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Temperatures cool to seasonal norms, clouds increase a bit for Thursday

Thursday, April 25th, 2019 4:42am MDT

A cold front moved through last night and that will serve to change our weather a bit. Temperatures will be closer to normal and cloud cover will increase.

The day starts with mostly cloudy skies then we should see some gradual easing of the coverage. By mid-afternoon we should be seeing mostly sunny skies. Temperatures will top out today around 66 degrees, just a couple degrees above normal.

Tonight, partly cloudy skies will be above with lows in the mid-40s.

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April 21 to April 27: This Week in Denver Weather History

Wednesday, April 24th, 2019 1:35pm MDT
This week in Denver weather history

April 21 to April 27: This Week in Denver Weather History

While significant snow events become less frequent this time of year, our look back at this week in Denver weather history shows that they can still occur even toward the end of April. Thrown into the mix is a variety of spring severe weather including tornadoes and deadly lightning.

From the National Weather Service:

19-21

In 1984…a large snowstorm buried most of Colorado under a thick mantle of wet snow. Total snow amounts ranged from 10 to 20 inches across metro Denver and a whopping 20 to 40 inches in the adjacent foothills. The snow closed roads and damaged electrical transformers…causing numerous power outages. Nearly 14 inches (13.6) of snow fell at Stapleton International Airport where the combination of snow and wind closed all but one runway…resulting in the cancellation of many flights. Both I-70 and I-76 were closed to the east of Denver.

19-22

In 1933…a major storm dumped 16.8 inches of snowfall over downtown Denver when rain changed to snow during the early morning of the 20th and continued through midday of the 22nd. Most of the snow fell on the 21st. Due to melting… The most snow on the ground was 10.5 inches at 6:00 pm on the 21st. Before the snow started…a strong cold front on the evening of the 19th produced north winds sustained to 35 mph with gusts to 37 mph. The strong winds deposited a thin layer of dust on the city. North to northwest winds were sustained to 31 mph with gusts to 35 mph on the 20th and to 29 mph with gusts to 32 mph on the 21st.

20-22

In 1957…strong and gusty south to southeast winds raked metro Denver each day. The strongest wind gust of 55 mph occurred on the 21st when blowing dust briefly reduced the visibility to 3/4 mile at Stapleton Airport.

20-23

In 1989…unusually warm weather resulted in several daily temperature records being broken in Denver. The high temperature of 89 degrees on the 21st exceeded the record maximum for the month at that time. Daily record high temperatures were either exceeded or equaled with 83 degrees on the 20th…88 degrees on the 22nd…and 85 degrees on the 23rd. The low temperature of 55 degrees on the 22nd equaled the record high minimum for the date.

21

In 1885…rain changed to snow during the early morning and was the heaviest snow of the season. Total snowfall was estimated at 8.0 inches over downtown Denver…but the snow melted rapidly on the ground as it fell. However… The weight of the snow…as well as northwest winds sustained to 29 mph downed telegraph and telephone wires. Several large branches of trees were also broken by the weight of the snow. Precipitation totaled 1.01 inches from the storm.

In 1887…west winds were sustained to 47 mph.

In 1932…the temperature dipped to a low of only 60 degrees… The all-time record high minimum for the month.

In 1988…a small tornado was observed by National Weather Service employees about 3 miles northwest of Thornton. It was on the ground for about 2 minutes. No damage was reported. Later…lightning struck two 14-year-old girls on a softball field in Westminster. One was killed…while the other suffered moderate injuries. Northwest winds gusted to 44 mph at Stapleton International Airport behind a cold front.

In 2010…severe thunderstorms produced large hail…strong winds and a tornado across parts of Adams…Arapahoe… Elbert…and weld counties. The hail…up to 1.50 inches in diameter…came down so heavy along parts of I-70 and I-76 that snowplows had to be called out to remove it. Numerous vehicles were damaged by hail. In weld County…very heavy rain and hail accompanied thunderstorm winds up to 75 mph. Hail up to 1.50 inches was reported near Bennett; 1.25 inches…5.3 miles east of Englewood; 1.0 inch size hail near Buckley Field; with 0.88 inch size hail near Boulder. A weak tornado touched down briefly in Elbert County…about 9 miles southwest of Deer Trail…but did no damage. Several minor accidents were reported with snowpacked and slick road conditions along with very low visibilities. Minor street flooding was reported in southeast Aurora. Denver International Airport recorded 0.30 inches of rainfall. Also…a peak wind gust to 36 mph from the southeast was observed at the airport.

