Typically November is a quiet weather month with plenty of nice, fall days but it can also turn wet with plenty of snow and moisture. Just like Forest Gump’s proverbial box of chocolates, you never quite know what you are going to get.
Looking into the weather history books, we see that November is actually Denver’s second snowiest month, second only to March (April is third). Historically we average 10.7 inches of snow during the month.
One little known fact… November is the area’s least sunny month, tying with May with only 64 percent sunshine. September is the sunniest month with sunshine 74 percent of the time.
Get all the details on Denver’s November weather including a look back through history, a recap of last year and the statistics in our November weather preview.
The City of Thornton wants residents to be prepared for the coming cold weather.
As we have been covering all week, by the governor’s declaration this is Winter Weather Preparedness Week in Colorado. The City of Thornton has gotten on board with information to help the city’s residents prepare themselves for the coming season.
Thornton has become much more ‘weather aware’ in recent years and we applaud them for that. Weather has a direct impact on everyone’s lives, too often with deadly effects, and it is important that people are aware of the dangers it presents.
We do have to make note of a couple of things on the page.
First, there is no link to ThorntonWeather.com. We are not affiliated with the city in any way however we are the only source of truly local weather news and information. The city must be careful of who they put out there as a recommended resource but ThorntonWeather.com is well-established having been around for more than five years and being well known and highly regarded in the community. We pride ourselves on the wealth of information we provide, an amount that far surpasses any other.
Denver saw a big change in the weather in a very short period of time. Click the image for a slideshow of images from the snowstorm.
The weather in Colorado is famously variable and in a span of a few short days this was fully evident. We went from record high temperatures to a winter-like snowstorm and back to sunny skies in four days.
On Monday, October24, Denver set a record high temperature of 80 degrees, besting the record high for the date of 79 degrees last set in 1999. Thornton was just a touch cooler for the day with a high of 79 degrees.
Tuesday was a day of transition as we started with sunny skies but clouds rolled in during the afternoon and rain was falling by the evening. As darkness descended and temperatures fell, the rain changed to snow and we started our first snowstorm of the season.
In the Denver metro area, snow totals ranged from a few inches to as many as 9 in the western and northwestern suburbs. Denver International Airport recorded 8.5 inches, more than double the 4.1 inch average for the month of October. Here in Thornton, we lagged a bit with 6.6 inches of the white stuff.
Have broken branches to get rid of? The City of Thornton is holding a special tree limb drop off event on Saturday. Click here for details
Across Thornton and much of the Front Range, the heavy wet snow caused its share of problems. Many trees had yet to lose their leaves and branches broke under the weight of the snow. Power outages were seen across the region including many in Thornton.
While the storm moved out before nightfall Wednesday, it left clearing skies which led to bitterly cold temperatures. Denver International Airport recorded an early morning low of 14 degrees, the coldest temperature the city has seen since March 5th. Here in Thornton we dropped to a low of 12.8 degrees.
The latest forecasts show we are in for a gradual warm up but one that will keep temperatures below normal through the weekend. Beyond that, we may be getting our next shot of snow as soon as late in the day next Tuesday.
The video below was captured by our west facing webcam. You can see as the snow builds the trees start sagging and struggle under the weight of the snow.
Strengthening La Niña conditions in the Pacific could lead to another dry winter on the Colorado Front Range according to the winter 2011 / 2012 outlook released by NOAA. However, as we well know, Mother Nature is never consistent and other factors could give us some help.
While temperatures in the Equatorial Pacific Ocean are indeed cooler than normal – and getting cooler – at this point they remain warmer than they were last year at this same time. This does help us hold out some hope that the winter won’t be as dry as last year.
It should also be noted that the effects of La Niña and El Niño in Colorado are much harder to predict and less consistent than in other places in the nation. Our location near the middle of the country with the monstrous Rocky Mountains adjacent to us oftentimes throws a wrench in the works.
U.S. dealt another La Niña winter but ‘wild card’ could trump it Devastating drought in Southern Plains likely to continue
NOAA's winter 2011 temperature outlook. Click the image for a larger view.
