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Chilly temperatures, calm weather conditions for Christmas Day in Thornton

Monday, December 25th, 2017 5:56am MDT

An uneventful, but chilly, day ahead for us. Temperatures will be similar to yesterday and we will see a bit more cloud cover.

The day starts with partly cloudy skies and we will see some slow, gradual easing of the coverage as the morning progresses. This afternoon should be partly sunny. Winds will be light and out of the northeast. Temperatures will top out today in the mid-20s as we feel the effects of the snow on the ground as well as some cold air filtering in from the northeast.

Tonight, skies remain partly clear with temperatures becoming quite cold in the overnight hours. Look for lows in the single digits.

We wish you all a very merry Christmas and a blessed New Year!

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December 24 to December 30: This week in Denver weather history

Sunday, December 24th, 2017 5:37am MDT
This Week In Denver Weather History

December 24 to December 30: This week in Denver weather history

Christmas Day is normally a relatively quiet day in terms of the weather but the week between it and New Year’s can be quite eventful. Among the highlights are a prolonged period of sub-zero temperatures that lasted nearly five days. Just 11 years ago a blizzard struck the region that snarled holiday travel on the air and the ground.

From the National Weather Service:

17-24

In 1924…a prolonged cold spell occurred after mild temperatures during the first half of the month. Most low temperatures dipped below zero with the coldest reading of 15 degrees below zero occurring on the 24th. The high temperature of only 5 degrees on the 18th was a record low maximum for the date.

18-24

In 1998…a vigorous cold front with north winds gusting as high as 38 mph at Denver International Airport on the 18th dropped temperatures from a high of 51 degrees to a low of just 6 degrees before midnight. The arctic air mass that settled over metro Denver produced intermittent light snow and a week-long protracted cold spell that caused low temperatures to plunge well below zero for 6 consecutive nights. The coldest temperature was 19 degrees below zero on the morning of the 22nd. High temperatures climbed only into the single digits on 4 consecutive days…from the 19th through the 22nd. At least 15 people…mostly homeless… Were treated for hypothermia at area hospitals. The bitter cold weather was responsible…either directly or indirectly… For at least 5 fatalities. Three of the victims died directly from exposure. The cold weather also caused intermittent power outages. Following the cold snap… Thawing water pipes cracked and burst in several homes and businesses…causing extensive damage. Only one temperature record was set. The high temperature of only 7 degrees on the 19th set a record low maximum for the date.

20-25

In 1983…an extremely bitter cold spell occurred. The temperature remained below zero for 115 hours in Denver… The longest sub-zero period on record. The mercury dipped to 21 degrees below zero on the 21st…the coldest recorded temperature in over 20 years. The cold was accompanied by winds that plunged chill factors to 50 to 70 degrees below zero. Two people froze to death in Denver; both were found outside dead of exposure. Numerous cases of frostbite were reported. Hundreds of water pipes broke from the intense cold…water mains and natural gas lines also fractured…and electricity consumption reached record levels. Light snow totaling 5.8 inches fell at times…and holiday traffic was delayed at Stapleton International Airport for several hours. Eight daily temperature records were set at the time. The all-time record low maximum temperature for the month of 8 degrees below zero on the 21st still stands today. Other temperature records still standing include record low maximum temperatures of 5 degrees below zero on both the 22nd and 23rd and 4 degrees below zero on the 24th.

22-24

In 2009…A winter storm produced moderate to heavy snow across parts of the Front Range and adjacent plains. In the foothills…storm totals included: 11.5 inches near Eldorado Springs…10 inches…3 miles southeast of Pinecliffe; 9 inches at Genesee…2 miles southwest of Golden and Ken Caryl; 8 inches…3 miles west of Jamestown and White Ranch Open Space; 7 inches…4 miles east-northeast of Nederland. Across the Urban Corridor and adjacent plains…storm totals included: 9 inches…2 miles west of Parker; 8 inches at Watkins; 7 inches…2 miles west-southwest of Byers…12 miles southwest of Buckley AFB and 3 miles northeast of Parker. At Denver International Airport…6.1 inches of snowfall was observed.

23-24

In 1907…winds nearly as strong as a hurricane raked Boulder and areas north of Denver…killing one person and injuring others. Property damage was minor.

In 1973…a pre-Christmas blizzard…the second in 5 days… Produced strong winds and dumped heavy snow across metro Denver. Nearly a foot…11.8 inches…of snow fell at Stapleton International Airport where north winds gusting from 30 to 40 mph produced much blowing snow. The strong winds whipped the snow into 2- to 4-foot drifts…closing many roads and airports. About 10 thousand people were stranded at Stapleton International Airport for up to 24 hours.

In 1978…wind gusts to 90 mph on the 23rd and 73 mph on the 24th were recorded in Boulder. A townhouse under construction was severely damaged by the winds. At Stapleton International Airport…west winds gusted to 37 mph on the 23rd and northwest winds gusted to 35 mph on the 24th.

In 1987…a snowstorm assured a white Christmas for metro Denver…where 4 to 8 inches fell. Amounts in the foothills ranged from 10 to 18 inches. Snowfall totaled 3.9 inches at Stapleton International Airport…where north winds gusted to 32 mph on the 23rd.

20-25

In 1983…an extremely bitter cold spell occurred. The temperature remained below zero for 115 hours in Denver… The longest sub-zero period on record. The mercury dipped to 21 degrees below zero on the 21st…the coldest recorded temperature in over 20 years. The cold was accompanied by winds that plunged chill factors to 50 to 70 degrees below zero. Two people froze to death in Denver; both were found outside dead of exposure. Numerous cases of frostbite were reported. Hundreds of water pipes broke from the intense cold…water mains and natural gas lines also fractured…and electricity consumption reached record levels. Light snow totaling 5.8 inches fell at times…and holiday traffic was delayed at Stapleton International Airport for several hours. Eight daily temperature records were set at the time. The all-time record low maximum temperature for the month of 8 degrees below zero on the 21st still stands today. Other temperature records still standing include record low maximum temperatures of 5 degrees below zero on both the 22nd and 23rd and 4 degrees below zero on the 24th.

