Sweltering, unseasonably warm temperatures gripped much of the contiguous United States last month breaking many records. In the final analysis of the month, NOAA announced that July was the hottest month ever recorded in the U.S. How hot was it? Read the rest of this story on Examiner.com
For the second month in a row, Thornton saw extraordinarily warm temperatures in July. The month not only was the warmest July ever recorded by ThorntonWeather.com, it was the warmest month recorded since we began operation.
The average temperature for July 2012 was an astonishing 75.5 degrees. This was 1.8 degrees above Thornton’s average for July over the past six years, a significant increase.
Temperatures ranged from a high of 98.7 degrees on July 1 down to a low of 56.6 degrees on July 11.
In all we recorded 23 days with high temperatures at or above 90 degrees. We did however manage to escape the month without breaking the century mark.
In terms of precipitation Thornton didn’t fare too poorly. We recorded 1.92 inches of precipitation in our rain bucket. This was only 0.03” below the six year average of 1.95 inches.
For comparison, Denver saw an official average monthly temperature of 78.9 degrees as measured at Denver International Airport. Further, they only recorded 0.48 inch of precipitation. For more details on Denver’s July 2012 weather, please visit this story on Examiner.com.
More on ThorntonWeather.com:
July 2012 Graphs
The effects of our annual monsoon season are portrayed in detail in our look back at this week in Denver weather history. Numerous cases of flooding resulting from heavy rainfall are seen as are other severe weather events including hail and even tornadoes.
From the National Weather Service:
13-5
In 2008…a streak of 24 consecutive days of 90 degrees shattered the previous record of 18 consecutive days established in 1901 and 1874. Ironically…no new single day record high temperatures were set in the month of July. In August however…a record of 104 degrees was set on the 1st…and another record of 103 degrees was set on the 2nd. In addition…a record low min of 70 degrees was set on August 2nd.
18-2
In 1987…a streak of 16 consecutive days of 90 degrees ranked 4th on the list of hot streaks. The record of 24 consecutive days was established in the summer of 2008.
27-31 in 1956…96 percent of the total precipitation for the month of July occurred over the last five days of the month. Heavy thunderstorms produced 4.00 inches of rainfall at Stapleton Airport. This amount of precipitation in 5 days or less had been exceeded only 3 times in previous record. The last time had been in December of 1913 as snow. Considerable property damage occurred across metro Denver from flooding.
28-30
In 1889…dense smoke from forest fires in the mountains obscured the sun over the city for three days.
In 1971…a vigorous cold front late on the 28th produced northeast wind gusts to 39 mph and record breaking cold temperatures on the 29th and 30th. The temperature dipped to 47 degrees on the 29th and 43 degrees on the 30th… Setting record minimums for the dates. Upslope cloudiness along with rain and fog early on the 29th helped set a record low maximum temperature of 58 degrees for the date.
29
In 1878…a total eclipse of the sun was observed at 2:20 pm. From before to during the eclipse…the temperature in the sun fell from 114 degrees to 82 degrees…while the shade temperature fell from 89 degrees to 83 degrees.
In 1880…heavy thunderstorm rain and hail flooded streets and ditches.
In 25 minutes…0.76 inch of rain fell on the city along with large hail to 3/4 inch in diameter. There were no strong winds with the storm.
In 1890…a thunderstorm produced sustained west winds to 48 mph with gusts to 60 mph…but only 0.01 inch of rain.
In 1956…heavy rain and hail fell over west and north Denver.
In 1964…hail to 3/4 inch in diameter fell at Lowry Airfield.
In 1978…a small tornado was sighted just east of Parker. No damage was reported.
In 1989…heavy rain drenched all areas of the Front Range… Both in the foothills and adjacent plains. Amounts of 1 to 3 inches were general over the area. Damage was confined to a few minor road washouts and some street…basement…and crop flooding. Thunderstorm rainfall totaled 1.44 inches at Stapleton International Airport where north winds gusted to 43 mph. Lightning struck a 250 thousand dollar home near Nederland and started a fire which destroyed all of it except two garages. Lightning started a fire in a home in Evergreen. It reached the house by hitting a tree…then traveling through a metal clothesline strung between the tree and the building.
In 1995…thunderstorm winds gusted to 59 mph in Brighton. Thunderstorm winds from the south-southeast gusted to 41 mph at Denver International Airport. High temperature of 99 degrees was a new record maximum for the date in Denver.
