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Weather History

November 27 to December 4 – This week in Denver weather history

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November 27 to December 4 - This week in Denver weather history
November 27 to December 4 - This week in Denver weather history

Cold, snow and wind are part of life on the Great Plains and we see all of those events have struck in abundance during this week in Denver weather history.  Many of the wind events were damaging and the snow accumulations significant.

From the National Weather Service:

25-28

In 1952…the average coldest 4-day period in November in the previous 81 years of record occurred.  Maximum temperatures of 19…15…21…and 25 degrees were recorded.  Minimum temperatures were below zero each day with readings of 7 below…6 below…5 below…and 6 below.

25-29

In 1985…dense fog with visibilities as low as 1/8 mile occurred on five consecutive days at Stapleton International Airport.  The fog was at times accompanied by light snow… Light freezing drizzle…or ice crystals.  Fog occurred all day on both the 26th and 29th.

28

In 1884…a windstorm during the afternoon produced northwest sustained winds to 46 mph.  Two wooden slats were blown out of the weather instrument shelter…and nearly all of the slats on the north and west sides were loosened.
 
In 1898…northwest winds were sustained to 50 mph with gusts as high as 80 mph.
 
In 1902…northwest winds were sustained to 40 mph with gusts to 48 mph.  The strong apparent Bora winds warmed the temperature to a high of only 40 degrees.
 
In 1904…northwest winds sustained to 44 mph with gusts to 58 mph warmed the temperature to a high of 58 degrees.
 
In 1927…strong west winds occurred in Boulder…causing widespread minor damage.  A wind gust to 65 mph was recorded at Valmont east of Boulder.  The west winds possibly produced a cyclonic twist.
 
In 1928…heavy snowfall totaled 7.0 inches over downtown Denver.
 
In 1957…a vigorous cold front produced north-northeast wind gusts to 54 mph at Stapleton Airport.  Light snow following the front totaled only 0.2 inch.
 
In 1970…strong Chinook winds reached 77 mph in downtown Boulder.
 
In 1978…wind gusts 60 to 90 mph were reported in and near the foothills.
 
In 1984…high winds of 60 to 80 mph occurred along the Front Range eastern foothills.  In Boulder…the high winds blew the roof off a service station.  Several trees were felled… Damaging some cars.  An elderly woman was injured when she was knocked down by a wind gust and blown 20 feet into some bushes.  Northwest winds gusted to 36 mph at Stapleton International Airport.
 
In 1994…winds gusted to 72 mph in Boulder.  No damage was reported.  Northwest winds gusted to 35 mph at Stapleton International Airport.

Continue reading November 27 to December 4 – This week in Denver weather history →

National Weather, Natural Disasters

Strong cold front brings tornadoes, damaging wind to Illinois and Wisconsin

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Path of EF2 tornado in Illinois on November 22, 2010. (NWS)
Path of EF2 tornado in Illinois on November 22, 2010. (NWS)

November is not normally the time of year for tornadoes, least of all in states in northern latitudes like Illinois and Wisconsin.  That however did not stop a mini-outbreak yesterday as at least two tornadoes struck and as many as seven were possible.

  • Watch video of the twister below

Severe thunderstorms were spawned yesterday by a strong cold front moving across the upper Midwest.  The twisters were the first in 26 years to strike the area in November – you have to go all the way back to November 9, 1984 to find the last one.

The National Weather Service has confirmed that the strongest of the tornadoes yesterday was an EF2 packing winds of 135mph.  It covered a path of 16.4 miles and had a maximum width of 200 yards.  The twister overturned a bus, caused significant damage to buildings and injured six people. 

Below you can see a video of the twister as it passed near Loves Park, Illinois.

Thornton Weather

Colorado mountains set to be slammed by major snowstorm

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A major winter storm will bring heavy snow to much of western Colorado.
A major winter storm will bring heavy snow to much of western Colorado. (NWS)

As travelers prepare to hit the road to visit friends and family for the Thanksgiving holiday, a major winter storm set to strike the Western Slope may cause problems.  Some areas will be measuring snow in terms of feet rather than the usual inches. 

A strong Pacific trough of low pressure will begin encroaching on western Colorado today followed by a cold front on Sunday.  These factors will combine to bring heavy snow to much of the western third of the state where Winter Storm Warnings have been posted.