24

In 1876…the all-time lowest recorded temperature in December… 25 degrees below zero…occurred. The same temperature was also reached on December 22…1990.

In 1907…west winds were sustained to 43 mph. The Chinook winds warmed the temperature to a high of 58 degrees.

In 1908…west Bora winds sustained to 49 mph produced a high temperature of 42 degrees. A trace of snow fell.

In 1977…wind damaged temporary wooden structures at construction sites in Denver. Several trees were blown over…causing damage to houses and cars. Power outages occurred in northwest Denver. Some chimneys were blown off a house in the Ken Caryl Ranch area. Wind gusts to 70 mph were reported in Boulder…and northwest winds gusted to 53 mph at Stapleton International Airport.

In 1982…on Christmas eve… one of the worst blizzards of all time dumped 24 to 34 inches of snow across metro Denver. The heaviest official one-day snow amount in the city’s history…23.6 inches…brought traffic to a standstill and completely closed Stapleton International Airport on Christmas day. Boulder received 18 to 24 inches of snow. Two feet of snow buried Parker and Sedalia to the south of Denver. Weather conditions during the storm were brutal. Visibility at Stapleton International Airport was reduced to 1/4 mile or less for 17 consecutive hours. Sustained winds of 25 mph or more persisted for 15 consecutive hours. Gusts over 40 mph were recorded during 12 different hours. The highest recorded wind gust was 51 mph. The howling winds blew snow into drifts 4 to 8 feet high…paralyzing all modes of transportation. All highways leading out of Denver were closed. Stapleton International Airport was closed for 33 hours and operated on only a limited schedule for days afterward. Thousands of travelers were stranded and failed to reach their destinations in time for Christmas. Many wayward commuters and shoppers were forced to take refuge in shopping malls… Which remained open when workers themselves became stranded. Mall restaurants served food to the refugees. The storm prevented most people in the area from spending Christmas day with family and friends. In metro Denver…three people died as a direct result of the blizzard: a 60-year-old man died of hypothermia on his screened in back porch; a 66 year old man froze to death after falling into a drift a few feet from his home; a 34- year-old man froze to death just east of Denver after abandoning his 4-wheel drive vehicle which became stuck in the snow. With the heavy snow and wind chill temperatures of 20 to 30 degrees below zero…there were many injuries from frostbite and falls. Damage from the blizzard was varied and widespread. A number of roofs collapsed under the weight of the heavy snow; greenhouses received the greatest damage when the heavy snow shattered glass roofs… Allowing cold air to freeze the tender plants inside. Total damage to greenhouses and plants alone was estimated at 5 million dollars. The strong winds with the storm damaged many fences and caused numerous power outages. Last minute Christmas shoppers were literally left out in the cold and snow…as the storm made travel increasingly difficult during the day. Merchants lost significant income from the last shopping day before Christmas. Overall…businesses lost an estimated 500 million dollars due to the blizzard. In metro Denver…seven million dollars were spent for snow removal…three million dollars in the city of Denver alone. This expenditure did not prevent a subsequent snow removal controversy. Once the major streets were made passable…cold late December and January temperatures prevented much melting. Icy and snowpacked side streets and parking lots became rutted… Making travel around metro Denver difficult for nearly a month after the storm. In fact…snow cover of an inch or more lasted for 48 consecutive days after the storm… Through February 9…1983. This is the third longest period of snow cover on record in the city. The period would have been longer…but no significant snow fell for more than 2 months after the storm.

24-25

In 1891…heavy snowfall of 7.0 inches in downtown Denver provided a white Christmas. Most of the snow…6.5 inches… Fell on the 24th. Northwest winds were sustained to 30 mph with gusts to 40 mph on the 24th.

In 1894…snow began falling during the evening of the 24th… Ended during the early afternoon of the 25th…and totaled 6.4 inches in downtown Denver. Northwest winds were sustained to 26 mph with gusts to 30 mph on the 24th. The maximum snow depth on the ground was 5 inches. The high temperature was only 18 degrees on the 25th after a low of 8 degrees.

In 1980…strong Chinook winds of 50 to 60 mph occurred in the foothills with a wind gust to 90 mph recorded at Wondervu. West winds gusted to 33 mph at Stapleton International Airport on the 25th.

In 1997…a relatively rare Christmas snowstorm blanketed much of northeastern Colorado. Snowfall in and near the Front Range foothills and south of metro Denver ranged from 5 to 8 inches. Elsewhere…new snow accumulations were generally 1 to 3 inches. Snowfall totaled only 1.5 inches at the site of the former Stapleton International Airport. North winds gusted to 29 mph at Denver International Airport on the 24th.

In 2012…a winter-like weather moved into northeast Colorado on Christmas Eve as an upper level trough and a strong cold front moved through the region. At Denver International Airport…2.5 inches of snow fell from Christmas Eve through Christmas morning.  The high temperatures on Christmas Day only reached 16 degrees…which was the coldest day of the month.

25

In 1873…northwest winds were sustained to 36 mph during the morning and to 48 mph in the evening. The Chinook winds warmed the temperature to a high of 53 degrees.

In 1883…gusty very strong winds raked Boulder…causing 11 hundred dollars in damage.

In 1985…Table Mesa in Boulder was buffeted by wind gusts to 68 mph.