21-22

In 1910…north winds were sustained to 45 mph behind a cold front. Rainfall totaled 0.63 inch.

In 1923…snowfall of 2.0 inches in the city was the only snow of the month and the last measurable snow of the season. Northwest winds were sustained to 25 mph on the 21st.

In 1952…heavy snowfall totaled 7.6 inches at Stapleton Airport. The storm was accompanied by north winds gusting to 33 mph.

In 2001…the second major snow storm in 11 days moved into metro Denver with blizzard conditions developing again across the plains to the northeast of Denver. Snowfall amounts ranged up to 9 inches in metro Denver with up to 23 inches in the foothills. Northwest winds were sustained at 20 to 30 mph with gusts as high as 36 mph at Denver International Airport which was again shut down for nearly an hour by power outages on the 22nd. The outages affected lighting in the concourses…train operations…de-icing and refueling operations…flight information displays…and security screenings. Navigational aids were also affected… Resulting in the cancellation of 58 arriving and departing flights which stranded about 5000 passengers. Across metro Denver storm totals included: 9 inches at Eldorado Springs; 7 inches in Boulder; 6 inches at Ken Caryl…Northglenn and near Sedalia; and 5 inches in Arvada and Morrison. Only 1.7 inches of snow were measured at the site of the former Stapleton International Airport. In the foothills snow totals included: 23 inches near Fritz Peak south of Rollinsville…17 inches near Jamestown…16 inches near Blackhawk…14 inches in Coal Creek Canyon…13 inches at Idaho Springs and near Nederland…11 inches at Aspen Springs…and 10 inches near Bergen Park.

21-23

In 1999…a spring snowstorm dumped heavy snowfall over metro Denver and in the foothills. Nearly 3 feet of snow fell in the foothills with over a foot in the city. The heavy wet snow downed power lines in Douglas and Elbert counties. Scattered outages were reported at Parker…Franktown… Sedalia…and Castle Rock. Some residents were without electricity for as long as 20 hours. The inclement weather was blamed…at least in part…for several traffic accidents along the I-25 corridor between Denver and Castle Rock. Snowfall totals included: 32 inches at Idaho Springs; 31 inches on Crow Hill; 29 inches near Evergreen; 26 inches at Chief Hosa and Coal Creek Canyon; 25 inches at Bailey; 24 inches at Floyd Hill; 23 inches at Conifer…Genesee…Golden Gate Canyon…North Turkey Creek…and Pine Junction; 13 inches at Broomfield and near Sedalia; 12 inches in Boulder; 11 inches at Louisville and Parker; and 9 inches at the site of the former Stapleton International Airport.

In 2004…heavy snow fell across metro Denver…when low level upslope conditions developed against the foothills and Palmer Divide. Snowfall totals included: 18 inches in the foothills southwest of Boulder…17 inches at Intercanyon and near Conifer…10 inches near Blackhawk and Parker…9 inches at Castle Rock and near Sedalia…7 inches in centennial… Littleton…and near lone tree. Elsewhere across metro Denver…snowfall generally ranged from 2 to 5 inches. Snowfall was 4.7 inches at Denver Stapleton. Northwest winds gusted to 35 mph at Denver International Airport on the 21st.

» Click here to read the rest of April 21 to April 27: This Week in Denver Weather History

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Wednesday brings a healthy dose of sun, unseasonably warm temperatures

Wednesday, April 24th, 2019 4:57am MDT

This will be the kind of spring day just about everyone can love. Sunny skies, calm conditions very comfortable temperatures. What isn’t there to like?

The day starts off with clear skies and then we will see a few clouds build this morning and into the afternoon but nothing too intrusive. Temperatures will top out in the low to mid-70s. Winds will be light and out of the southwest this morning shifting to come from the northeast later.

This evening and overnight, partly clear skies will be above. There is just the slightest chance for some isolated thunderstorm activity in the evening but we aren’t expecting to see much.

Lows tonight will be in the mid-40s.

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Clouds decrease, temperatures warm up for Thornton’s Tuesday

Tuesday, April 23rd, 2019 4:57am MDT

Following a cool, damp day yesterday, we begin a rebound that will see temperatures warm, conditions dry out and last through the weekend. Today will start things off with temps near normal and clearing skies.

The day starts with a good bit of cloud cover but that will ease as the morning progresses. The afternoon will enjoy mostly sunny skies. Temperatures today will top out in the mid-60s, a couple degrees warmer than the average high for the date of 63 degrees.

