Tag Archives: July Weather

Thornton gets pounded by nighttime storms bringing hail, wind and flooding rains

Lightning strikes east of 120th Avenue and Fairfax during Tuesday night's storms.
Lightning strikes east of 120th Avenue and Fairfax during Tuesday night's storms. View more images in the slideshow below. (ThorntonWeather.com)

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.

Monsoon season arrives early, brings heavy rains to Thornton area

A common scene this past week - thunderstorms develop over the Denver area.  (Twitpic / CodyCrouch)
A common scene this past week - thunderstorms develop over the Denver area. Watch video of the recent street flooding in Thornton below. (Twitpic / CodyCrouch)

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.

A look at Thornton’s July weather – Our hottest and stormiest month

Thornton's July weather previewOur 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.

Global temperatures on the rise – Second warmest July, warmest year-to-date

From the National Oceanic & Atmospheric Administration: The combined global land and ocean surface temperature made this July the second warmest on record, behind 1998, and the warmest averaged January-July on record. The global average land surface temperature for July and January–July was warmest on record. The global ocean surface temperature for July was the fifth warmest, and for January–July 2010 was the second warmest on record, behind 1998.

The monthly analysis from NOAA’s National Climatic Data Center, which is based on records going back to 1880, is part of the suite of climate services NOAA provides government, business and community leaders so they can make informed decisions.

Global temperature anomolies, July 2010. (NOAA)
Global temperature anomolies, July 2010. (NOAA)

Global Temperature Highlights

  • The combined global land and ocean average surface temperature for July 2010 was the second warmest on record at 61.6°F (16.5°C), which is 1.19°F (0.66°C) above the 20th century average of 60.4°F (15.8°C). The averaged temperature for July 1998 was 61.7°F (16.5°C).
  • The July worldwide land surface temperature was 1.85°F (1.03°C) above the 20th century average of 57.8°F (14.3°C) — the warmest July on record. Warmer-than-average conditions dominated land areas of the globe. The most prominent warmth was in Europe, western Russia and eastern Asia. Cooler-than-average regions included central Russia, Alaska and southern South America.
    • According to the Finnish Meteorological Institute, Finland set a new all-time maximum temperature on July 29 when temperatures soared to 99.0°F (37.2°C), surpassing  the previous record set in July 1914 by 2.3°F (1.3°C).
    • Western Russia was engulfed by a severe heat wave during much of July. On July 30, Moscow set a new all-time temperature record when temperatures reached 102°F (39°C), exceeding the previous record of 99.0°F (37.2°C) set four days earlier. Before 2010, the highest maximum temperature recorded in Moscow was 98.2°F (36.8°C), set nine decades ago.
    • According to the Beijing Climate Center, the July 2010 average temperature across China was 73.0°F (22.8°C), which is 2.5°F (1.4°C) above the 1971-2000 average and the warmest July since 1961.
  • The worldwide ocean surface temperature was 0.97°F (0.54°C) above the 20th century average of 61.5°F (16.4°C) and the fifth warmest July on record. The warmth was most pronounced in the Atlantic Ocean.
  • La Niña conditions developed during July 2010, as sea surface temperatures (SST) continued to drop across the central and eastern equatorial Pacific Ocean. According to NOAA’s Climate Prediction Center, La Niña is expected to strengthen and last through the Northern Hemisphere winter 2010-2011.
  • For the year-to-date, the global combined land and ocean surface temperature of 58.1°F (14.5°C) was the warmest January-July period on record. This value is 1.22°F (0.68°C) above the 20th century average.
Global temperature anomolies, January through July, 2010. (NOAA)
Global temperature anomolies, January through July, 2010. (NOAA)

Polar Sea Ice and Precipitation Highlights

  • Arctic sea ice covered an average of 3.2 million square miles (8.4 million square kilometers) during July. This is 16.9 percent below the 1979-2000 average extent and the second lowest July extent since records began in 1979. The record low July was set in 2007. This was the 14th consecutive July with below-average Arctic sea ice extent. July 1996 was the last year that had above-average sea ice extent.
  • Antarctic sea ice extent in July was above average, 4.8 percent above the 1979-2000 average—resulting in the largest July sea ice extent on record.
  • According to Australia’s Bureau of Meteorology, the continent received an average of 34.4 mm (1.35 inches) of precipitation during July 2010—this is 55 percent above the 1961-1990 average and the highest value since 1998.

Scientists, researchers and leaders in government and industry use NOAA’s monthly reports to help track trends and other changes in the world’s climate. This climate service has a wide range of practical uses, from helping farmers know what and when to plant, to guiding resource managers with critical decisions about water, energy and other vital assets.

A new record low maximum temperature set & snow comes to the mountains

Denver has record setting cool temperatures and snow arrives in the Rocky Mountains.  Image courtesy Victor Lewis.
Denver has record setting cool temperatures and snow arrives in the Rocky Mountains. Image courtesy Victor Lewis.

While some parts of the nation experience record setting heat, on Thursday Denver had the opposite problem. The high temperature as measured at Denver International Airport reached a mere 64 degrees. This was two degrees below the previous record low maximum temperature of 66 degrees for this date set in 1925 and previous years. That is also an amazing 24 degrees below the normal temperature for this time of year!

Here in Thornton, we were even cooler than the official temperature on Thursday as the mercury climbed to a mere 61.3 degrees! 

The unseasonably cold weather has also brought an unusual sight to the Colorado mountains in July – snow! Some northern parts of the Rocky Mountains in the state above 12,000 feet received a couple inches of snow.

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

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.

17 and still going – the heat wave continues

17 days - the 90 degree streak continues.This is beginning to sound like a broken record – pun intended. 🙂 As for Tuesday our streak of consecutive 90 degree days hit 17, moving us into a tie for second place. Assuming today reaches 90 degrees or more – and it almost certainly will – we will then tie the record that has been set twice previously (in 1901 and 1874).

An end in sight? Not yet. High pressure continues to hold over the area and temperatures are most likely going to actually climb to near 100 on Friday and through the weekend. Beyond that it is hard to say but things aren’t looking good to cool down anytime soon.

Certainly this streak is significant but we haven’t reached records for “hottest summer” just yet. Thus far we have had 34 days this year of 90+ degree temperatures. The number 10 slot for most 90+ degree days in a summer is held by 1960 when there were 50 days. The most? 2000 when there were 61.

Click here to view the updated statistics about our current streak and historical streaks.

16 days with 90+ degrees, the record certain to be broken

As on Monday, Denver has seen 16 consecutive days with 90 degrees or higher temperatures.  There was some hope the streak might be broken today but that quickly vaporized as we reached 95 degrees.

The current streak moves into a tie for fourth (with 2000).  The record of 18 days consecutive set in 1901 and 1874 is looking to be sure to be broken before the heat eases.  The next couple of days will see us remain in the mid 90’s and by Thursday and Friday we will be in the upper 90’s (possibly 100).  The weekend shows no relief with temps well into the 90’s as well.  At the current time it looks like we will thouroughly eclipse the 18 day record and there is no end in sight at this time.

Click here to view the updated statistics about our current streak and historical streaks.

12 days and counting – the 90 degree streak continues

The 90 degree streak continues.As of today, Thursday, we are at 12 consecutive days with 90 plus degrees.  Unfortunately there doesn’t appear to be an end in sight although some coming days may drop just below the 90 degree mark.

Friday we can expect 91 degrees, Saturday 93, and Sunday 94.  Monday is currently looking to be around 90 so maybe the streak will end then – keep your fingers crossed! Continue reading 12 days and counting – the 90 degree streak continues