In 1993…occasional high winds occurred over portions of the higher foothills west of Boulder and Denver. A wind gust to 87 mph was recorded on squaw mountain…and a gust to 83 mph occurred at Rollinsville. Northwest winds gusted to 35 mph at Stapleton International Airport.

In 2007…a winter storm brought heavy snow to the Front Range of Colorado. The heaviest snow fell near the foothills of Boulder…Douglas and Jefferson counties. The snow caused accidents throughout the Denver metropolitan area. Gusty winds produced snow drifts from 2 to 3.5 feet in depth. Total snowfall for the calendar day in Denver was 7.8 inches…setting a new record for Christmas Day. The measurement was taken at the former Stapleton International Airport; the previous record was 6.2 inches… Set in 1894. Storm totals in the Front Range foothills included: 13.5 inches at Coal Creek Canyon; 12 inches…5 miles east-southeast of Aspen Park; 11 inches; 6 miles southwest of kassler; 10.5 inches at Eldorado Springs. Elsewhere…storm totals ranged from 5 to 10 inches. In the urban corridor storm totals included: 9 inches near Elizabeth; 8 inches in southwest Denver…Highlands Ranch…Marston Reservoir and Wheat Ridge; 7.5 inches in Arvada; 7 inches in Centennial and Lakewood; 6.5 inches in Aurora and 8 miles southeast of Watkins; 6 inches in Boulder…Englewood and Parker. Elsewhere…storm totals ranged from 3 to 5 inches.

25-26

In 1904…after a warm Christmas Fay with a high temperature of 50 degrees…a late day cold front plunged temperatures to a low of 7 degrees…produced northeast winds sustained to 40 mph with gusts to 54 mph…and produced 5.2 inches of snow overnight for a late white Christmas. The maximum temperature on the 26th was only 16 degrees.

In 2014…a winter storm brought a rare Christmas Day snowfall to the Front Range Foothills and Urban Corridor…from the afternoon of the 25th to the evening of the 26th. Storm totals included: 12.5 inches…4 miles west of Boulder; 12 inches…4 miles southwest of Eldorado Springs and 4 miles south of Golden; 11 inches at Genesee; 10 inches near Allenspark…5 miles west of Chatfield Reservoir… 5 miles southwest of Golden and near Tiny Town; 8 inches in Lakewood and Louisville; 7.5 inches in Niwot; 7 inches in Longmont; with 6 inches in Broomfield and Frederick. At Denver International Airport…5.1 inches of snowfall was observed.

25-31

In 1980…temperatures were unusually warm during the week between Christmas and New Year’s. High temperatures for the week ranged from the mid-50’s to the mid-70’s. Four temperature records were set. Record highs occurred on the 26th with 68 degrees…the 27th with 75 degrees…and the 30th with 71 degrees. A record high minimum temperature of 41 degrees occurred on the 27th.

26

In 1877…heavy snow fell during the early morning and totaled nearly 6 inches. Precipitation from melted snow was 0.58 inch. After the snowfall…a number of sleighs were seen on the city streets.

In 1879…after a morning low of 4 degrees below zero… The temperature climbed to a high of 57 degrees in the city.

In 1907…west winds were sustained to 40 mph. The Chinook winds warmed the temperature to a high of 62 degrees.

In 1949…west winds gusted to 50 mph at Stapleton Airport.

In 1998…intense…but localized…downslope high winds developed near Wondervu in the foothills southwest of Boulder. Winds frequently gusted to 100 mph with a highest reported wind gust to 104 mph. West winds gusted to only 43 mph at Denver International Airport.

» Click here to read the rest of December 24 to December 30: This week in Denver weather history

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Video: Thornton’s surprising pre-Christmas snow

Sunday, December 24th, 2017 5:30am MDT

We were expecting snow but not quite as much as received.  The storm that hit yesterday evening delivered a respectable 3.5 inches to Thornton as snow bands were quite strong and aided by upslope. Temperatures early this morning dipped well into the single digits, our coldest readings since January 7.

The time lapse video below captures four hours of the event as it started and then began to taper off.

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Thornton’s holiday weekend to feature largely seasonal conditions

Friday, December 22nd, 2017 4:32am MDT

Not a lot of drama in our weather for the four-day period through Christmas. For the most part we will remain dry and calm with temperatures not too far from normal.

Friday looks to be one of the most pleasant days as we are in between storm systems. Look for plenty of sun and highs in the mid to upper 30s. Tonight into Saturday morning, cloud cover will increase with lows in the teens.

Saturday brings a bit more active weather. We will have a good bit of cloud cover and the PM hours offer up a slight chance for light snow. Very light, if any, accumulation is expected. Temperatures overnight Saturday into Sunday morning will be quite cold with readings into the single digits.

Sunday looks in many ways to be a day like today although with a bit more cloud cover. Look for mostly sunny skies, highs in the mid to upper 30s.

Christmas will not, unfortunately, be a white one for us. Conditions will be dry with mostly sunny skies and temperatures will be around the 40 degree mark.

From our family to yours, we wish you all very merry Christmas and blessed New Year!

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First day of winter brings cold and snow to Thornton

Thursday, December 21st, 2017 5:13am MDT

Mother Nature can have impeccable timing sometimes. With the winter solstice and the changing of astronomical seasons occurring today, she is delivering us much colder temperatures and a bit of snow.

As expected, light snow has developed early this morning and will continue through mid-morning before slowly easing through the rest of the day. This isn’t a particularly strong system but we may very well see 1 to 3 inches out it, perhaps less depending on how it all plays out.

Probably the most notable feature will be the 40 degree drop in high temperatures from yesterday. Temperatures will be only in the mid-20s today.