The long-lasting storm will bring periods of heavy snow lasting from today through Wednesday.  The San Juans will bear the brunt through tomorrow followed by the Sawatch and Elk mountain ranges from Monday through Wednesday.  Areas farther north along the Rockies will also feel the effects. 

Here in Thornton and the Denver metro area things will be much calmer but also cooler, particularly on Wednesday and Thanksgiving Day.  High temperatures for those two days may not even reach the freezing mark.  At the current time it does appear we will remain dry so flying into and out of Denver International Airport (DIA) should not be a problem. 

Get the rest of the story on Examiner.com.Get more details including a look at current weather warnings for Colorado on the Denver Weather Examiner.

Climatology

Globe experiences eighth warmest October on record

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Warm and dry were the key words for Denver’s October weather and that same trend was also seen globally.  According to the National Climatic Data Center, October 2010’s average global temperature was the 8th warmest on record.  With an average temperature of 58 degrees, the month was nearly 1 degree warmer than average. 

The image below shows the areas that were warmer and cooler than the 1971 to 2000 average.

October 2010 global temperatures. (NOAA)
October 2010 global temperatures. (NOAA)

 From the National Oceanic and Atmospheric Administration:

Global Temperature Highlights

  • The combined global land and ocean average surface temperature for October 2010 was the eighth warmest on record at 58.07 F (14.54 C), which is 0.97 F (0.54 C) above the 20th century average of 57.1 F (14.0 C). The range associated with the combined temperature is +/- 0.14 F (0.08 C).*
  • The October worldwide land surface temperature was 1.64 F (0.91 C) above the 20th century average of 48.7 F (9.3 C) — the sixth warmest October on record. Warmer-than-average conditions were particularly felt across western Alaska, Canada, northeastern Africa, the Middle East, Kazakhstan and large portions of Russia. Cooler-than-average regions included most of Europe, Mongolia and much of Australia. The range associated with the land surface temperature is +/- 0.20 F (0.11 C).
    • According to the Bureau of Meteorology, Australia had its 10th coolest maximum temperatures on record for October with daytime maximum temperatures 2.12 F (1.18 C) below average. Statewide, both the Northern Territory and Queensland had their third coolest maximum temperatures since national records began in 1950.
  • The October worldwide ocean surface temperature was 0.72 F (0.40 C) above the 20th century average of 60.6 F (15.9 C) and was the 10th warmest October on record. The warmth was most pronounced across the Atlantic, western North Pacific and most of the Indian Ocean. The range associated with the ocean surface temperature is +/- 0.13 F (0.07 C).
  • For the year-to-date, the global combined land and ocean surface temperature of 58.53 F (14.73 C) was tied with 1998 as the warmest January–October period on record. This value is 1.13 F (0.63 C) above the 20th century average.
  • Moderate La Niña conditions continued in October, while sea surface temperatures remained below-normal across the central and eastern equatorial Pacific Ocean. According to NOAA’s Climate Prediction Center, La Niña is expected to strengthen and last at least into the Northern Hemisphere spring of 2011.

Polar Sea Ice and Precipitation Highlights

  • The average Arctic sea ice extent for October was 2.97 million square miles (7.69 million square km), which was 17.2 percent below average. This marks the third lowest October Arctic sea ice extent since records began in 1979 and the 14th consecutive October with below-average Arctic sea ice extent.
  • Antarctic sea ice began its annual retreat during October. October 2010 was the fourth largest sea ice extent on record (2.9 percent above average). The largest October sea ice extent occurred in 2006.
  •  According to Mexico’s National Weather Service (Servicio Meteorolológico Nacional), this October was Mexico’s driest since 1941.
  • North and west Amazonia in Brazil was in the midst of its worst drought in the past 40 years. In October, one of the Amazon River’s most important tributaries, the Black River, dropped to its lowest level of 44.7 feet (13.6 meters) since record keeping began in 1902.
Weather History

November 21 to November 27 – This week in Denver weather history

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November 21 to November 27 - This week in Denver weather history
November 21 to November 27 - This week in Denver weather history

Weather is a big part of the holidays.  With many people hitting the road to visit friends and family the weather can make or break those holiday plans.  Our look back at this week in Denver weather history shows a number of Thanksgivings when the weather put a damper on travel plans.