In 1997…heavy rain caused flooding in an apartment building in Westminster. Several residents had to be evacuated from their apartments. A woman in aspen park received minor injuries…when lightning passed through an office window and struck her. She suffered temporary blindness for about 15 minutes.
In 2003…hail as large as 1 inch in diameter pelted Conifer… Highlands Ranch…and Franktown.
Continue reading July 29 to August 4 – This Week in Denver Weather History
Denver’s weather is rarely boring and our look back at this week in Denver weather history shows that. There have certainly been many notable thunderstorms with hail and damaging wind. However the most interesting item is the first – and only – recorded instance of snow during the month of July in the Mile High City.
7-25
In 1934…a streak of 15 consecutive days of 90 degrees ranked 5th on the list of hot streaks. The record of 24 consecutive days was established in the summer of 2008.
13-5
In 2008…a streak of 24 consecutive days of 90 degrees shattered the previous record of 18 consecutive days established in 1901 and 1874. Ironically…no new single day record high temperatures were set in the month of July. In August however…a record of 104 degrees was set on the 1st…and another record of 103 degrees was set on the 2nd. In addition…a record low min of 70 degrees was set on August 2nd.
14-15
In 1985…thunderstorms dumped heavy rain and hail at numerous locations along the Front Range from Denver north. Some of the heaviest rain fell in northern and western suburbs of Denver. Up to 2.6 inches of rain drenched Arvada…and Thornton was soaked with 2 inches in 45 minutes. At least 5 homes in Arvada suffered extensive damage from water and mud…and many streets and basements were flooded. In southern Jefferson County…11 homes were struck by lightning.
15
In 1879…a terrific hail storm occurred in the vicinity of Buffalo Station on the south park railroad in the South Platte River canyon about 39 miles south of Denver. Stones as large as hen’s eggs fell thick and fast and broke nearly every pane of glass in the windows of the building. A “waterspout” or cloudburst caused much loss of property from flash flooding on a nearby gulch. The torrent of water caused a deafening roar as it uprooted trees and carried huge Boulders and other debris. It struck the house and sawmill simultaneously and carried them away like straws…leaving little behind. The water continued to rush down the gulch for several hours. Serious damage was done to the south park railroad. The track and roadbed were destroyed for several miles. At about the same time…heavy rains in the vicinity of the headwaters of Cherry Creek produced a rapid rise in the creek…which drowned a few head of cattle and washed away two footbridges and some fences. Only 0.10 inch of rainfall was recorded in Denver.
In 1896…a thunderstorm produced sustained southwest winds to 40 mph with gusts to 46 mph.
In 1902…the temperature reached a high of 100 degrees in downtown Denver…which was a record maximum for the date.
In 1929…a thunderstorm did considerable damage to property in the eastern portion of the city. Heavy hail ranging in size from 1/4 to 3/4 inch in diameter…severe lightning… And high winds accompanied the heavy rain. Basements were flooded…and streets were impassable in places for several hours due to the heavy rainfall. Lightning damaged several telephone poles. Hail did extensive damage to gardens and flowers. The hail was up to a foot deep in places. There was no estimate of damage from the storm. A thunderstorm produced only a trace of rain and east winds to 24 mph in downtown Denver.
In 1959…thunderstorm rain totaled 0.41 inch in 8 minutes and winds gusted to an estimated 50 mph near downtown Aurora where half inch diameter hail was also reported. After the storm moved to the east…complete double rainbows were observed from the weather bureau office at Stapleton Airport.
In 1962…hail pelted the area in Adams County around Henderson and Brighton…causing extensive damage to corn…grain…beets…and row crops. Crop damage was estimated at 250 thousand dollars.
In 1963…a man received severe burns when struck by lightning while painting a building in south Denver.
In 1965…a state patrolman sighted a tornado near Bennett. It touched down over open ground…but caused no damage.
In 1967…heavy rains flooded streets and underpasses in south Denver. Heavy rain and minor wind damage were reported in wheat ridge…Aurora…Englewood…and Littleton. Basements were flooded and power disrupted. The clouds and rain resulted in a high temperature of only 72 degrees…which was a record low maximum for the date.
In 1974…a severe lightning storm damaged several homes and caused a number of power outages in both Denver and western Arapahoe counties.
In 1975…lightning killed a girl west of Boulder.
In 1982…winds gusted to 60 mph at Stapleton International Airport…and strong winds blew down walls at a construction site in Aurora where a nearby tree was uprooted.
