Category Archives: Climatology

Climatology, Colorado Weather, Thornton Weather

July 5 to July 11 – This week in Denver weather history

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July 5 - July 11 - This week in Denver weather history.
July 5 - July 11 - This week in Denver weather history.

Our look back at this week in Denver weather history reminds us that severe weather can continue to strike, even during what is normally a relatively calm month.  Lightning, hail and flooding are three continuous threats as we see during our look back at history this week.

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. This was one day short of equaling the all time record.  The record of 18 consecutive 90 degree or above days was first set from July 1st through July 18th…1874.  The record was equaled from July 6th through July 23rd…1901.

4-5  

In 1875…nearly every railroad running into the city was damaged by heavy thunderstorm rains.  The heavy rains washed out wooden bridges over normally dry creeks. Some trains were entirely suspended.  In the city…heavy thunderstorm rain totaled 1.05 inches on the 4th…but only 0.28 inch on the 5th.

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.

5    

In 1908…a late evening thunderstorm produced sustained north winds to 40 mph…hail…and 0.45 inch of precipitation.
 
In 1949…a dust devil…possibly a small tornado…was observed 3 miles to the northwest of Stapleton Airport.
 
In 1973…the temperature reached 100 degrees at Stapleton International Airport.
 
In 1974…strong thunderstorm winds damaged a mobile home…a barn…two houses…and several sheds near Watkins.
 
In 1975…a thunderstorm wind gust to 53 mph was recorded at Stapleton International Airport.  Hail up to 3/4 inch in diameter fell over the northwest suburbs and in northwest Denver.
 
In 1977 three houses in Denver were struck by lightning. Some heavy damage and fire occurred.
 
In 1990…lightning caused minor damage to houses in Castle Rock…Louviers…and Littleton.
 
In 1996…lightning caused only minor damage when it struck a home in Evergreen.  Lightning from a fast moving thunderstorm blasted a large hole in the side of a house in Lakewood.  Lightning triggered a minor power outage in the Boulder area.  About 200 homes were affected.
 
In 2001…severe thunderstorm winds gusted to 60 mph at Denver International Airport and to 70 mph…7 miles southwest of the airport.
 
In 2008…microburst winds downed a large tree and some power lines near a Denver apartment complex.  Several of the tenants’ vehicles were damaged.

Continue reading July 5 to July 11 – This week in Denver weather history →

Climatology, Thornton Weather

A Preview of Thornton’s July Weather – A Stormy Month

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Change is of course the one constant in Denver’s weather but come July, things actually get pretty consistent. The standard formula for a day in July is a sunning morning, clouds developing in the late morning and early afternoon. Come mid-afternoon, thunderstorms are rolling off of the foothills and into the metro area and the eastern plains. These storms do occasionally reach severe status containing hail, gusty winds and heavy downpours of rain.

In fact, the worst hail storm on record in Denver history hit western sections of the city on July 11th, 1990. Baseball and softball sized hail from this ferocious storm caused millions of dollars worth of property damage.

July is the most stormy month of the year in fact with thunderstorms occurring on average 11 days per month – or once every three days. These slow moving storms are one of the reasons July is Denver’s second rainiest month with an average of 2.16 inches of rain (second only to May). However, these storms are also often very localized and cause widely varying precipitation amounts across the metro area. It is not unusual for one area of down to be deluged while others remain entirely dry. With these severe storms, flash flooding remains a possibility.

View the complete July 2009 preview along with a look back at July 2008 here.

Climatology, Colorado Weather, Thornton Weather

June 28 to July 4 – This week in Denver weather history

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June 28 to July 4 - This week in Denver weather history
June 28 to July 4 - This week in Denver weather history

As always, an interesting week in Denver and Thornton weather history.  Various severe weather items are noteworthy, none more so than on July 2, 2006 when a teenager wearing an iPod was struck with lightning.  The music player actually contributed to the teen’s injuries by providing a direct route for the electricity into the victim’s head via the headphones.

From the National Weather Service:

21-3 

In 2002…the maximum temperature in Denver equaled or exceeded 90 degrees for 13 consecutive days…equaling the 5th longest such streak on record.  The record of 18 consecutive days was set during the summer of 1901.

28   

In 1873…there was a great deal of smoke over the city from forest fires in the mountains.
 
In 1875…smoke from forest fires in the foothills south of Denver were visible from the city.
 
In 1913…an apparent dry microburst produced southwest winds sustained to 44 mph with gusts to 48 mph in the city.
 
In 1925…a thunderstorm produced north winds sustained to 38 mph with gusts to 44 mph.
 