Tonight skies will clear and in the wake of the cold front, aid in sending the mercury way down. Overnight lows will dip to near 10 degrees.

All the latest on our Winter Weather Briefing Page here.

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Winter Solstice brings shortest day of the year, change of seasons

Wednesday, December 20th, 2017 8:31am MDT
The Winter Solstice

Winter officially begins at 9:28am MST on Thursday, December 21, 2017. (NOAA)

Astronomical winter arrives in Thornton Thursday morning and with the solstice also comes the shortest day of the year.  Mother Nature as well appears set to bring in winter with a bit of a bang and a change in our recent mild, dry weather pattern.

Winter officially begins at 9:28am MST on Thursday, December 21.

The Winter Solstice occurs when the North Pole is tilted at its furthest from the sun – 23.5 degrees away. This results in the shortest day of the year in the Northern Hemisphere.

Here in Denver, with sunrise at 7:17am and sunset at 4:38pm, our day Thursday will be 9 hours, 21 minutes and 16 seconds long. The following day, Friday, it will be three seconds longer and each day from now through to the Summer Solstice in June will get gradually longer as well.

While we have a short day today, it is nothing like what will be experienced in the Arctic Circle.  Areas north of there to the North Pole will have no direct sunlight at all.  Conversely, areas south of the Antarctic Circle toward the South Pole will have 24 hours of daylight and have a midnight sun.

Did you know that there is a difference between the astronomical seasons that we are discussing here and meteorological seasons?

Meteorological seasons differ slightly and are geared toward matching the calendar with the annual temperature cycle. This is done primarily for meteorological observing and forecasting and in many ways it is more logical than the astronomical seasons.

For the Northern Hemisphere, the meteorological spring covers the months of March, April and May. Summer brings the hottest months of the year and so meteorological summer is June, July and August. Meteorological fall then is September, October and November followed by the coldest months of December, January and February as meteorological winter.

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

Wednesday, December 20th, 2017 6:00am MDT
This Week In Denver Weather History

December 17 to December 23: This Week in Denver Weather History

Looking back at Denver weather history, it is readily apparent that the week leading up to Christmas has historically been a very eventful one. There are certainly many of the snow and wind events we would expect to see. Most notable however are the major winter storms like the pre-Christmas storm of 2006.

From the National Weather Service:

2-17

In 1939…more than 2 weeks of unseasonably warm weather made the month the 3rd warmest on record. Seven daily temperature records were set…including the all time record high temperature for the month of 79 degrees on the 5th. Daytime highs were balmy with 14 days in the 60’s and 70’s. Low temperatures dipped to freezing or below on only 5 days. The period was dry with only a trace of snow on the 12th.

16-17

In 1908…heavy snowfall totaled 7.9 inches in downtown Denver where north winds were sustained to 20 mph on the 17th. Temperatures were in the teens and 20’s.

In 1939…low temperatures of 49 degrees on the 16th and 43 degrees on the 17th were record high minimums for the dates. High temperatures of 65 on the 16th and 72 on the 17th were not records.

In 1980…Chinook winds blew through the night in Boulder with a peak reported gust to 75 mph. Northwest winds gusted to 30 mph at Stapleton International Airport on the 17th. The strong Chinook winds warmed temperatures to record daily highs of 70 degrees on the 16th and 73 degrees on the 17th.

17

In 2000…high winds gusting from 60 to 74 mph howled across the northeast plains of Colorado. In Parker where winds gusted to 60 mph…a 20-foot by 40-foot piece of roof was ripped from a building. West winds gusted to 53 mph at Denver International Airport. This was the highest wind gust of the month at the airport. An intense…but very localized wind gust to 112 mph was measured near Georgetown Lake in the foothills west of Denver.

 

17-24

In 1924…a prolonged cold spell occurred after mild temperatures during the first half of the month. Most low temperatures dipped below zero with the coldest reading of 15 degrees below zero occurring on the 24th. The high temperature of only 5 degrees on the 18th was a record low maximum for the date.

18

In 1901…north winds were sustained to 52 mph with gusts to 58 mph behind an apparent cold front.

In 1973…a brief blizzard dumped heavy snow across metro Denver. Snowfall totaled 9.2 inches at Stapleton International Airport where north winds gusting to 53 mph produced much blowing snow. The storm forced many schools and businesses to close.

In 1996…a homeless man in Denver was found unconscious in his car suffering from exposure. The man’s body temperature was only 85 degrees when he was discovered. He died several hours later. Early morning temperatures had dipped to 9 degrees below zero.

In 1999…high winds were reported for a brief time in the foothills. Winds gusted to 72 mph in Golden Gate Canyon and to 71 mph at the National Center for Atmospheric Research in the foothills southwest of Boulder. West winds gusted to only 39 mph at Denver International Airport where the temperature warmed to a high of 53 degrees.

In 2002…only a trace of snow fell at the site of the former Stapleton International Airport. This…along with the trace of snow on the 5th…was the only snow of the month…ranking the month the 2nd least snowiest on record.

18-19 In 2012…a storm system brought moderate to heavy snow to the mountains and foothills west of metropolitan Denver and blizzard conditions to plains east of Denver metro area. The combination of snow and wind reportedly reduced visibility to just a few hundred feet at times…and resulted in several road closures including Interstate 70 east of Aurora. East of Denver gusty northerly winds ranged from 35 to 55 mph produced extensive blowing and drifting snow…ranging from 1 to 4 feet in depth. Storm totals ranged from 3 to 5 inches. In the mountain and foothills…the heaviest snowfall occurred along and north of I-70 and included: 12 inches at Genesee…9 inches near Eldorado Springs; 8.5 inches at Coal Creek Canyon…8 inches near Evergreen… with 6 inches at Eldora Ski Area…Idaho Springs… Gross Reservoir and Nederland. At Denver International Airport…1.7 inches of snowfall was observed. In addition…a peak wind gust to 35 mph was observed from the north on the 19th.