In 1985…0.79 inch of rain fell in 30 minutes at Castle Rock. Much of the town lost power when lightning struck the town’s transformer.
In 1992…a man was struck by lightning while horseback riding near Castle Rock. Two people were struck by lightning near Highlands Ranch in south metro Denver. A man was struck by lightning while riding in the back of a pick-up truck in Franktown. All received minor injuries. Strong thunderstorms moved through east metro Denver…producing large hail and flash flooding. Hail up to 1 1/4 inches in diameter fell near Buckley Air National Guard base. Rainfall of 1 to 3 inches fell in Aurora in less than an hour…leaving water up to 18 inches deep in some areas. Thunderstorm rainfall was measured at 0.97 inch at Stapleton International Airport…where 3/8th inch diameter hail fell and south winds gusted to 44 mph.
Continue reading July 15 to July 21 – This Week in Denver Weather History
In looking back at this week in Denver weather history, one cannot be struck by the hail storms listed, if not for sheer number then by the damage they caused. The biggest of these storms occurred in 1990 and stands in the books as the most damaging hailstorm in United States history.
From the National Weather Service:
29-15
In 2000…the 29th marked the beginning of a near record hot streak for metro Denver. The high temperatures…as recorded at Denver International Airport…exceeded the 90 degree mark for 17 consecutive days from June 29th through July 15th. The record of 24 consecutive 90 degree or above days was set from July 13th through August 5th…2008.
29-15
In 2000…the 29th marked the beginning of a near record hot streak for metro Denver. The high temperatures…as recorded at Denver International Airport…exceeded the 90 degree mark for 17 consecutive days from June 29th through July 15th. The record of 24 consecutive 90 degree or above days was set from July 13th through August 5th…2008.
1-18
In 1874…a streak of 18 consecutive days of 90 degrees tied for second with another streak that was later set in the summer of 1901. The record of 24 consecutive days was established in the summer of 2008.
4-8
In 1989…one of the most intense heat waves on record roasted metro Denver. The temperature reached 100 degrees or more on 5 consecutive days. The city had previously never recorded more than 2 straight 100-degree days since records began in 1872. Water and electricity usage reached all time highs. The heat wave created extremely dry weather conditions…which contributed to a major forest fire in Boulder canyon on July 9th. The temperature reached 103 degrees on the 8th…and the mercury climbed to 101 degrees on both the 4th and 5th…and to 102 degrees on both the 6th and 7th. The low temperature of 68 degrees on the 8th equaled the record high minimum for the date.
6-23
In 1901…a streak of 18 consecutive days of 90 degrees tied for second with another streak set in the summer of 1874. The record of 24 consecutive days was established in the summer of 2008.
7-25
In 1934…a streak of 15 consecutive days of 90 degrees ranked 5th on the list of hot streaks. The record of 24 consecutive days was established in the summer of 2008.
8
In 1905…a thunderstorm produced 0.82 inch of rainfall and northeast winds sustained to 48 mph.
In 1977…strong winds turned over 2 light aircraft at Arapahoe County Airport…now centennial airport.
In 1987…a weak tornado was observed near Bennett.
In 1988…three separate tornadoes were sighted near Bennett. No damage was reported. One inch diameter hail was also reported.
In 1991…lightning started three house fires in Castle Rock. Damage totaled 13 thousand dollars. No injuries were reported.
In 1993…a dry thunderstorm microburst wind gust to 55 mph briefly reduced the surface visibility to 3 miles at Stapleton International Airport.
In 1997…one construction worker was killed and two others injured when a strong thunderstorm wind gust caused the scaffolding they were standing on to collapse near Parker. A dry microburst produced a wind gust to 54 mph at Denver International Airport.
In 1998…heavy thunderstorm rain forced the closure of Hampden Avenue between I-25 and Havana Street in southeast Denver. The high water made 2 or 3 lanes of the street impassable.