In 1958…a microburst caused a brief wind gust to 58 mph at Stapleton Airport.
 
In 1964…lightning struck several homes in metro Denver… Sparking fires.  Some flooding occurred in the stockyards area…at West 45th Avenue and St. Paul Street…and along Harvard Gulch.
 
In 1997…strong microburst winds of unknown speed downed several trees…signs…and at least one light pole in the Fort Lupton area.  Two trees knocked over by the storm downed power lines causing scattered outages.
 
In 2002…a thunderstorm wind gust to 60 mph was recorded in Parker.
 
In 2005…severe thunderstorms produced wind gusts to 66 mph near Longmont and to 60 mph near Niwot.  No damage was reported.  A thunderstorm produced a wind gust to 55 mph at Denver International Airport during the afternoon.

29   

In 1874…eight different fires in mountain forests were visible from the city.  All of the fires were extensive… And the volume of smoke from each was immense.  Three of these fires had been burning from the 18th with varied intensity.
 
Continue reading June 28 to July 4 – This week in Denver weather history →

Climatology, Thornton Weather

June 2009 is now the 2nd wettest Denver June

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From the National Weather Service: June 2009 has moved into the second wettest June since Denver weather records began in 1872.  So far for June 2009, through June 26th, the Denver International Airport (DIA) has measured 4.86 inches of liquid (and there are still 4 more days left in June).  The 4.86 inches of water is 3.52 inches above normal through the 26th.  Last year, June 2008 had only measured 0.73 inch again through the same June time frame.

The wettest June on record for Denver was in June 1882 when 4.96 inches of moisture was collected in the rain bucket.

For the 2009 year so far, 10.38 inches of water has been measured at DIA which is a very impressive 2.51 inches above the normal through June 26th.   Last year in June, only 3.04 inches had been recorded through the same time frame.

Note:  The average Denver annual precipitation is 15.81 inches.

As always, we have to ask, do Denver weather and climate records have an asterisk attached?  Read our Examiner.com investigation to see why maybe they should.

Climatology, Thornton Weather

A Preview of Thornton’s June Weather – The Severe Weather Month

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Denver is historically Thornton's true severe weather month.
Denver is historically Thornton's true severe weather month.

June is historically Denver’s severe weather month and severe thunderstorms, tornadoes and hail are notorious visitors to Denver and across eastern Colorado during the month.  In fact, over 40 percent of the tornadoes that occur in Colorado are observed in June and these are typically the most destructive of the year.  Severe thunderstorms have also caused major property damage across the Front Range during the month.

In just the last 25 years or so, there have been some particularly notable storms in June.  Tornadoes have struck the metro area including one that longtime Thornton residents will recall on June 3, 1981.  53 residents were injured, 25 homes were destroyed and 239 other structures were damaged.  Others tornadoes in the metro area include southeast Denver and Aurora on June 8, 1986 and east Denver on June 13, 1984.  Severe thunderstorms occurring on June 13, 1984 dumped large hail making it one of the worst and the second costliest storm in Denver history.  More recently, on June 20, 2001, a major hail storm moved across Denver International Airport dropping hailstones as big as two inches in diameter. Damage was extensive on and near the airport.

For complete details on what we can expect in June, click here to view our June weather preview.

Climatology, Thornton Weather

Denver officially breaks high temperature record for this date

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Denver set a temperature record for today, May 19.
Denver set a temperature record for today, May 19.

It’s official.  At 1:24pm today the temperature at Denver International Airport reached 90 degrees setting a new record high temperature for May 19.  This breaks the previous record high for this date of 89 degrees set in 2006. 

Wtih some cloud cover moving in and a chance for thunderstorms in the forecast, it appears that is as high as the mercury will climb today. 

But is it truly a record?

One does have to wonder though, is it truly fair to call this a record?  When the National Weather Service moved Denver’s official monitoring station from Stapleton to Denver International Airport, some say the city’s climate records were forever altered.  For more information and analysis of the controversy, check out this story:  Do Denver weather and climate records have an asterisk attached?

Climatology, Thornton Weather

A Preview of Denver’s April Weather – Something for Everyone

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Do April showers bring May flowers? Find out in our April 2009 weather preview!
Do April showers bring May flowers? Find out in our April 2009 weather preview!

April marks a transition between winter and summer for most of the country but for Denver it is especially true as we can see a stunning variety of weather. The proverbial April showers are certainly a possibility for Denver. Snow? Tornadoes? Thunderstorms? You bet – all can happen! For good measure throw in a chance for hail and even dust storms and April gives every type of weather condition you could like – or hate.