19-21

In 1979…a heavy snowstorm buried most of Colorado under at least a foot of snow.  Snowfall at Stapleton International Airport totaled 17.7 inches…the greatest snow depth since 1946.  Winds to 60 mph produced 5-foot drifts paralyzing the city as temperatures hovered in the 20’s.  While small airports closed…Stapleton remained open…but with long delays that snarled Thanksgiving holiday traffic.  Schools and businesses closed and postal deliveries were delayed. Almost all major highways leading out of Denver were closed to traffic for periods of time on the 20th and 21st.  Most of the snow…13.5 inches…fell on the 20th.  At Stapleton International Airport…north winds gusted to 35 mph on the 20th and to 38 mph on the 21st.

20-21

In 1898…snowfall totaled 4.0 inches in downtown Denver. Northeast winds were sustained to 48 mph with gusts as high as 60 mph behind an apparent cold front on the 20th… When temperatures plunged from a high of 66 degrees to a low of 9 degrees.  On the 21st the high was only 24 degrees and the low was 2 degrees.
 
In 1970…a wind gust to 94 mph was recorded at gold hill in the foothills west of Boulder.  Strong winds also swept across metro Denver.  Wind gusts reached 59 mph in downtown Boulder…while at Stapleton International Airport west- northwest winds gusted to 43 mph on the 21st.  Damage was minor.
 
In 1992…a large Canadian air mass moved into the state at the same time an upper level storm system approached from the west.  The combination of cold air at the surface and very moist air aloft produced heavy snow across the entire state.  Snowfall totaled 6.3 inches at Stapleton International Airport…where north winds gusted to 23 mph on the 20th.  Snow was heavier in the foothills…with 14 inches at Wondervu…13 inches at Aspen Springs…Conifer… Boulder…and Gross Reservoir…8 inches at Rollinsville… And 10 inches at Golden Gate Canyon and Morrison.
 
In 2007…a storm system brought moderate to heavy snowfall to portions of the urban corridor.  Storm totals included: 7 inches…3 miles south-southeast of Fort Collins…with 6 inches in Boulder and at Horsetooth inlet bay.  Elsewhere… Storm totals ranged from 2 to 5 inches.  Snowfall totaled 2.0 inches at the site of the former Stapleton International Airport.

Continue reading November 21 to November 27 – This week in Denver weather history →

Weather History

November 14 to November 20 – This week in Denver weather history

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November 14 to November 20 - This week in Denver weather history
November 14 to November 20 - This week in Denver weather history

Henry Fenton is probably not a name many folks are familiar with however he will forever be engrained in the Denver weather history books.  It was 139 years ago this week that Fenton made the first official Denver weather observations.

From the National Weather Service:

11-14

In 1970…heavy snowfall totaled 7.2 inches at Stapleton International Airport where northeast winds gusted to 22 mph on the 12th and 14th.  Most of the snow… 4.2 inches…fell on the 12th.

12-15

In 1909…light snowfall totaled 6.7 inches in downtown Denver over the 4 days.  This was the first measurable snowfall of the season.  Northeast winds were sustained to 15 mph on the 12th.

13-14

In 1925…heavy post-frontal snowfall totaled 6.4 inches overnight in downtown Denver.  Northwest winds were sustained to 27 mph with gusts to 29 mph on the 13th.
 
In 1974…northwest winds gusted to 52 mph at Stapleton International Airport…warming the temperature to 60 degrees shortly after midnight on the 13th.  A cold front cooled temperatures into the 20’s by late morning and produced snowfall of 3.7 inches.  The low temperature dipped to 14 degrees on the 14th.
 
In 1993…an upper level low pressure system combined with a weak but moist upslope flow to produce heavy snow across metro Denver.  Snowfall amounts averaged 6 to 8 inches with up to 16 inches in the foothills at the Eldora Ski Area. Snowfall totaled 6.0 inches at Stapleton International Airport where north winds gusted to only 20 mph on the 14th.  Most of the snow fell on the 14th.
 
In 1994…heavy snow developed rapidly along the Front Range urban corridor with the heaviest snow over northwest metro Denver.  Sixteen to 18 inches of snow fell in Boulder… Lafayette…and Louisville.  This was the second heavy snowfall over northwest metro Denver in 10 days.  Eleven to 14 inches of snow were measured from Longmont southward into Aurora.  Snowfall totaled 12.1 inches at Stapleton International Airport where northeast winds gusted to 29 mph on the 13th.  Most of the snow…9.0 inches…fell on the 14th.
 