In 2001…severe thunderstorms produced large hail…damaging winds…and heavy rain across south metro Denver. Two people received minor injuries when a severe thunderstorm wind gust to 58 mph blew over several tents at the Cherry Creek Arts Festival. The same storm caused the roof of a hardware store in Tamarac Square to collapse. One employee received minor injuries when she was struck in the head by falling debris. The combination of intense rain and wind downed trees and power lines. Electrical power outages affected 35 thousand homes and businesses. At least 50 trees in city parks across south Denver were damaged. Up to 4.50 inches of thunderstorm rain fell across portions of southeast metro Denver. The underpass at I-25 and Parker road was inundated with 5 feet of water. Several other streets and underpasses in Aurora were also closed due to high water. Heavy rain caused extensive damage to several exhibits at the Cherry Creek Arts Festival. Flash flooding occurred when heavy thunderstorm rainfall caused toll gate creek to jump its banks. Several underpasses across south Denver had to be closed due to high water. A man received minor injuries when lightning struck a nearby tree at the Wellshire Golf Course. Hail as large as 1 1/4 inches in diameter fell in Englewood with 1 inch hail in the city of Denver…and 3/4 inch hail in Littleton. Thunderstorm winds gusted to 63 mph at Denver International Airport and to 62 mph in Englewood.
In 2005…a tornado touched down briefly near Brighton…but caused no damage.
In 2011…severe thunderstorms produced hail…up to 1 inch in diameter…and wind gusts to 60 mph across parts of Adams…Broomfield and Denver counties. At Denver International Airport…a peak wind gust to 59 mph from the west.
Continue reading July 8 to July 14 – This Week in Denver Weather History
As Colorado seems intent on starting a potentially record-setting streak of hot days, we see similar streaks in our look back at this week in Denver weather history. Also notable are the number of lightning and hail events that have injured, killed and caused extensive damage.
From the National Weather Service
29-2
In 1990…almost a year to date after the record breaking heat in early July 1989…the third longest heat wave in Denver history started. From June 29th through July 2nd the temperature reached 100 degrees or more on four consecutive days. The highest reading of 102 degrees occurred on the 29th…30th…and 1st. Combined with the 102 degree reading on June 27th this would have been the longest heat wave on record…but the temperature climbed to only 98 degrees on June 28th.
29-15
In 2000…the 29th marked the beginning of a near record hot streak for metro Denver. The high temperatures…as recorded at Denver International Airport…exceeded the 90 degree mark for 17 consecutive days from June 29th through July 15th. The record of 24 consecutive 90 degree or above days was set from July 13th through August 5th…2008.
30-1
In 1873…heavy rainfall overnight totaled 1.42 inches. Mountain peaks to the southwest of the city were covered with fresh snow on the morning of the 1st.
1
In 1915…northeast winds sustained to 41 mph with gusts to 50 mph occurred just before a thundershower in the evening. Rainfall was only 0.07 inch.
In 1941…unusually heavy thunderstorm rains flooded basements and blocked traffic. Water was curb high on many downtown streets. The thunderstorm also pelted the city with hail of unknown size. Rainfall in downtown Denver totaled 0.72 inch…but greater amounts likely occurred in other parts of the city.
In 1960…a severe dust devil moving through an Adams County suburban area blew over a fireworks stand…injuring an 11- year-old boy customer and two women operators of the stand. The boy was found under the demolished stand 100 feet away.
In 1961…hail as large as 1 1/4 inches in diameter was reported over east Denver.
In 1967…golf ball size hail fell over portions of metro Denver. Hail stones to 2 inches in diameter damaged roofs and broke windows in northeast Boulder. Marble to golf ball size hail fell at the Boulder airport. A funnel cloud was sighted over the foothills near Boulder. Hail stones of 1 to 2 inches in diameter were measured at Jefferson County Airport near Broomfield. Marble size hail fell in the vicinity of Arvada and Westminster.
In 1982…severe thunderstorms dropped large hail in Denver… Boulder…Commerce City…Lakewood…Wheat Ridge…Golden…and Arvada. Most locations reported hail size from 3/4 to 1 1/4 inches in diameter.
In 1990…the high temperature reached 102 degrees at Stapleton International Airport.
In 1998…hail to 1 1/2 inches in diameter fell near Bennett.
In 2001…the temperature climbed to a high of 101 degrees at Denver International Airport.
1-18
In 1874…a streak of 18 consecutive days of 90 degrees tied for second with another streak that was later set in the summer of 1901. The record of 24 consecutive days was established in the summer of 2008.
Continue reading July 1 to July 7 – This Week in Denver Weather History
It is readily apparent that July has thus far been a wet month given that we have seen eight straight days of thunderstorms. Yesterday the storms set a record for precipitation and Denver is on pace to make the month one of the wettest Julys on record.
Out at Denver International Airport yesterday, 1.03” of precipitation was recorded. This set the record for the date easily besting the old record of 0.45” set in 1993.
Here in Thornton we recorded 0.45” yesterday so a good bit less than out at the airport but still a decent shot of precipitation.