The Southern Plains should prepare for continued drier and warmer than average weather, while the Pacific Northwest is likely to be colder and wetter than average from December through February, according to the annual Winter Outlook released today by NOAA.
For the second winter in a row, La Niña will influence weather patterns across the country, but as usual, it’s not the only climate factor at play. The ‘wild card’ is the lesser-known and less predictable Arctic Oscillation that could produce dramatic short-term swings in temperatures this winter.
NOAA expects La Niña, which returned in August, to gradually strengthen and continue through the upcoming winter. It is associated with cooler than normal water temperatures in the tropical Pacific Ocean and influences weather throughout the world.
“The evolving La Niña will shape this winter,” said Mike Halpert, deputy director of NOAA’s Climate Prediction Center. “There is a wild card, though. The erratic Arctic Oscillation can generate strong shifts in the climate patterns that could overwhelm or amplify La Niña’s typical impacts.”
The Arctic Oscillation is always present and fluctuates between positive and negative phases. The negative phase of the Arctic Oscillation pushes cold air into the U.S. from Canada. The Arctic Oscillation went strongly negative at times the last two winters, causing outbreaks of cold and snowy conditions in the U.S. such as the “Snowmaggedon” storm of 2009. Strong Arctic Oscillation episodes typically last a few weeks and are difficult to predict more than one to two weeks in advance.
NOAA's winter 2011 precipitation outlook. Click the image for a larger view.
With La Niña in place Texas, Oklahoma, New Mexico and parts of surrounding states are unlikely to get enough rain to alleviate the ongoing drought. Texas, the epicenter of the drought, experienced its driest 12-month period on record from October 2010 through September 2011.
Stormy periods can occur anytime during the winter season. To improve the ability to predict and track winter storms, NOAA implemented a more accurate weather forecast model on Oct.18. Data gathered from the model will support local weather forecast office efforts to prepare for and protect the public from weather events. This service is helping the country to become a Weather-Ready Nation at a time when extreme weather is on the rise.
According to the U.S. Winter Outlook (December through February) odds tilt in favor of:
Pacific Northwest: colder and wetter than average. La Niña often results in below-average temperatures and increased mountain snow in the Pacific Northwest and western Montana during the winter months. This may set the stage for spring flooding in the Missouri River Basin;
California: colder than average and wetter than average conditions in northern California and drier than average conditions in southern California. All of the southern part of the nation are at risk of having above normal wildfire conditions starting this winter and lasting into the spring;
Northern Plains: colder and wetter than average. Spring flooding could be a concern in parts of this region;
Southern Plains and Gulf Coast States: warmer and drier than average. This will likely exacerbate drought conditions in these regions;
Florida and south Atlantic Coast: drier than average, with an equal chance for above-, near-, or below-normal temperatures. Above normal wildfire conditions;
Ohio and Tennessee Valleys: wetter than average with equal chances for above-, near-, or below-average temperatures. Potential for increased storminess and flooding;
Northeast and Mid-Atlantic: equal chances for above-, near-, or below-normal temperatures and precipitation. Winter weather for these regions is often driven not by La Niña but by the Arctic Oscillation. If enough cold air and moisture are in place, areas north of the Ohio Valley and into the Northeast could see above-average snow;
Great Lakes: colder and wetter than average;
Hawaii: above-average temperatures in the western islands with above normal precipitation during the winter. Some drought recovery is expected across the state with Kauai and Oahu having the best potential for full recovery.
Alaska: colder than average over the southern half of the state and the panhandle with below average precipitation in the interior eastern part of the state.
This seasonal outlook does not project where and when snowstorms may hit or provide total seasonal snowfall accumulations. Snow forecasts are dependent upon winter storms, which are generally not predictable more than a week in advance.
August 2011 brought record-setting heat to Denver.
You didn’t need to know the statistics to be well aware that August was unusually warm and dry in Thornton and Denver. The month saw little precipitation and record setting temperatures became commonplace, particularly in the latter half of the month.
