Thornton, Colorado, USA
UpdatedThu, 16-Aug-2018 9:05pm MDT 


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Severe Weather 101 – Watches, Warnings and More

Monday, April 16th, 2018 6:15am MDT
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 RadioFor 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.

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

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Thornton’s workweek starts out with unseasonably warm temps, calm conditions

Monday, April 16th, 2018 5:00am MDT

A pretty good way to start things off. High pressure will dominate today leading to one of the warmest days of the year so far.

The day starts with mostly sunny skies and similar conditions will be above for most of the day. The evening will bring a brief increase in cloud cover. Temperatures start out on the chilly side but will warm up nicely with a high today around 77 degrees. The average high for today’s date is 61 degrees.

Tonight, cloud cover decreases and lows will dip to the mid-40s.

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April 15 to April 21: This week in Denver weather history

Sunday, April 15th, 2018 4:13pm MDT
This week in Denver weather history

April 15 to April 21: This week in Denver weather history

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:


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.


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 the those dates.


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.


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.


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.


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 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 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.


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


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.

» Click here to read the rest of April 15 to April 21: This week in Denver weather history

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Severe Weather Awareness Week in Colorado gets started

Sunday, April 15th, 2018 6:00am MDT

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.

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

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Cold and blustery conditions start Thornton’s weekend to be followed by warmer, drier conditions

Friday, April 13th, 2018 5:31am MDT

We have a little bit of everything Colorado spring offers in our three-day period. We start out with cold conditions, a bit of snow and a good dose of wind. By the end, we will be clear, calm and mild.

Friday will be the most notable weather day as we a strong low pressure system works its way through. We’ll see cloudy skies throughout the day with a few flakes of snow here and there. Little, if any, accumulation is expected. Most notable will be the wind which is going to increase in speeds this morning and then be quite strong in the afternoon and evening.

Tonight, some snow will be seen with maybe just a touch of accumulation. Winds will continue to be strong with low temperatures dipping to the upper 20s.

Saturday offers some improvement with clearing skies and temperatures rebounding to the mid-50s. However, winds are going to continue to be quite breezy throughout the day, settling down in the evening finally.

Saturday night into Sunday morning, partly cloudy skies will be above with lows near freezing.

Sunday is going to be the nicest day of the period, closing out the weekend in fine fashion. Mostly sunny skies will be above, those winds will be gone, and high temperatures will be in the mid-60s.

Have a great weekend!

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Another warm and windy day for Thornton’s Thursday, snow possible tonight and tomorrow

Thursday, April 12th, 2018 5:15am MDT

A little bit of ‘fire and ice’ in the weather forecast over the next 48 hours or so. We start out with unseasonably warm temperatures and high fire danger today but then will see much colder temperatures and a chance for snow tomorrow.

For today, we start out with partly sunny skies then will see some clearing in the afternoon leading to mostly sunny skies. Winds today will be similar to yesterday with speeds increasing by mid to late morning. They will continue to be quite breezy through tonight. Temperatures today will top out in the upper 70s, coming close to Denver’s record high for the date of 79 degrees.

The wind coupled with low humidity and dry fuels means another Red Flag Warning will be in effect until 9:00pm so please be careful.

Tonight, we may see a sprinkle of rain, perhaps some snow after midnight but little or no accumulation is expected. Lows will dip to the mid-30s.

Friday is going to see a return of blustery, wintry conditions with highs only around 40 degrees, chilly winds and some light snow.

What lies ahead for the weekend? Check out the extended forecast here.

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High fire danger, potentially record-setting temps for Thornton’s Wednesday

Wednesday, April 11th, 2018 5:06am MDT

An unseasonably warm day on tap for us today with mercury readings that will push toward the record high for the date. However, those temperatures will be coupled with critical fire danger that has prompted a Red Flag Warning.

The day starts off with a good bit of cloud cover but skies will be clearing by mid-morning leading to mostly sunny skies for much of the day.

Temperatures start out warm, aided by downslope flow, and will head toward a high temperature near the 80 degree mark. Denver’s record high temperature for today’s date is 80 degrees, set in 1982, so it is in jeopardy.

The main story will be winds out of the west that will be increasing in speed this morning and continuing into the early evening. Those winds coupled with dry fuels and low humidity will lead to increased fire danger. A Red Flag Warning has been issued and will be in effect from 11:00am to 7:00pm. Please be careful out there!

Tonight, winds will be calm and skies partly clear as we head for a low in the mid-40s.

Tomorrow, we do this all over again but with even stronger winds and even higher fire danger. Keep an eye on current weather conditions here.