18-21

In 2010…a winter storm produced a 4-day period of moderate to heavy snow in the mountains. The combination of strong wind and heavy snow forced the closure of several mountain passes due to the threat of avalanches. The Amtrak train route… Which runs from Denver to California…was rerouted through Wyoming when Union Pacific closed its tracks along Interstate 70. Numerous accidents forced the closure of I-70 at times. The wind gusted to 60 mph over the higher mountain passes. Storm totals in the ski areas west of Denver ranged from 16 to 32 inches.

18-24

In 1998…a vigorous cold front with north winds gusting as high as 38 mph at Denver International Airport on the 18th dropped temperatures from a high of 51 degrees to a low of just 6 degrees before midnight. The arctic air mass that settled over metro Denver produced intermittent light snow and a week-long protracted cold spell that caused low temperatures to plunge well below zero for 6 consecutive nights. The coldest temperature was 19 degrees below zero on the morning of the 22nd. High temperatures climbed only into the single digits on 4 consecutive days…from the 19th through the 22nd. At least 15 people…mostly homeless… Were treated for hypothermia at area hospitals. The bitter cold weather was responsible…either directly or indirectly… For at least 5 fatalities. Three of the victims died directly from exposure. The cold weather also caused intermittent power outages. Following the cold snap… Thawing water pipes cracked and burst in several homes and businesses…causing extensive damage. Only one temperature record was set. The high temperature of only 7 degrees on the 19th set a record low maximum for the date.

19

In 1913…post-frontal heavy snowfall totaled 8.5 inches over downtown Denver. North winds were sustained to only 16 mph.

In 1994…an intense pacific storm system and associated cold front moved across Colorado early in the day. Strong downslope winds buffeted the Front Range eastern foothills. The highest wind gust recorded was 92 mph at Rocky Flats in northern Jefferson County. Most of the wind gusts during the day ranged from 63 to 86 mph with lighter gusts of 40 to 58 mph on the northeast plains. The strong winds downed power lines and poles in south Lakewood…causing power outages to 2400 homes. Other small power outages and surges occurred across metro Denver. Northwest winds gusted to 43 mph at Stapleton International Airport.

19-20

In 1982…high winds buffeted the eastern foothills. At midday on the 19th…gusts of 75 to 80 mph were recorded in the Table Mesa area of Boulder. A gust to 62 mph was clocked in Boulder on the evening of the 20th.

In 1989…strong winds howled at mountain top level in clear creek and Gilpin counties. Speeds reached 97 mph on the summit of Squaw Mountain and 84 mph one mile south of Rollinsville. Northwest winds gusted 35 mph at Stapleton International Airport on the 20th.

19-23

In 1990…a surge of very cold arctic air invaded metro Denver. Many temperature records were broken as the mercury remained at or below zero for 85.5 hours at Stapleton International Airport…making it the third longest period of subzero readings in 118 years of record keeping. On the morning of the 22nd…the mercury plunged to 25 degrees below zero…which equaled the all time record low temperature for the month set on December 24…1876. In the foothills southwest of Denver at tiny town…the mercury plunged to 33 degrees below zero on the morning of the 21st. On the same morning at Castle Rock the temperature dipped to 26 degrees below zero. During the period…other daily temperature records were set at Denver…including: record low maximum of 3 degrees below zero on the 20th and a record low of 17 degrees below zero on the 23rd. The record low was equaled with 16 degrees below zero on the 20th and 21 degrees below zero on the 21st. Snowfall totaled 2.7 inches at Stapleton International Airport from the 19th through the 21st.

20

In 1894…southwest winds were sustained to 40 mph with gusts to 48 mph. The Chinook winds warmed the temperature to a maximum of 69 degrees…which was a record high temperature for the date. The minimum temperature dipped to only 33 degrees.

In 1903…northwest Chinook winds sustained to 54 mph with gusts to 60 mph warmed the temperature to a high of 58 degrees.

In 1948…strong winds occurred along the eastern foothills from Boulder north. Wind gusts to 45 mph were recorded at Valmont with a gust to 30 mph at Boulder airport. Some damage occurred. Wind gusts to 50 mph caused some blowing dust at Stapleton Airport.

In 1957…strong Chinook winds…gusting to 51 mph from the northwest…warmed the afternoon temperature to a high of 54 degrees.

In 1981 high winds were reported in the foothills with a peak gust of 87 mph recorded at Wondervu.

In 1992…strong Chinook winds raked the eastern foothills with 69 mph recorded at Table Mesa in south Boulder. Southwest winds gusted to only 21 mph at Stapleton International Airport.

In 1996…five construction workers were injured…two seriously…when a sudden wind gust blew over a 30-foot- high retaining wall they were working on in western Lakewood. The scaffolding they were standing on collapsed…and some were pinned under the rubble for 15 minutes. Wind gusts of 60 to 75 mph were reported in the area. Southwest winds gusted to only 24 mph at Denver International Airport.