For moisture, Denver recorded a mere 0.30 inch in the rain bucket at Denver International Airport. This was 1.27 inches below the normal of 1.57 inches. The month barely missed making the list of top 10 driest Augusts by only 0.02 inch.
Afternoon thunderstorms were seen 12 times at DIA but only one brought measurable precipitation. The storms were typically high-based and yielded little more than wind.
Thornton followed DIA’s lead with little precipitation as we only saw 0.27 inch during the month.
Temperatures were the real weather story for August 2011 as rather than seeing cooler temperatures through the month like normal, the mercury stayed exceedingly high.
Overall DIA saw an average temperature of 77.0 degrees making it the hottest August on record. This surpassed the previous record August from 1937 when 76.8 degrees was seen. The month also went into the record books as the sixth warmest month ever recorded in Denver.
Temperatures ranged from a high of 99 degrees on the 25th down to a low of 55 degrees on the 20th. Through August 31st, Denver had seen 71 consecutive days of 80 degrees or warmer weather. This easily bested the previous longest streak of 59 days set in 2002.
Seven individual temperature records were set during the month. These included a tied record high on the 18th of 98 degrees last set in 1986; the 23rd tied the record high of 98; the 24th set a new record high for the date of 98 degrees; the 25th set a new record high of 99 degrees; the 28th set a record high of 96 degrees; the 28th saw a record high minimum of 67 degrees; the 31st tied the record high of 98 degrees.
Here in Thornton we were certainly hot but not nearly as much so as DIA. We recorded an average temperature of 74 degrees. Our warmest reading was 96.2 degrees and our coolest was 54. In all we saw 20 days with temperatures of 90 degrees or warmer.
While the high temperatures were notable, DIA benefits from later arrival of the typical afternoon thunderstorms due to its location further east of the rest of Denver. This certainly aided in the airport recording higher temperatures than anywhere else in the metro area. For more on that story, check out the Denver Weather Examiner.
CLIMATE REPORT...CORRECTED
NATIONAL WEATHER SERVICE BOULDER, CO
430 PM MDT FRI SEP 2 2011
...................................
...THE DENVER CO CLIMATE SUMMARY FOR THE MONTH OF AUGUST 2011...
CLIMATE NORMAL PERIOD 1981 TO 2010
CLIMATE RECORD PERIOD 1872 TO 2011
WEATHER OBSERVED NORMAL DEPART LAST YEAR'S
VALUE DATE(S) VALUE FROM VALUE DATE(S)
NORMAL
................................................................
TEMPERATURE (F)
RECORD
HIGH 105 08/08/1878
LOW 40 08/26/1910
08/25/1910
08/24/1910
HIGHEST 99 08/25 105 -6 97 08/22
LOWEST 55 08/20 40 15 47 08/17
AVG. MAXIMUM 92.7 87.2 5.5 88.6
AVG. MINIMUM 61.3 57.9 3.4 59.0
MEAN 77.0 72.5 4.5 73.8
DAYS MAX >= 90 22 11.5 10.5 12
DAYS MAX <= 32 0 0.0 0.0 0
DAYS MIN <= 32 0 0.0 0.0 0
DAYS MIN <= 0 0 0.0 0.0 0
PRECIPITATION (INCHES)
RECORD
MAXIMUM 5.85 1979
MINIMUM 0.02 1924
TOTALS 0.30 1.57 -1.27 1.05
DAILY AVG. 0.01 0.05 -0.04 0.03
DAYS >= .01 3 8.6 -5.6 6
DAYS >= .10 1 4.3 -3.3 3
DAYS >= .50 0 1.2 -1.2 1
DAYS >= 1.00 0 0.3 -0.3 0
GREATEST
24 HR. TOTAL 0.27 08/03 TO 08/03 0.68 08/01/10 TO 08/01/10
SNOWFALL (INCHES)
RECORDS
TOTAL 0.0 NO SNOW EVER RECORDED IN AUGUST
TOTALS 0.0 NO SNOW EVER RECORDED IN AUGUST
DEGREE_DAYS
HEATING TOTAL 0 5 -5 0
SINCE 7/1 0 11 -11 3
COOLING TOTAL 382 244 138 280
SINCE 1/1 863 688 175 762
FREEZE DATES
RECORD
EARLIEST 09/08/1962
LATEST 06/08/2007
EARLIEST 10/07
LATEST 05/05
..................................................
