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Weather History

April 8 to April 14 – This Week in Denver Weather History

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This Week In Denver Weather History
April 8 to April 14 - This Week in Denver Weather History

April in Denver can bring a wide array of weather conditions, many of which appear in their most extreme form. Our look back at this week in Denver weather history demonstrates this with everything from major snowstorms to damaging windstorms to even a tornado.

From the National Weather Service:

6-8

In 1973…a major spring snow storm dumped 11.6 inches of snowfall over metro Denver. North wind gusts of 30 to 35 mph produced some blowing snow. Most of the heavy wet snow… 10.1 inches…fell on the 7th when temperatures remained in the 20’s. Snow accumulated on the ground to a maximum depth of 9 inches. Low temperature of 5 degrees on the 8th was a new record minimum for the date and the lowest for so late in the season.

7-9

In 1913…heavy snowfall totaled 10.9 inches in downtown Denver behind a cold front. Most of the snow fell on the 8th. Northeast winds were sustained to 35 mph with gusts to 38 mph on the 9th.

In 1935…moderate dust blew into the city around 9:00 pm on the 7th and persisted until early afternoon on the 9th. Southeast winds were sustained to around 20 mph on the 7th and 8th. Winds shifting to the west at sustained speeds to 20 mph cleared the dust from the air on the 9th.

7-12

In 1959…snow falling over a 5-day period totaled 20 to 30 inches just east of the mountains…while over the plains blizzard conditions closed schools and blocked highways. The second big storm in two weeks dumped 16.4 inches of snowfall on Stapleton Airport with the most…11.6 inches… Occurring on the 8th. East winds gusted to 37 mph on the 9th. Temperatures dipped into the single digits on the mornings of the 7th and 12th when 7 degrees were registered. Low temperature records for the dates were set on the 9th…10th…and 12th. The cold temperatures caused streets to glaze with ice…resulting in the death of a pedestrian who was struck by a car in Denver. Three people died from heart attacks while shoveling the heavy… Wet snow.

8

In 1885…dense smoke polluted the air until noon.

In 1887…south winds were sustained to 42 mph.

In 1890…northwest winds were sustained to 48 mph with gusts as high as 60 mph.

In 2005…a mixture of strong pressure gradient winds coupled with thunderstorm outflow winds produced high winds across metro Denver. The high winds downed power lines and knocked out electricity to about 19 thousand customers on the east side of metro Denver. High wind reports included gusts to 68 mph in Longmont…61 mph near Castle Rock…59 mph at Centennial Airport…and 54 mph at Denver International Airport.

8-10

In 1999…a windstorm caused 20 million dollars in damage along the Front Range urban corridor from Fort Collins south to Pueblo and to the east over the plains…making the storm equal to the costliest windstorm ever…which occurred in Boulder on January 17…1982. In metro Denver… Several homes were damaged as shingles were blown off roofs. Large pieces of a roof torn off a strip mall in Lakewood damaged several cars in a parking lot. Most of the damage to homes consisted of broken fences…awnings…doors…and windows. Scores of automobiles suffered broken or cracked windshields and paint damage from flying debris. Multiple accidents were triggered as several tractor-trailer rigs were blown on their sides by the strong cross-winds. Blowing dust and dirt caused near zero visibilities at times. Both I-25 and I-76 were closed north and northeast of Denver. State Highway 93 was closed between Golden and Boulder. Several trees…power poles…and power lines were downed…causing a number of outages as well as sparking a few small grass fires. Highest wind gusts reached 112 mph atop Niwot Ridge near the Continental Divide west of Boulder…102 mph at Wondervu…100 mph at the National Center for Atmospheric Research mesa lab in Boulder…98 mph at the national wind technology center near Broomfield…96 mph on Rocky Flats…92 mph at Jefferson County Airport near Broomfield and on the University of Colorado campus in Boulder…and 90 mph at Highlands Ranch in southwest metro Denver. Winds gusted to 48 mph at Denver International Airport.

9

In 1950…strong southwest winds gusting to 58 mph reduced the visibility to 1 mile in blowing dust at Stapleton Airport. Scattered minor wind damage…consisting of falling tree branches and damage to signs…occurred across metro Denver.

In 1989…6 to 12 inches of snow fell at many locations in the Front Range foothills. Boulder received 6 to 8 inches. Five inches (5.0 inches) of snow fell at Stapleton International Airport…causing 2 hour flight delays. I-25 south of Denver was closed for 4 hours due to a 100- car traffic pileup. North winds gusted to 33 mph at Stapleton International Airport where the maximum snow depth on the ground was only 3 inches due to melting.

Continue reading April 8 to April 14 – This Week in Denver Weather History →

Weather History

March 25 to March 31 – This Week in Denver Weather History

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This Week In Denver Weather History
March 25 to March 31 - This Week in Denver Weather History

In stark contrast to the extremely dry and mild month we are experiencing now, March is normally known for its snow. In our look back at this week in Denver weather history we see many significant snow events that have occurred in the past and are much more representative of Denver’s March weather.

From the National Weather Service:

23-25

In 1891…rain changed to snow and totaled 8.8 inches in downtown Denver. Most of the snow fell on the 24th. Winds were light.

In 1964…heavy snowfall of 5.8 inches was measured at Stapleton International Airport. North-northeast winds gusted to 21 mph behind a cold front.

24-25

In 1904…west Bora winds sustained to 40 mph with gusts to 55 mph warmed the temperature to a high of 49 degrees on the 24th. Overnight…a cold front produced 4.5 inches of snow. The high temperature was only 34 degrees on the 25th.