In 1997…heavy snow fell overnight in portions of Jefferson and Boulder counties.  About 5.5 inches of snow were reported in Boulder…while 4 inches were measured 12 miles southwest of Morrison and 6 miles southwest of Golden. Snowfall totaled only 1.8 inches at the site of the former Stapleton International Airport.  Northeast winds gusted to 26 mph at Denver International Airport.

Continue reading November 14 to November 20 – This week in Denver weather history →

Climatology, Thornton Weather

Denver’s October 2010 wraps up dry and warm

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October 2010 ended up drier and warmer than normal.
October 2010 ended up drier and warmer than normal.

Following on what was a “top 10” warmest and driest September, October tried to follow suit but fell short of achieving record status.  Nevertheless, the month was considerably warmer and drier than normal. 

In terms of temperature the month ranked as the 11th warmest fall just 0.1 degree short of top 10 status.  The average temperature was 55.3 degrees; a considerable 4.3 degrees above normal.  Temperatures ranged from a high of 85 degrees on the 3rd down to a low of 20 on the 28th.  In all there were only two days when the mercury dipped to freezing or below; seven days below the normal nine we receive. 

Thornton was quite a bit cooler overall than Denver as we had an average temperature of 52.7 degrees.  Highs ranged from 84 degrees on the 4th down to 23.3 degrees on the 28th. 

As an interesting side note, it was just last October that we had our second coldest October on record.  The average temperature in October 2009 was a chilly 42.9 degrees and we had 17 days with temperatures at or below freezing! 

We suffered through another dry month which did spark a couple of wildfires.  A mere 0.54 inch of precipitation was recorded at the official monitoring site at Denver International Airport.  This was just barely more than half of the normal of 0.99 inch.  Most of the precipitation fell in the form of rain on the 12th when 0.34 inch was recorded.  Here in Thornton we were a bit wetter having recorded 0.73 inch of precipitation during the month. 

For the first time since 2003 no snow was recorded in Denver in October.  This is only the 15th time since 1882 that has happened.  On average we expect to receive 4.1 inches of the white stuff. 

See the official statistical summary from the National Weather Service below for more details.  Click here to view the monthly climate summary for Thornton.

CLIMATE REPORT
NATIONAL WEATHER SERVICE BOULDER, CO
205 PM MDT MON NOV 1 2010

................................... 

...THE DENVER CO CLIMATE SUMMARY FOR THE MONTH OF OCTOBER 2010...

CLIMATE NORMAL PERIOD 1971 TO 2000
CLIMATE RECORD PERIOD 1872 TO 2010

WEATHER         OBSERVED          NORMAL  DEPART  LAST YEAR'S
                 VALUE   DATE(S)  VALUE   FROM    VALUE  DATE(S)
                                          NORMAL
................................................................
TEMPERATURE (F)
RECORD
 HIGH              90   10/01/1892
 LOW               -2   10/29/1917
HIGHEST            85   10/03        90      -5       84  10/18
LOWEST             20   10/28        -2      22       17  10/10
AVG. MAXIMUM     69.7              66.0     3.7     54.7
AVG. MINIMUM     40.9              35.9     5.0     31.1
MEAN             55.3              51.0     4.3     42.9
DAYS MAX >= 90      0               0.0     0.0        0
DAYS MAX <= 32      0               0.3    -0.3        3
DAYS MIN <= 32      2               8.6    -6.6       17
DAYS MIN <= 0       0               0.0     0.0        0
PRECIPITATION (INCHES) 
RECORD
  MAXIMUM         4.17   1969  
  MINIMUM            T   1934
TOTALS           0.54              0.99   -0.45     1.36
DAILY AVG.       0.02              0.03   -0.01     0.04
DAYS >= .01         4               5.3    -1.3        8
DAYS >= .10         2                MM      MM        5
DAYS >= .50         0                MM      MM        0
DAYS >= 1.00        0                MM      MM        0
GREATEST
 24 HR. TOTAL    0.34   10/12 TO 10/12     0.39  10/20 TO 10/21       

SNOWFALL (INCHES)
RECORDS
 TOTAL           31.2   1969
TOTALS            0.0               4.1    -4.1       17.2             

DEGREE_DAYS
HEATING TOTAL     300               436    -136      676
 SINCE 7/1        335               582    -247      815
COOLING TOTAL       8                 0       8        0
 SINCE 1/1        870               696     174      533              

FREEZE DATES
RECORD
 EARLIEST     09/08/1962
 LATEST       06/08/2007
EARLIEST                        10/07
LATEST                          05/05
.................................................................