WIND (MPH)
AVERAGE WIND SPEED 8.8
RESULTANT WIND SPEED/DIRECTION 3/202
HIGHEST WIND SPEED/DIRECTION 39/180 DATE 08/31 38/190 08/12
HIGHEST GUST SPEED/DIRECTION 48/200 DATE 08/31 45/340 08/12
08/16
SKY COVER
POSSIBLE SUNSHINE (PERCENT) MM (NO LONGER RECORDED)
AVERAGE SKY COVER 0.50
NUMBER OF DAYS FAIR 4
NUMBER OF DAYS PC 26
NUMBER OF DAYS CLOUDY 1
AVERAGE RH (PERCENT) 41
WEATHER CONDITIONS. NUMBER OF DAYS WITH
THUNDERSTORM 0 MIXED PRECIP 0
HEAVY RAIN 1 RAIN 1
LIGHT RAIN 8 FREEZING RAIN 0
LT FREEZING RAIN 0 HAIL 0
HEAVY SNOW 0 SNOW 0
LIGHT SNOW 0 SLEET 0
FOG 4 FOG W/VIS <= 1/4 MILE 1
HAZE 5
- INDICATES NEGATIVE NUMBERS.
R INDICATES RECORD WAS SET OR TIED.
MM INDICATES DATA IS MISSING.
T INDICATES TRACE AMOUNT.
August 2011 goes into the record books as the hottest August ever.
As August 2011 came to a close and the numbers were crunched, they revealed what we already knew – it was one hot month! In fact, in the final tally Denver tied or set 10 different records during the month.
From the National Weather Service, here is the list of records:
Denver’s record setting August 2011 – From the National Weather Service:
August 2011 hottest Denver August with average temperature 77.0 degrees. Previous record 76.8 degrees set in 1937.
August 2011 became the 6th hottest Denver month. Hottest was 77.8 during July 1934.
71 consecutive days above 80 degrees through August 31st. Previous streak record 59 days set in 2002.
Tied most August 90 degree days with 22. Tied with 1995 and 1960.
18th – tied record high 98 last 1986
23rd – tied record high 98 last 2009
24th – record high 98 old 97 in 1936
25th – record high 99 old 96 in 1913
28th – record high 96 old 94 last 1969
28th – record high minimum temperature 67 old 66 last 2010
31st – tied record high 98 last 1960
How did Thornton compare?
Here in Thornton we were a bit cooler than what Denver’s official measurements at DIA recorded. This is in large part due to our location further to the west.
When the typical afternoon cloud cover and thunderstorms develop in the summer, it can take more than an hour for those conditions to reach DIA. As a result the station gets the benefit of a longer period of daytime heating. This works in Thornton’s favor as we stay a bit cooler.
For us, our overall average temperature for the month was 74.0 degrees – a full three degrees cooler than DIA. That doesn’t mean it wasn’t hot for us as we recorded 20 days with 90 degree or hotter weather and every day saw 80 degrees or higher.
Are the Denver weather records really valid? Check out the stories from Examiner.com below for why they may not be.
As temperatures start to drop, September reminds us that summer is at an end and fall is now here. Sunshine is predominant though as the month actually has the highest percentage of sun out of any month. Sunny days and clear, cool nights are the standard weather pattern for the month.
Normal highs on the first of the month are 82 degrees with a low of 53. By the end of the month we see those high temperatures drop to an average of 73 and the lows get to a chilly 42. Overall the month averages 63.4 degrees.
Denver has broken or tied seven different warm weather temperature records this month.
With the arrival of August we typically see a decrease in daytime high temperatures making the month one of the more pleasant in Denver. This year however that has not been the case as we have seen records fall and we appear on our way into the record books with one of the hottest Augusts on record.