In 2004…strong downslope winds developed over the eastern mountain slopes and spread over metro Denver. Peak wind gusts approached 100 mph along the foothills of Boulder County. In Superior…a 1200-square-foot section of roof was peeled off the gymnasium at Monarch High School. Two semi-trailers were toppled on Colorado highway 58 at McIntyre Street and another at c-470 and west Bowles Avenue. Two airplanes were damaged by wind-blown debris at Jefferson County Airport. The high winds forced the closure of State Highway 93 between Golden and Boulder for approximately two hours. Insurance agents estimated 650 to 850 homes suffered wind damage in the Boulder and Louisville areas. In addition…downed trees and power lines left about 1000 residents…mainly in the Boulder area…without electricity. At least three people suffered minor injuries in the storm. Peak wind reports included: 95 mph in Superior…92 mph at Jefferson County Airport…85 mph in Golden…81 mph in Boulder…80 mph in Broomfield and Evergreen…and 79 mph in Louisville. West northwest winds gusted to 59 mph at Denver International Airport.

20-21

In 1969…high winds caused widespread…but mostly minor damage to roofs…windows…and power lines and overturned some house trailers in areas along and just east of the foothills. Wind gusts of 60 to 70 mph were reported in Boulder and south of Boulder at Rocky Flats. A wind gust to 115 mph was measured in Boulder at the National Center for Atmospheric Research. At Stapleton International Airport…west winds gusted to 44 mph on the 20th and to 45 mph on the 21st. The warm Chinook winds warmed the high temperature to 56 degrees on the 20th and to 65 degrees on the 21st.

In 2006…a major blizzard buried greater metro Denver and the adjacent foothills in deep snow. A slow moving upper level low pressure center produced deep moist upslope flow over the high plains and against the eastern slopes of the mountains…allowing heavy snowfall to persist for 34 hours across metro Denver. Total snow accumulations ranged from 1 to 2 1/2 feet across the city and from 2 to nearly 4 feet in the foothills. Adding to the misery… Strong north winds sustained at 20 to 35 mph with gusts from 45 to nearly 60 mph produced much blowing snow and piled the snow into drifts from 6 to 12 feet high…closing businesses and bringing all transportation to a halt. The storm forced the closure of Denver International Airport for a total of 45 hours which snarled the nation’s air traffic system. This was the longest closure in the airport’s 12 year history. The closure stranded nearly 5000 travelers when 2000 flights were canceled. Many inbound flights were diverted to other airports…stranding even more passengers. Many of the stranded travelers failed to reach their final destinations until days after the airport re-opened due to fully booked flights during the holiday season. Police and national guardsmen rescued hundreds of commuters stuck in their cars…and sent them to temporary shelters set up by the Red Cross. All interstates and other major highways in and out of Denver were closed. Greyhound was forced to cancel all bus trips from Denver. Mail delivery was suspended. The Regional Transportation District suspended all metro Denver bus service for the first time since the March 2003 blizzard. The roof of a discount store in Aurora collapsed under the weight of the heavy snow. In Lakewood…a power outage left 5600 residents without electricity for a brief time. Metro Denver snowfall amounts included: 34 inches 10 miles southeast of Buckley AFB…32 inches in Littleton…30 inches in Thornton and near Castle Rock…29.5 inches near Parker…28 inches in Wheat Ridge…25.5 inches at centennial airport…25 inches at Niwot…24 inches in Aurora…22.5 inches at Greenwood Village… 22 inches in Arvada…21.5 inches in Lakewood…20 inches in Longmont…and 15.5 inches in Boulder. Snowfall measured 20.7 inches officially in the Denver Stapleton area. This ranked the snowfall as the 7th greatest in the city since 1946. North winds were sustained to 37 mph with gusts to 55 mph at Denver International Airport. In the foothills snowfall totaled: 42 inches at Conifer and 11 miles southwest of Boulder…40 inches at Evergreen…39 inches at Aspen Springs… 37.5 inches 8 miles north of Blackhawk…33 inches near Nederland…31 inches at Intercanyon and near Tiny Town…30.5 inches atop Buckhorn Mountain…30 inches near Indian Hills… 29 inches at Rollinsville…24 inches near Gross Reservoir and Ralston Reservoir…22.4 inches atop Crow Hill…and 20 inches near Georgetown. Snowpacked and rutted streets and parking lots persisted for a month or more after the storm and subsequent storms. The heavy snowfall created a snow removal controversy when many citizens complained that residential streets were not cleared in a timely manner in the city and in some suburban areas. This was in spite of the fact that tens of millions of dollars were spent on snow removal. In the city of Denver…snow cover of an inch or more from this storm and subsequent storms persisted for 61 consecutive days…through February 19…2007. This is the second longest period of snow cover on record in the city. Many homeowners who had extensive Christmas lights and decorations in their yards were not able to remove the lights because the wires were buried in deep snow and ice until the end of February or later.

20-22

In 1933…strong downslope winds produced a warm spell. Low temperatures of 43 degrees on both the 20th and 21st and 41 degrees on the 22nd were record high minimums for those dates. High temperature of 67 degrees on the 21st was a record maximum for the date. High temperatures of 56 degrees on the 20th and 69 degrees on the 22nd were not records; however…the 69 degrees was the warmest of the month. West to northwest winds were sustained to 20 and 24 mph on the 21st and 22nd respectively.

20-23

In 1918…light snowfall on each day totaled 12.0 inches over downtown Denver. Northeast winds were sustained to 16 mph on the 21st.

20-25

In 1983…an extremely bitter cold spell occurred. The temperature remained below zero for 115 hours in Denver… The longest sub-zero period on record. The mercury dipped to 21 degrees below zero on the 21st…the coldest recorded temperature in over 20 years. The cold was accompanied by winds that plunged chill factors to 50 to 70 degrees below zero. Two people froze to death in Denver; both were found outside dead of exposure. Numerous cases of frostbite were reported. Hundreds of water pipes broke from the intense cold…water mains and natural gas lines also fractured…and electricity consumption reached record levels. Light snow totaling 5.8 inches fell at times…and holiday traffic was delayed at Stapleton International Airport for several hours. Eight daily temperature records were set at the time. The all-time record low maximum temperature for the month of 8 degrees below zero on the 21st still stands today. Other temperature records still standing include record low maximum temperatures of 5 degrees below zero on both the 22nd and 23rd and 4 degrees below zero on the 24th.