WIND (MPH)
AVERAGE WIND SPEED              9.1               9.6
RESULTANT WIND SPEED/DIRECTION   3/231            MM
HIGHEST WIND SPEED/DIRECTION    41/350  10/25    37/350  10/29/09
HIGHEST GUST SPEED/DIRECTION    51/350  10/25    54/200  10/05/09

SKY COVER
POSSIBLE SUNSHINE (PERCENT)   MM                                      

NUMBER OF DAYS FAIR            9
NUMBER OF DAYS PC             22
NUMBER OF DAYS CLOUDY          0

AVERAGE RH (PERCENT)     44

WEATHER CONDITIONS. NUMBER OF DAYS WITH
THUNDERSTORM              4     MIXED PRECIP               0
HEAVY RAIN                0     RAIN                       3
LIGHT RAIN                5     FREEZING RAIN              0
LT FREEZING RAIN          0     HAIL                       0
HEAVY SNOW                0     SNOW                       0
LIGHT SNOW                0     SLEET                      0
FOG                       2     FOG W/VIS <= 1/4 MILE      1
HAZE                      7                                           

-  INDICATES NEGATIVE NUMBERS.
R  INDICATES RECORD WAS SET OR TIED.
MM INDICATES DATA IS MISSING.
T  INDICATES TRACE AMOUNT.
Natural Disasters

Surveillance video shows trailers being overturned by tornado

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Crews pick up debris from Chickamauga Creek Oct. 27, 2010. (USACE/ Richard Scott)
Crews pick up debris from Chickamauga Creek Oct. 27, 2010. (USACE/ Richard Scott)

An extraordinary severe weather outbreak on Tuesday, October 26th brought Mother Nature’s fury to a large part of the nation stretching from Mississippi to Michigan.  Of the dozens of tornadoes reported that day, one ripped through Chickamauga Lock near Chattanooga, Tennessee and was captured on surveillance video.

  • Watch the amazing video below

The twister ripped through an area near Chickamauga Dam Tuesday evening where the Army Corps of Engineers is constructing the lock.  No injuries to the employees working at the sight were reported but the Corps said some barely escaped. 

The video, captured by a surveillance camera, initially gives no indication of the destruction that is about to come as conditions appear calm and vehicles are seen driving on a nearby road.  40 seconds into the video the winds and rain begin to pick up and 10 seconds later two construction trailers are flipped over and reduced to rubble.

Wayne Huddleston, project manager at Chickamauga Lock, said “The Corps is relocating personnel to other buildings on site and repairs and cleanup are ongoing.  We are extremely pleased that no people were hurt and that operations were not seriously affected by the storm.”

The video clearly shows why mobile homes and other structures without permanent foundations are never a safe place to take cover during severe weather.  Residents should always seek sturdier shelter in a permanent structure.

For all the latest on all types of natural disasters, be sure to check out the Natural Disasters Examiner.

Climatology

Denver’s November weather preview – Our 2nd snowiest and least sunny month

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Denver's weather in November can bring a wide variety of conditions. What can we expect in 2010? (iStockphoto / johnnyscriv)
Denver's weather in November can bring a wide variety of conditions. What can we expect in 2010? (iStockphoto / johnnyscriv)

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.

Thornton Weather

Denver’s frightening Halloween weather

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Many long-time Denver residents believe it always snows on Halloween. Is it fact or fiction?

As a kid growing up in Denver it always seemed like Mother Nature put a damper on our trick-or-treating.  Conventional wisdom in the Denver area is that it always seems to rain or snow on Halloween.  

But, is there any truth to this urban legend?  Or is this just one of those times where our memory doesn’t serve us quite right? 

This year it looks like we have nothing to worry about but  the National Weather Service has been kind enough to compile weather statistics just for Halloween.  As it turns out, the thought of snow and rain on Octboer 31st isn’t just in our minds! 

Get all the details in our Denver Halloween statistics and info page!  Click here!

Will it snow this Halloween?  Get the latest forecast here.