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Thornton, Colorado, USA
UpdatedTue, 22-Sep-2020 3:15pm MDT 
 

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Tuesday brings cooler temps, gusty winds and elevated fire danger

Tuesday, April 28th, 2020 4:59am MDT

A cold front arrived last night and will help to cool us down some today. Temperatures will still be above normal though and gusty winds are going to drive up the fire danger.

Sunny to mostly skies will be above throughout the day today. Highs will top out right near the 70 degree mark, about 10 degrees cooler than yesterday but still well above average for the date.

Winds will be increasing this morning becoming with gusts to 35mph or so possible this afternoon. The wind coupled with very low humidity will result in dry conditions and as such a Red Flag Warning has been issued. The elevated fire danger is cause for concern so please be careful.

Tonight, winds will be settling down and become calm after dark. Skies will be mostly clear with overnight lows around 40 degrees.

Keep an eye on the temperatures and wind speeds here.

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Lots of sun, unseasonably warm temperatures start Thornton’s workweek

Monday, April 27th, 2020 5:13am MDT

Monday is going to offer up some very nice weather for us with mercury readings well above normal. That is just the start though as by the end of the week we will be seeing summer-like temps.

For today, sunny skies start us off and will be with us through the morning. A few clouds will arrive later today but they won’t amount to much. High temperatures will be climbing to a high of around 80 degrees.

Tonight, a cold front will move through leading to increased clouds. Overnight lows will drop to the upper 40s.

Tomorrow will be cooler due to the front but after that, we see things warm up and get well into the 80s Thursday and Friday. Get more details in the extended forecast here.

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Thornton’s weekend starts out cool and damp, will warm up and dry out by the end

Friday, April 24th, 2020 5:10am MDT

A pretty typical period of weather ahead for us over the next few days. We do start out on the cool side with some showers but by the end of the weekend we will warm considerably.

Friday will be the most unsettled of the days. Mostly cloudy skies will be above with some periods of drizzle and light rain throughout. High temperatures will reach the mid to upper 50s. Tonight, mostly cloudy skies will be above and again there may be some periods of rain. Lows will drop to around 40 degrees.

Saturday will see mostly sunny skies above but still with a shower here and there. Highs will be in the low to mid-60s. Saturday night partly cloudy skies will be above with lows in the low 40s.

Sunday looks to be the warmest day of the period with highs in the mid-70s. It will be partly sunny and the afternoon brings just a slight chance for a thunderstorm. Have a great weekend and stay safe!

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Thursday brings breezy winds, better chance for showers

Thursday, April 23rd, 2020 5:18am MDT

Somewhat strong downslope flow will help to keep Thornton warm today but also will offer up breezy winds for much of the day. The afternoon brings a chance for a passing shower.

Mostly sunny skies start us off but clouds will be increasing with partly sunny skies being dominant most of the day. High temperatures will reach the mid-60s. Those breezy winds will be picking up through the morning and early afternoon before dying down around sunset.

Some scattered, light showers may be seen after noon and overnight. There isn’t a lot of moisture to work with so if we do see precipitation, it isn’t expected to be much.

Tonight, skies will be partly cloudy with lows around 40 degrees.

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Mild temperatures, slight chance for a PM shower on Wednesday

Wednesday, April 22nd, 2020 4:57am MDT

Today brings a near repeat of the weather conditions Thornton saw yesterday. Temperatures will again be above normal and we have just a slight chance for a shower in the afternoon.

Sunny skies start us off and will be with us through the morning. The afternoon will bring a few clouds but nothing too intrusive. High temperatures today will push close to the 70 degree mark.

Mid to late afternoon may see a shower move through but like yesterday, the chances are slim and likely to not amount to much more than virga. We will see some slightly breezy winds as well.

Tonight, skies will be mostly clear with lows in the low 40s.

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April 19 to April 25: This week in Denver weather history

Tuesday, April 21st, 2020 8:58am MDT

This Week in Denver Weather History

This week in Denver weather history is one to truly showcase the incredible variety of weather Colorado can receive. Major snow storms, high winds, warm temperatures in the 80’s and even three reports of tornadoes – one near Thornton 21 years ago – have all been seen this time of year.

From the National Weather Service:

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.

