International Airport.

In 2002…unseasonable warm weather resulted in two records being broken. The high temperature of 84 degrees was a record maximum for the date. The low temperature of 57 degrees was a record high minimum for the date.

15-16

In 1900…heavy rainfall totaled 2.33 inches. A trace of snow was mixed with the rain at times.

In 1950…thunderstorms and heavy rain behind a cold front produced 2.13 inches of rain in 24 hours at Stapleton Airport.

In 2003…a fast moving pacific storm system moved across Colorado allowing strong winds to develop over the eastern foothills and metro Denver. Northwest winds gusted to 59 mph at Denver International Airport late in the evening of the 15th.

In 2016…1.22 inches of precipitation was measured at Denver International Airport which was the greatest daily amount for the month.

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

In 1960…a wind storm struck all of metro Denver. Estimated wind gusts up to 80 mph were registered in Boulder. At Stapleton Airport sustained west-northwest winds over 50 mph with gusts as high as 70 mph produced some blowing dust. The high winds damaged buildings…power and telephone lines…and signs. Five people were injured in metro Denver as a result of the wind storm. Blowing dust reduced visibility at times. The winds were strong and gusty for most of the day.

» Click here to read the rest of April 14 to April 20: This Week in Denver Weather History

A bit of a mixed bag of weather for the three day period. Unsettled, cool conditions will be with us Friday and Saturday then Sunday rebounds and will offer the nicest day of the period.

For today, mostly cloudy skies will be above throughout the day. Highs will only be around 40 degrees. By mid to late afternoon, scattered, light showers will develop, initially as rain then changing to snow. Light accumulations may be seen overnight.

Cloudy skies will be above tonight with lows in the mid-20s.

Saturday morning may continue to see some light precipitation in the form of a wintry mix of drizzle and snow. That should end by about noon then we will dry out. Mostly cloudy skies will be above with highs in the mid-40s.

Overnight Saturday into Sunday morning, mostly cloudy skies will be above initially then will begin to clear after midnight. Lows will be around 30 degrees.

Sunday finally sees the weather straighten out. Mostly sunny skies will be above with highs in the low to mid-60s.

Thornton, Colorado seasonal snowfall totals as of April 11, 2019. Click for larger image. (ThorntonWeather.com)

Thornton hasn’t had any truly big time snows this year but we have managed a number of respectable ones and that shows in our seasonal snow totals.

As of today, Thornton has received 49.1 inches of snow for the season. That is just slightly below our running 13 year seasonal average of 53.1 inches.

As for Denver, officially, the Mile High City has recorded 43.2 inches thus far this season as measured at DIA. The all-time seasonal average snowfall for Denver is 57.1 inches (55.3 inches 30 year average) so there is still ground to make up there to get near average.

With half of April and all of May to go, there’s still plenty of time to add to those numbers.

In case you were wondering… The average date of Denver’s last snowfall is April 27th. The latest? June 12, 1947 when a trace was recorded. The latest measurable snowfall was 0.4 inches on June 1, 2919.

A nice snowstorm yesterday but certainly not on par with the previous one. We did receive 4.8 inches of snow on the grass while much of what hit the streets melted. Today, we dry out but temps remain cold and we will see some breezy winds.

Cloudy skies start us off and the balance of the day will be mostly cloudy to cloudy. Snow should be done by about 7:00am or soon after.

Temperatures will top out around the 40 degree mark. Winds will be a bit breezy from late morning into the late afternoon so it will feel colder than that.

We may see a few flakes of snow in the late afternoon and early evening but no accumulation is expected.

Tonight, mostly cloudy skies will be above with lows in the low 20s