21

In 1884…light snow fell from an apparent cloudless sky between 4:15 am and 5:00 am. Snowfall totaled 3.5 inches for the day.

In 1900…west winds sustained to 46 mph with gusts to 54 mph warmed the temperature to a high of 59 degrees.

In 1910…heavy snowfall totaled 8.0 inches in downtown Denver. Northwest winds were sustained to 25 mph.

In 1961…strong winds associated with a cold front whipped snow across metro Denver. West wind gusts to 62 mph were recorded at Stapleton Airport. There was considerable damage to power lines…signs…and Christmas decorations. In Denver…4 people were injured by wind-caused accidents. Two small planes were flipped over at Stapleton Airport while attempting to land. Only a trace of snow fell at Stapleton Airport.

In 1983…the high temperature climbed to only 8 degrees below zero at Stapleton International Airport. This set the record for the lowest maximum temperature of the month.

In 1987…strong winds howled in the foothills and in Boulder. Wind gusts reached 78 mph in east Boulder…85 mph at Table Mesa in southwest Boulder…93 mph near Rollinsville…and 97 mph at the National Center for Atmospheric Research in Boulder. West winds gusted to 37 mph at Stapleton International Airport.

21-22

In 1969…strong winds raked the eastern foothills in Boulder and Jefferson counties. Wind gusts to 115 mph were recorded at the National Center for Atmospheric Research in Boulder…while in downtown Boulder winds gusted to 75 mph. Some damage occurred.

In 1981…a snow storm dumped 3 to 8 inches of snow across eastern Colorado. Snowfall totaled 6.8 inches at Stapleton International Airport where north winds gusted to only 17 mph.

In 2011…large scale lift from an upper level low combined with a deep easterly upslope flow behind a cold front to produce heavy snow in and near the Front Range Foothills and Palmer Divide. Storm totals ranged from 1.5 to 3 feet in the Front Range Foothills…with 1 to 1.5 feet along the Urban Corridor. In the Front Range Foothills and Palmer Divide…storm totals included: 36.5 inches… 7 miles southwest of Boulder; 32 inches…12 miles northwest of Golden; 28 inches at Genesee; 24.5 inches…3 miles west of Jamestown; 23 inches at Bergen Park; 21 inches at Evergreen and Gross Reservoir; 19 inches near Eldorado Springs and 3 miles west-southwest of Conifer; 17 inches…4 miles south-southwest of Tiny Town; and 13.5 inches…15 miles north of Elizabeth. Along the Urban Corridor…storm totals included: 18 inches in Golden; 14.5 inches in Boulder…13 inches at the National Weather Service in Boulder; 12.5 inches…5 miles south-southwest of Arapahoe Park; 12 inches at Lone Tree; 11.5 inches in Broomfield; 11 inches in Arvada…4 miles northwest of Elbert…Niwot and Wheatridge; 10 inches in northwest Denver; with 7.3 inches at Denver International Airport.

21-23

In 1924…heavy snowfall totaled 7.9 inches over downtown Denver. During the storm north to northeast winds were sustained to 21 mph. Temperatures were quite cold…ranging from a high of 24 degrees on the 21st to a low of 5 degrees below zero on the 23rd.

In 1964…high winds were recorded along the eastern foothills. A wind gust to 100 mph was registered at Jefferson County Airport near Broomfield. In Boulder… Where many thousands of dollars in damage occurred…warm Chinook winds gusted in excess of 45 mph downtown. A wind gust to 82 mph was recorded at the National Center for Atmospheric Research in Boulder. Heavy damage to power lines…homes…and roads was reported at Evergreen…Golden… And Boulder. Several people were injured by wind-caused accidents. West winds gusted to 53 mph on the 22nd and to 51 mph on the 23rd at Stapleton International Airport where some blowing dust occurred. The Chinook winds warmed temperatures in Denver to highs of 68 degrees on the 22nd and 71 degrees on the 23rd.

22

In 1885…a windstorm produced sustained west winds to 48 mph. The winds were strong all afternoon and evening.

In 1892…terribly strong winds hit the foothills above Boulder. The wind was described as a young tornado…but likely was straight line in nature. Winds in Boulder remained calm.

In 1901…the passage of an apparent cold front produced north winds sustained to 48 mph with gusts as high as 60 mph.

In 1922…a major storm dumped 8.0 inches of snow in downtown Denver.

In 1941…post-frontal heavy snow fell over downtown Denver where 8.0 inches of new snow were measured. Northwest winds were sustained to 26 mph. The cold front and snowfall abruptly broke a week of warm weather with high temperatures in the 50’s and 60’s.

In 1977…high winds unroofed a mobile home in Broomfield. Wind gusts reached 93 mph at Table Mesa in south Boulder and 74 mph at Rocky Flats. West winds gusted to 52 mph at Stapleton International Airport.

In 1988…high winds hit many foothills areas. Recorded wind gusts reached 95 mph just north of Boulder and 80 mph on Table Mesa. The strong winds caused power outages around Boulder. West winds gusted to 45 mph at Stapleton International Airport.

In 1990…the all-time lowest recorded temperature in December… 25 degrees below zero…occurred. The same temperature was also reached on December 24…1876.

22-23

In 1926…snow was heavy and totaled 6.7 inches in downtown Denver. Northeast winds were sustained to 17 mph with gusts to 18 mph on the 23rd.