18-19

In 1884…a major storm dumped 13.8 inches of snowfall on downtown Denver. Most of the snow…10.0 inches… Fell on the 18th. Light rain on the early morning of the 18th changed to heavy snow at 8:00 am and became light after 2:00 pm but continued until 4:00 am on the 19th. The snow melted nearly as fast as it fell. There were only 3 inches on the ground early on the morning of the 19th.

In 1941…heavy snowfall totaled 8.4 inches over downtown Denver. Northeast winds were sustained to 17 mph.

In 1993…sporadic high winds occurred across metro Denver. Significant wind gusts included 97 mph at Rollinsville… 80 mph in southwest Boulder…and 55 mph at Stapleton International Airport. The strong winds snapped a pine tree top…about 15 feet long and 8 inches in diameter… Which crashed through the roof of a church in Evergreen…causing one thousand dollars in damage. Wind gusts of 50 to 60 mph caused structural damage to 3 homes under construction in Broomfield. Northwest winds gusted to 55 mph at Stapleton International Airport.

In 1995…the second spring storm of the month dumped heavy snow in the foothills. The upslope flow along with areas of thunder snow dropped 6 to 12 inches of snow in the foothills west of Denver and Boulder. Snowfall totaled 4.6 inches at the site of the former Stapleton International Airport…but most of the snow melted as it fell. East winds gusted to 29 mph at Denver International Airport on the 18th.

18-20

In 1966…sub-freezing temperatures caused thousands of dollars in damage to fruit trees across metro Denver. Minimum temperatures were in the teens each morning and failed to reach above freezing on the 19th. The low temperature of 13 on the 20th set a new record minimum for the date. Snowfall totaled 5.7 inches at Stapleton International Airport during the period.

19

In 1899…northwest winds were sustained to 48 mph with gusts as high as 60 mph in the city.

In 1941…the last snow of the season…0.4 inch…occurred… Marking the end of the shortest snow season…167 days. The first snow of the season…a trace… Occurred on November 4…1940.

In 1954…strong gusty winds raked metro Denver for most of the day producing some blowing dust. At midday…a severe dust devil was sighted in the Westwood area of southwest Denver.

In 1955…cold west winds at 52 mph with gusts as high as 69 mph were recorded at Stapleton Airport where blowing dust reduced the visibility to 1/2 mile.

In 1960…the second wind storm in 3 days produced sustained west winds up to 44 mph with gusts as high as 58 mph at Stapleton Airport. Winds were strong and gusty most of the day…but no damage was reported.

In 1963…the second windy day in a row produced west- northwest wind gusts to 52 mph at Stapleton Airport.

In 1971…a tornado occurred in the southwest corner of Weld County about 10 miles west-northwest of Brighton. The storm moved through a farm yard damaging equipment and structures. The strong tornadic winds lifted a stock tank over 2 fences into a corral 150 feet away. Later…a tornado touched down briefly west-southwest of Buckley Field…8 miles southeast of Stapleton International Airport. No damage was reported.

In 1985…high winds occurred in the foothills. Winds gusted to 97 mph atop Squaw Mountain in the foothills west of Denver. West winds gusted to 37 mph at Stapleton International Airport.

In 1987…a powerful cold front produced high winds and engulfed metro Denver in huge clouds of blowing dust that lowered the visibility to as little as 100 yards. The cold front generated winds as high as 72 mph at Brighton…67 mph in Thornton…and 54 mph at Stapleton International Airport. Winds of 50 to 70 mph were common along the Front Range from Denver north. The high wind gusts flipped a light plane taxiing at Stapleton International Airport…slightly injuring two people on board. The cold front dropped the temperature from a high of 80 degrees at 3:00 pm to a low of 33 degrees at midnight. Nearly an inch of snow…0.8 inch… Fell at Stapleton International Airport before midnight.

In 1988…a tornado touched down in Fort Lupton… Following a path 50 to 75 yards wide for 2 1/2 blocks. The twister damaged roofs on 2 schools and broke numerous windows; about 10 houses were damaged and several cars had windows blown out. Several trees were downed.

In 1989…winds were clocked to 68 mph in Wheat Ridge. Microburst winds gusted to 35 mph at Stapleton International Airport.