This brings Denver’s official total to 3.19” for the month so far. Average for the entire month of July is 2.16” so we are far ahead of that.
Number 10 on the ‘top 10 wettest Julys’ occurred in 1985 with 3.71”. Given the fact that the forecast continues to contain daily thunderstorms for the foreseeable future, there is a good chance we will exceed that before the month is over.
Thornton is ahead of the game in comparison to DIA as we have recorded 4.52” so far this month.
For eight days in a row monsoonal flow fed thunderstorms have struck Thornton and Tuesday night brought arguably the best show yet. Heavy rain, hail, gusty winds and an extraordinary amount of lightning roused residents soon after nightfall.
Storms initially formed in the afternoon and were focused south of Denver in Elbert County. Near Kiowa, Elizabeth and Agate hail up to 1 3/4” in diameter was recorded. The slow-moving storms deposited as much as five inches of rain near Agate. Three twisters were reported in Elbert County but no damage was realized.
It appeared for a time that Thornton was going to escape the intense weather but once the sun went down the picture changed dramatically. Seemingly out of nowhere a storm cell popped up at around 9:20pm and moved across the north Denver metro area.
Heavy rain fell across a large part of the area from downtown northward to Thornton. 1.76 inches of rain was recorded north of downtown Denver at DenverWX.com as the storm passed through.
Street flooding was reported across the surrounding areas causing difficulty for motorists.
Here in Thornton we were pounded with heavy rain and a great deal of pea-sized hail. ThorntonWeather.com recorded its first inch of rain in only 14 minutes and the storm total for the overnight storm was 1.90 inches.
Strong winds also brought down trees and power lines knocking out power to nearly 10,000 Denver area residents including some in Thornton. Xcel Energy reports power has been restored to most areas this morning.
Denver International Airport recorded a thunderstorm wind gust of 66mph shortly before 10:00pm. A ground stop was issued and all flights were temporarily delayed while the storm moved through.
Forecasters had predicted a late and shorter than normal monsoon season due to La Niña’s lasting effect – that however has not proven to be true.
Monsoonal flow pulling in moisture from Mexico started earlier than normal this year. Tuesday marked the eighth straight day for thunderstorms in the Denver metro area and the current weather forecast has at least a chance for storms through the weekend.
To date Thornton has recorded 4.22 inches of precipitation during the month of July. This far exceeds the Denver historical average of 2.16 inches for July and with the month less than half over, chances are we could achieve ‘top 10 wettest’ status by the end of the month.
La Niña is winding down and normally we would expect a drier than normal monsoon. Mother Nature however has other plans as she not only brought the season to Thornton early, it came with a vengeance this week.
In a presentation that just came out at the first of the month, the National Weather Service discussed the coming monsoon. At that time forecasters predicted a drier and shorter than normal monsoon for the Colorado Front Range. Thus far it has been anything but.
This past week copious amounts of moisture have streamed into Colorado. Coupled with daytime heating leading to a good deal of atmospheric instability, thunderstorms have been a daily occurrence. Strong winds and heavy rain have occurred virtually daily.
Over the past five days Denver has recorded 1.78 inches of rain at the city’s official monitoring station at Denver International Airport. Closer to where population actually lives even greater amounts have been seen.
Here in Thornton we have recorded 1.98 inches of rain over the past five days. Other amounts over the same period recorded at nearby stations include 1.79 inches in Arvada, 3.18 inches at Reunion in Commerce City, and 3.06 inches in north Denver.
On Friday evening, a slow-moving thunderstorm dumped heavy rain on the southern parts of Thornton. Video footage from storm chaser Tony Laubach (below) shows the end result as streets in the area of I-25 and 84th Avenue were flooded.
Is there an end in sight? Not in the immediate future. For at least the next few days atmospheric moisture will continue to be in abundance and we will continue to see the same general pattern. By mid-week we may see some drying but we can’t entirely eliminate the threat of afternoon thunderstorms.
As always you can get the latest Thornton forecast here.
Our normally widely varied weather settles into a somewhat standard pattern during the month of July. The mercury climbs each day in what is our hottest month and thunderstorms become very common during the afternoon and evening hours.
The average monthly high temperature for July is 88 degrees and can oftentimes get much higher than that. In fact, the record high temperature for all but seven days during the month are at or above 100 degrees.
Afternoon thunderstorms occur on average every three days during July. These events can be extreme and are known to bring heavy rains and damaging wind and hail.
Find out more about what to expect this July in our complete July weather preview.