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Thornton to enjoy a very pleasant Tuesday with mild temps, lots of sun

Tuesday, April 10th, 2018 4:53am MDT

Aw, yes, today will be one of those days that you just have to love living in Colorado. It will be, overall, the most pleasant day of the week as we enjoy unseasonably warm temps and lots of sun.

The day starts with sunny skies which will continue through the morning. This afternoon will see clouds increasing but nothing too intrusive. Winds will be relatively light and out of the southwest initially then shifting to the west. As for temperatures, it starts out chilly but then the mercury will begin a steady climb toward an afternoon high in the low 70s.

Tonight, look for mostly cloudy skies with lows dipping to the mid-40s.

Looking ahead, Wednesday and Thursday are going to actually be warmer than today and in fact will probably bring our warmest temperatures of the year thus far. However, we also are going to have a good deal of wind. That wind, the low humidity and dry fuels have already prompted a Red Flag Warning to be issued for Wednesday and Thursday as fire danger increases.

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Some snow and rain possible early Monday, then clearing skies

Monday, April 9th, 2018 5:05am MDT

A disturbance is moving through this morning that has brought us a few sprinkles of rain and may yet deliver some flakes of snow. Any precipitation won’t amount to much though and the latter half of the day will be calm and dry.

Mostly cloudy skies start things off and will continue through the first part of the morning. Then, skies will begin to clear with mostly sunny skies above for the afternoon and evening.

Some snow may be seen in the pre-dawn hours then perhaps mixed with some rain after sunrise. Little to no accumulation is expected. Precipitation should end by noon.

Temperatures start out chilly then will be slow to climb with today’s high in the mid-50s.

Tonight, skies will be mostly clear with lows dipping to near freezing.

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April 8 to April 14: This week in Denver weather history

Sunday, April 8th, 2018 5:33am MDT
This week in Denver weather history

April 8 to April 14: This week in Denver weather history

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:


In 1973…a major spring snow storm dumped 11.6 inches of snowfall over metro Denver. North wind gusts of 30 to 35 mph produced some blowing snow. Most of the heavy wet snow… 10.1 inches…fell on the 7th when temperatures remained in the 20’s. Snow accumulated on the ground to a maximum depth of 9 inches. Low temperature of 5 degrees on the 8th was a new record minimum for the date and the lowest for so late in the season.


In 1913…heavy snowfall totaled 10.9 inches in downtown Denver behind a cold front. Most of the snow fell on the 8th. Northeast winds were sustained to 35 mph with gusts to 38 mph on the 9th.

In 1935…moderate dust blew into the city around 9:00 pm on the 7th and persisted until early afternoon on the 9th. Southeast winds were sustained to around 20 mph on the 7th and 8th. Winds shifting to the west at sustained speeds to 20 mph cleared the dust from the air on the 9th.


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.


In 1885…dense smoke polluted the air until noon.

In 1887…south winds were sustained to 42 mph.

In 1890…northwest winds were sustained to 48 mph with gusts as high as 60 mph.

In 2005…a mixture of strong pressure gradient winds coupled with thunderstorm outflow winds produced high winds across metro Denver. The high winds downed power lines and knocked out electricity to about 19 thousand customers on the east side of metro Denver. High wind reports included gusts to 68 mph in Longmont…61 mph near Castle Rock…59 mph at Centennial Airport…and 54 mph at Denver International Airport.


In 2013…heavy snow developed in and near the Front Range Foothills and Palmer Divide as an upper level trough made its way across southern Colorado. Snowfall was enhanced locally with the presence of an upper level jet. Storm totals included: 23 inches near Eldorado Springs…18 inches just west of Boulder…16.5 inches near Orodell…15 inches…4 miles west-northwest of Boulder; 13 inches at Gold Hill; 12 inches at the National Weather Service Office in Boulder…11 inches in Ken Caryl; 8.5 inches near Morrison; 8 inches at Genesee and Roxborough Park; 7.5 inches near Arapahoe Park; with 6.5 inches at Denver International Airport.


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.


In 1950…strong southwest winds gusting to 58 mph reduced the visibility to 1 mile in blowing dust at Stapleton Airport. Scattered minor wind damage…consisting of falling tree branches and damage to signs…occurred across metro Denver.

In 1989…6 to 12 inches of snow fell at many locations in the Front Range foothills. Boulder received 6 to 8 inches. Five inches (5.0 inches) of snow fell at Stapleton International Airport…causing 2 hour flight delays. I-25 south of Denver was closed for 4 hours due to a 100- car traffic pileup. North winds gusted to 33 mph at Stapleton International Airport where the maximum snow depth on the ground was only 3 inches due to melting.


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 » Click here to read the rest of April 8 to April 14: This week in Denver weather history

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