In 1996…high winds gusting from 70 to near 100 mph developed in the Front Range foothills and adjacent plains. Numerous power outages were reported as power lines and poles were downed. The high winds blew the chimney off the roof of a house in Westminster. Numerous homes received minor shingle damage. Some of the stronger wind gusts included: 98 mph at Jefferson County Airport in Broomfield…91 mph atop Squaw Mountain west of Denver…and 75 mph atop Table Mesa near Boulder. West northwest winds gusted to 45 mph at Denver International Airport.

In 2001…westerly Chinook winds… Gusting as high as 40 mph at Denver International Airport…prevented the low temperature from dropping below 51 degrees…setting a new record high minimum for the date. The high temperature of 77 degrees was not a record.

In 2005…severe thunderstorms produced large hail across metro Denver. Hail as large as 1 1/4 inches in diameter was measured in Arvada. Hail to 1 inch in diameter fell in Westminster…Northglenn… And Thornton. Hail to 7/8 inch was reported near Brighton…Barr Lake… And Castle Rock. Hail to 3/4 inch fell in Elizabeth and Broomfield and near Golden…Brighton… And Fort Lupton.

19-20

In 1892…rain on the 18th changed to snow on the 19th and totaled 6.0 inches over downtown Denver into the 20th. Total precipitation was 1.56 inches. North winds were sustained to 26 mph on the 19th.

In 1907…a major storm dumped 18.0 inches of snowfall in downtown Denver. Much of the heavy wet snow melted as it fell. The most snow on the ground was 7.0 inches at 6:00 pm on the 19th. North to northeast winds were sustained to 42 mph on the 19th and to 21 mph on the 20th. High temperatures were in the low to mid 30`s with low readings around 20.

» Click here to read the rest of April 19 to April 25: This week in Denver weather history

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Thornton’s Tuesday to offer temps a bit above normal, slight chance for a shower

Tuesday, April 21st, 2020 4:59am MDT

A pretty nice looking day ahead. We will see mercury readings just a bit warmer than normal and the afternoon and evening bring a slight chance for a shower / thunderstorm.

Mostly sunny skies start us off and will be with us much of the day with an increase in cloud cover in the late afternoon. High temperatures will top out in the mid-50s. The afternoon and evening may see a shower / thunderstorm develop although most activity should be to our south.

Tonight, chances for storms will be gone by about 9:00pm and skies will begin to clear. Overnight lows will drop to around 40 degrees.

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Seasonal temperatures, lots of sun for the start of Thornton’s workweek

Monday, April 20th, 2020 4:56am MDT

A nice-looking spring day ahead. We will have lots of blue above and temperatures will be right near average for the date.

A few clouds will be around early but those will quickly clear leading to sunny skies for much of the day. Conditions will be calm and dry. We will see high temperatures today in the low to mid-60s.

Tonight, partly cloudy skies will be above with overnight lows in the mid-30s.

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Severe Weather 101 – Severe Weather Awareness Week wrap up

Saturday, April 18th, 2020 5:00am MDT
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 18 2020

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

Tornadoes can even strike in mountain areas. In 2008 on August 23rd, this rope tornado struck Park County near Eleven Mile Reservoir. Image courtesy Jerry Bivens.

Tornadoes can even strike in mountain areas. In 2008 on August 23rd, this rope tornado struck Park County near Eleven Mile Reservoir. Image courtesy Jerry Bivens.

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)

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

This is one of the largest recorded hail stones which is more than 7 inches in diameter and fell in Nebraska in 2003. (NOAA)

This is one of the largest recorded hail stones which is more than 7 inches in diameter and fell in Nebraska in 2003. (NOAA)

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.

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.

 

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Denver sets a record low temperature for April 17; fifth cold temperature record of the week

Friday, April 17th, 2020 5:59am MDT

Record Cold Temperatures

Following yesterday’s snowstorm, cold air settled in and resulted in our fifth broken cold temperature record of the week.

As measured at Denver International Airport, the low temperature in Denver fell to 12 degrees this morning. That breaks the record low temperature for April 17th of 13 degrees set in 1901.

Today’s record cold is the fifth record set this week:

  • April 13 – Record low temperature of 15 degrees (17 degrees, 1933)
  • April 13 – Record low maximum temperature of 25 degrees (27 degrees, 1933)
  • April 14 – Record low temperature of 11 degrees (15 degrees, 1933)
  • April 16 – Record low temperature of 19 degrees (22 degrees, 2013 and previous years)
  • April 17 – Record low temperature of 12 degrees (13 degrees, 1901)
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