With three days remaining in the month, Denver has tied or broken seven warm weather temperature marks so far. These include:
August 18 – Denver ties the record high temperature for the date of 98°. The mark was last set in 1986.
August 23 – The high temperature at DIA hits 98°. This ties the record high for the date last set in 2009.
August 24 – Denver hits 98°. Breaks old record of 97° set in 1936
August 25 – Denver reaches 99°. Breaks old record of 96° set in 1913. Also marks the latest date in the year that Denver’s temperature reached 99 degrees. Previously the date was August 16.
August 28 – Denver tops out at 96°. Breaks old record of 94° set in 1969 and previous years
August 28 – The mercury only drops to 67° over the 24 hour period. This sets a new record high minimum for the date. The previous record was 66° set in 2010 and previous years.
One important aspect to these records is that most of those marks would never have been reached were it not for the measurements being taken at DIA. Other station’s closer to the historical Denver weather sites near Stapleton and downtown never approached as warm of temperatures.
One high temperature record was tied and another broken over the past two days.
If you thought with the kids heading back to school summer was coming to an end Mother Nature has other plans. The hot weather continues and in the past two days it has reached record setting heights.
Yesterday, August 23rd, Denver hit a high temperature of 98 degrees as measured at Denver International Airport. This tied the previous record high for the date last set in 2009 and previous years. Thornton fared a bit cooler as we ‘only’ reached 96 degrees.
Despite forecasts calling for cooler temperatures today, the mercury just kept on climbing and topped out at 98 degrees at 3:17pm. This broke the old record high temperature of the date of 97 degrees set 75 years ago in 1936. Mercifully, Thornton again was cooler with a high of 95 degrees.
As with all Denver records since 1995 when the National Weather Service moved the city’s official monitoring station to DIA, the records come with an asterisk. That move of 12 miles has resulted in consistently higher temperatures than what is seen at the historical site at Stapleton or closer to downtown.
Another official station, located at Denver City Park, provides evidence of this over the last two days. The station is much closer to where historical records were taken and thus can be more accurately used to compare to the past.
That station recorded a high of 97 degrees yesterday and 95 degrees today. Neither of these would be records had Denver’s station not made the move to a different microclimate at DIA.
This video screen capture shows the stage at the Indianapolis State Fair as it collapsed. Watch the video below. (YouTube / JSilas7)
Winds alone are not normally associated with the loss of life but a sad reminder of the dangers was seen at the Indianapolis State Fair on Saturday. Powerful thunderstorm winds downed a stage killing five people and injuring dozens while officials appeared to ignore warnings of the impending danger.
The Natural Disasters Examiner wrote in a story on Monday that the warning signs for severe weather in central Indiana were readily apparent as early as two days before the storm.
The National Weather Service discussed the thunderstorm and high wind dangers in its Hazardous Weather Outlook multiple times. A Severe Thunderstorm Watch was issued hours before and a Warning 10 minutes before.
Despite this, officials at the fair failed to make a timely decision to cancel the Sugarland concert. When the winds, estimated at 50 to 70mph struck, it only took a matter of seconds for the stage’s rigging to collapse. Five people died and more than 40 were injured due to their failure.
The tragedy should serve as a reminder to everyone to pay attention to changing weather. Do not ignore weather watches and warnings, no matter what others are doing. The life you save may be your own.
The video below captures the event with shocking clarity. It may be disturbing for some so viewer discretion is advised.
Our hearts and prayers go out to all those affected by the tragedy.
Weather, natural disasters & climate news and information.
Typically November is a quiet weather month with plenty of nice, fall days but it can also turn wet with plenty of snow and moisture. Just like Forest Gump’s proverbial box of chocolates, you never quite know what you are going to get.
As temperatures start to drop, September reminds us that summer is at an end and fall is now here. Sunshine is predominant though as the month actually has the highest percentage of sun out of any month. Sunny days and clear, cool nights are the standard weather pattern for the month.