The good news is that sunshine and warmer temperatures are usually in abundance as the normal highs during the month move up from 57 degrees on the first to 65 degrees on the 30th. It is not unusual to have a number of days well into the 70’s and the low 80’s. We also see the normal lows move above freezing from 30 degrees at the start of the month to 39 degrees by the end. Temperature extremes can hit both ends of the spectrum with a record low of 2 degrees below zero on April 2, 1975 and a record high of 90 degrees on April 30, 1992.

Get all the details here in our complete April 2009 preview.

Climatology

Have a headache? Blame the weather!

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Have a headache? The weather may be the cause!
Have a headache? The weather may be the cause!

We have oftentimes heard headache sufferers, particularly those that get migraines, attribute their pain to the weather.  These had sometimes been dismissed as an old wives tale but a new study shows that there is a great deal of truth to this. 

The Beth Israel Deaconess Medical Center (BIDMC) in Boston has recently completed the first large-scale study showing how environmental conditions like weather and air pollution can influence headache pain.  Over 7,000 patients were studied in order to see if there is a link.

Kenneth Mukamal, MD, MPH, one of the authors of the study and a physician at BIDMC explains that, “Air temperature, humidity and barometric pressure are among the most frequent reasons that people give for their headache pain.  But none of these reasons have been consistently verified. We wanted to find out if we could verify this ‘clinical folklore’.”

Mukamal and his coauthors compared levels of pollutants and meterological variables at the time of the patient’s hospital visit with corresponding levels on preceding days and subsequent weeks.  Using meteorlogical and pollutant monitors they compared measurements of factors such as air temperature, barometric pressure, humidity, and dioxides from the three days prior to a patients’ visit to see if there was a correlation between these items and the patients’ headaches. 

The results of the study seem to prove that this old wives tale is true.  Of the factors considered, higher air temperature in the 24 hours just prior to a patient’s visit to the hospital was most associated with the headache symptoms.  There was a 7.5 percent higher risk of severe headaches for each increase of nine degrees in temperature.  Although not as profound, lower barometric pressure in the 48 to 72 hour period before a hospital visit also was seen to trigger headaches. 

Dr. Mukamal says, “Certainly our results are consistent with the idea that severe headaches can be triggered by external factors.  These findings help tell us that the environment around us does affect our health and, in terms of headaches, may be impacting many, many people on a daily basis.”

The next time you have a headache, if it was a good bit warmer the day before or the barometric pressure was lower a couple days before, you may have found the cause of your headache! 

Climatology, Colorado Weather, Thornton Weather

Do Denver weather and climate records have an asterisk attached?

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The old Stapleton International Airport site and Denver International Airport are separated by 12 miles. Is it accurate tto compare weather between the two locations?
The old Stapleton International Airport site and Denver International Airport are separated by 12 miles. Is it accurate to compare weather between the two locations?

February 2009 is Denver’s least snowiest February on record.  A new record high temperature is recorded on January 21, 2009.  Record low temperatures are recorded on December 14th and 15th of last year. 

These announcements are common and we all take notice when we hear them and they make for great water cooler chat topics but are these claims accurate? 

In 1995 Denver finally opened its new airport, Denver International Airport, out on the plains east of the city.  This new facility, 12 miles as the crow flies northeast of the old Stapleton International Airport, moved the airport from an urban environment to a rural one and more than 19 miles from the center of Denver.  Following that move, the National Weather Service (NWS) began taking some of its official measurements at the glistening new airport.  In doing so, some say Denver’s climate records have forever been altered and as such any weather record should have an asterisk attached to it. 

On Examiner.com we have launched a three part investigative series on this topic.  It is a fascinating read – click here to read the rest of the story.

For all the details, read the rest of this story on our Denver Weather Examiner page. Examiner.com - Get inside Denver weather
Climatology, Colorado Weather, Thornton Weather

Denver and Thornton’s March 2009 climatological preview

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Denver and Thornton's March 2009 climatological preview
Denver and Thornton's March 2009 climatological preview

March in Denver typically means frequent and rapid weather changes. The days grow longer and we start enjoying more sunshine and sometimes summer-like weather. However, on occasion arctic air masses can still force their way south into Colorado dropping temperatures quickly and markedly.

These changes are due to Marches “in between” status – elements during the month have much in common with winter and spring. In addition to arctic fronts, Pacific storms frequently move across Colorado from the west and warm moist air streams up from the Gulf of Mexico northeastward into the state. When these cold fronts collide with the warmer air masses the result can be some crazy weather.

Get all the details in our March 2009 climatological preview here.