In 1979…heavy snow blanketed metro Denver. Total snowfall at Stapleton International Airport was 6.9 inches…and north winds gusted to 20 mph. Most of the snow…5.7 inches…fell on the 22nd.

In 1984…strong Chinook winds howled along the Front Range foothills. At Table Mesa in southwest Boulder…gusts reached 108 mph on the morning of the 23rd. Gusts to 79 mph were clocked in Golden Gate Canyon. Gusts to 94 mph were reported in east Boulder. The winds flattened a two floor cinder block building under construction in Boulder… Causing 75 thousand dollars damage. Flying debris from the building slightly injured a policeman. A chain link fence was blown down. Dozens of windows and roofs were damaged in Boulder…along with mobile homes and cars. Numerous trees and power lines were downed. A giant plastic bubble dome was blown apart and collapsed…causing at least 100 thousand dollars damage. West winds gusted to 41 mph at Stapleton International Airport on the 23rd.

23

In 1915…apparent Bora winds were sustained to 46 mph with gusts to 58 mph. Snowfall was only 0.8 inch in the city.

In 1955…west-northwest winds gusted to 55 mph at Stapleton Airport. The downslope winds kept the low temperature from dipping below 50 degrees…the record highest minimum for the month.

In 1969…a strong wind gust did 4 thousand dollars in damage just west of Broomfield. Minor injuries also occurred.

In 1977…high winds occurred in Boulder with 90 mph recorded at several locations. A wind gust to 72 mph was reported at Lafayette. West winds gusted to 39 mph at Stapleton International Airport.

In 1989…high winds were reported in the foothills west of Denver. At Rollinsville…a wind gust to 90 mph was measured. Northwest winds gusted to 44 mph at Stapleton International Airport.

In 2007…high winds developed in and near the Front Range foothills of Boulder and Jefferson counties. Peak gusts included: 89 mph at the national wind technology center; 88 mph atop Niwot Ridge; 83 mph…4 miles east- northeast of Bergen Park; 80 mph…3 miles southeast of Jamestown. At Denver International Airport…east of the surface trough…southeast winds gusted to 28 mph.

23-24

In 1907…winds nearly as strong as a hurricane raked Boulder and areas north of Denver…killing one person and injuring others. Property damage was minor.

In 1973…a pre-Christmas blizzard…the second in 5 days… Produced strong winds and dumped heavy snow across metro Denver. Nearly a foot…11.8 inches…of snow fell at Stapleton International Airport where north winds gusting from 30 to 40 mph produced much blowing snow. The strong winds whipped the snow into 2- to 4-foot drifts…closing many roads and airports. About 10 thousand people were stranded at Stapleton International Airport for up to 24 hours.

In 1978…wind gusts to 90 mph on the 23rd and 73 mph on the 24th were recorded in Boulder. A townhouse under construction was severely damaged by the winds. At Stapleton International Airport…west winds gusted to 37 mph on the 23rd and northwest winds gusted to 35 mph on the 24th.

In 1987…a snowstorm assured a white Christmas for metro Denver…where 4 to 8 inches fell. Amounts in the foothills ranged from 10 to 18 inches. Snowfall totaled 3.9 inches at Stapleton International Airport…where north winds gusted to 32 mph on the 23rd.

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Wednesday brings one more unseasonably warm day before the bottom falls out

Wednesday, December 20th, 2017 5:14am MDT

If you can, get out and enjoy the mild weather today because significant changes are afoot beyond that. Tomorrow will offer much colder temperatures and snow and, in fact, mercury readings are likely to be a good bit below normal through the weekend.

For today, we start out with a bit of cloud cover but that will ease up leading to mostly sunny skies for most of the day. Winds will be out of the southwest. Temperatures start out chilly then will warm to a high of around 61 degrees.

Tonight, after midnight, a trough and cold front moves in and that will signify the start of the downhill slide. Overnight lows tonight will be around 20 degrees with blustery winds out of the northeast. Some flurries will be possible after midnight with increasing chances for snow as we head toward dawn on Thursday.

Tomorrow will be the first day of wintry conditions we have seen in a while. Snow will be likely through the morning hours then ease in the afternoon. Total accumulations for Thornton look to be on the order of 1 to 3 inches or so. It will also be quite cold with highs tomorrow only in the mid-20s.

Below normal temperatures will stick with us through Christmas with another chance for snow coming Saturday.

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Tuesday brings another mild day with plenty of sun, calm conditions

Tuesday, December 19th, 2017 5:09am MDT

What will today’s weather hold for Thornton? Pretty much just copy yesterday’s and paste it into today as there will be little change.

We start out the day with sunny skies and those will continue through the day. Only a few clouds here and there will be seen. Winds will be light and out of the south, conditions calm. Temperatures will once again climb steadily in the morning, peaking close to the mid-50s.

Tonight, we’ll see a few more clouds with lows right around 30 degrees.

Tomorrow will be another mild day but then, as we have been mentioning, things will be turning much colder and snow enters the forecast. Details here.

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Thornton’s workweek weather starts out mild and calm, will end very cold

Monday, December 18th, 2017 5:03am MDT

It looks to be another very pleasant, unseasonably warm day for us. We will actually put together a few days like that before much colder weather arrives for the latter part of the week.

For today, sunny skies kick things off and we should continue to see a good bit of sun throughout the day. Winds will be light and out of the southwest initially, shifting to the southeast later. Temps start out cold and below freezing but then bounce back nicely and we should see highs in the mid-50s.

Looking ahead, Tuesday and Wednesday will offer similarly mild conditions to today. After that, a cold front is going to come through followed by subsequent reinforcements of cold air that will see things turn much, much colder Thursday through the weekend.

Enjoy the warmth for now but be prepared! More in the extended forecast.

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