Tonight, skies remain mostly clear with lows in the low to mid-40s. Enjoy

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Thornton’s workweek starts cool and damp, warmer weather awaits for rest of the week

Monday, April 22nd, 2019 4:58am MDT

With low pressure to our northeast and southwest, we find ourselves sandwiched in between two systems. Cooler than normal temperatures and a bit of rain will be the result for today.

Cloudy skies will be above for much of the day with some fog possible this morning. Spots of light rain and drizzle will be seen early then we should dry out entirely by noon. Today’s high temperature will be near the 50 degree mark.

Tonight, mostly cloudy skies will be above with lows in the upper 30s.

Looking at the rest of the week, above normal temperatures will be the rule with dry conditions for the majority of the time. Get a closer look in the extended weather forecast here.

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National Weather Service announces storm spotter training dates for 2019

Saturday, April 20th, 2019 5:01am MDT

On June 3, 1981 a tornado struck Thornton in what is the worst twister to have struck the Denver metro area. Are you ready should disaster strike again? Image courtesy the City of Thornton archives.

Severe weather is a fact of life in Colorado – from blizzards to tornadoes we can and do see it all.  Each year the weather is responsible for claiming lives in our state and across the nation and the threat is very real.  Storm spotter training allows you to learn how to protect yourself and your family while providing a public service.

Education is key to knowing how to protect you and your family.  Whether you want to be an official storm spotter or maybe just want to learn more about severe weather, storm spotter training can provide you an incredible opportunity to learn.

The National Weather Service Denver / Boulder office has announced a series of Skywarn storm spotter training dates for Colorado for the 2019 season.

The storm spotter program is a nationwide program with more than 280,000 trained spotters.  These volunteers report weather hazards to their local National Weather Service office providing vital information when severe strikes.  Data from spotters include severe wind, rain, snow measurements, thunderstorms and hail and of course tornadoes.

Storm spotters are part of the ranks of citizens who form the Nation’s first line of defense against severe weather. There can be no finer reward than to know that their efforts have given communities the precious gift of time–seconds and minutes that can help save lives.

By completing one of these training classes you can become an official storm spotter.  When severe weather strikes, you can report it by calling a special toll free number or submit your report via the National Weather Service’s website.

These are great sessions for anyone wanting to learn more about the severe weather we experience in Colorado, whether you want to be an official spotter or not.  All training is free.  Topics include:

  • Basics of thunderstorm development
  • Fundamentals of storm structure
  • Identifying potential severe weather features
  • Information to report
  • How to report information
  • Basic severe weather safety

To learn more about the program, see here: http://www.crh.noaa.gov/bou/awebphp/spotter.php

Below are the dates, times and locations announced thus far.  The embedded calendar should automatically update with new dates and changes but be sure to check the National Weather Service site for the latest.


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Severe Weather 101 – Severe Weather Awareness Week wrap up

Saturday, April 20th, 2019 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 20 2019

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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Severe Weather 101 – Lightning and lightning safety

Friday, April 19th, 2019 5:08am MDT
This is NOT the time to be outside. (michaeljames / FLICKR)

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.

» Click here to read the rest of Severe Weather 101 – Lightning and lightning safety

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Thornton’s weekend starts out pleasant, unseasonably warm; will end cooler and wetter

Friday, April 19th, 2019 4:55am MDT

A bit of a mixed bag of weather ahead for us over the three day period. Friday and Saturday will be gorgeous with very mild temperatures but a storm system will cool it down and dampen things come Sunday.

For today, look for sunny skies throughout the day with calm conditions. Highs today will top out in the mid-70s. Tonight, mostly clear skies will be above with lows in the low to mid-40s.

Saturday will be the warmest day of the period with highs right near the 80 degree mark. Mostly sunny skies will be above and conditions calm. Saturday night cloud cover will increase with lows in the mid-40s.

Sunday we will see the effects of the storm. Some light showers may be possible early with coverage then becoming more widespread and a bit heavier in the afternoon through the evening. Mostly cloudy skies will be above with highs right near the average for the date of 63 degrees.

All in all, not too bad. Have a great weekend.

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Severe Weather 101 – Hail and Wind

Thursday, April 18th, 2019 7:06am MDT
Straight line winds can be as damaging as a tornado. This image is from a park in Tennessee. (NWS)

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.

» Click here to read the rest of Severe Weather 101 – Hail and Wind

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