In 1955…a vigorous cold front with winds sustained to 34 mph and gusts to 39 mph briefly reduced the visibility to 2 miles in blowing dust at Stapleton Airport. Post-frontal heavy snowfall totaled 9.5 inches at Stapleton Airport where the maximum snow depth on the ground was 7 inches.

24-26

In 1959…the second major spring storm in less than a week dumped 10 to 20 inches of wet snow across northeastern Colorado. Snowfall totaled 14.3 inches at Stapleton Airport where north winds gusted to 36 mph…causing near-blizzard conditions with visibilities frequently reduced to 1/2 mile in snow and blowing snow. Many travelers were marooned when trains…planes…and buses were unable to make their schedules. Utility lines were again damaged as a result of the storm.

25

In 1874…the wind blowing in gusts from the west-northwest filled the air with dust so dense that only the houses in the immediate neighborhood of the weather station could be recognized. The brisk winds continued through the afternoon.

In 1886…heavy snowfall of 6.5 inches occurred in the city.

In 1896…northwest winds sustained to 58 mph with gusts to 65 mph warmed the temperature to a high of 70 degrees.

In 1911…west winds were sustained to 43 mph. The Chinook winds warmed the temperature to a high of 65 degrees.

In 1925…northwest winds were sustained to 41 mph with gusts to 46 mph.

In 1950…strong Chinook winds gusted to 50 mph at Stapleton Airport.

In 1976…3.4 inches of snow fell at Stapleton International Airport where northeast winds gusted to 46 mph. The strong winds at 20 to 35 mph all day produced a rare “snirt” storm when blowing dust and dirt became mixed with snow and blowing snow reducing the visibility to as low as 1/4 mile at Stapleton International Airport.

In 1984…1 to 4 inches of new snow fell across metro Denver. Icy roads contributed to many accidents. The most hazardous conditions occurred in the foothills west of Denver. Both I-70 and U.S. 40 were closed at the height of the Sunday afternoon ski rush…causing delays of many hours. Snowfall totaled only 1.0 inch at Stapleton International Airport with only a trace on the ground due to melting.

In 1988…high winds in the mountains spread over metro Denver. A wind gust to 75 mph was noted in Boulder where a traffic light was downed. Power outages were reported in Boulder County. Northwest winds to 46 mph were recorded at Stapleton International Airport.

Continue reading March 25 to March 31 – This Week in Denver Weather History →

Climatology, Thornton Weather, World Weather

April 2011 ends as 7th warmest on record for the globe; Denver warmer and drier than normal

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Global surface temperature Anomalies - April 2011. (NOAA)
Not only did Denver and Thornton see warmer than normal temperatures in April, so did the rest of the globe. Click the image for a larger version. (NOAA)

With the effects of La Nina still in full force the globe’s temperatures performed as forecasted during April 2011.  According to NOAA the month ranked as the seventh warmest April on record while Denver saw warmer and drier than normal conditions as well.

Denver saw an average temperature during the month of 48.4 degrees – 0.8 degree above normal.  Temperatures ranged from a record high of 84 degrees on the 2nd down to a low of 19 on the 4th of the month.  Fifteen days saw temperatures dip below the freezing mark which is four more than normal.

Here in Thornton we were slightly cooler with an average of 48.1 degrees for April.  Our high ranged from 86.3 degrees down to a low of 20.6 degrees.

The lack of precipitation and snowfall was one of the biggest stories of the month for the Mile High City.  A mere 1.07 inch of precipitation was recorded in Denver’s rain bucket which was 0.86 inch below the normal of 1.93 inches.

Snowfall was similarly dismal as only 1.2 inches of snow was recorded at Denver International Airport.  This was far below the normal of 9.1 inches for April which is historically our fourth snowiest month.  Through April 30, a mere 21.8 inches of snow has been recorded at Denver’s official monitoring site at Denver International Airport – the second worst snow season to date.

Thornton was a bit wetter than Denver as we recorded 1.54 inches of liquid precipitation.  In terms of snowfall we received only 1.5 inches, most of which (1.3”) fell on the 3rd of the month.

Overall the globe saw warm temperatures as well.  The combined land and ocean temperature average for the month was 57.76° F which was 1.06° above the 20th century average.  Taken separately the land surface temperature was 2.02° above normal and sea temperatures were 0.70° above normal.

April 2011 global climate summary – From NOAA:

The Earth experienced the seventh warmest April since record keeping began in 1880, as the climate phenomenon La Niña continued to be a significant factor. April’s annual Arctic sea ice extent was the fifth smallest since record keeping began in 1979, while the Antarctic sea ice extent was the fourth smallest.

The monthly analysis from NOAA’s National Climatic Data Center in Asheville, N.C., is part of the suite of climate services NOAA provides government, business and community leaders so they can make informed decisions.

Global Temperature Highlights – April

  • The combined global land and ocean average surface temperature for April 2011 was the seventh warmest on record at 57.76 F (14.29 C), which is 1.06 F (0.59 C) above the 20th century average of 56.7 F (13.7 C). The margin of error associated with this temperature is +/- 0.13 F (0.07 C).
  • Separately, the global land surface temperature was 2.02 F (1.12 C) above the 20th century average of 46.5 F (8.1 C), which was the sixth warmest April on record. The margin of error is +/- 0.20 F (0.11 C). Warmer-than-average conditions occurred across most of the southern United States and northern Mexico, much of central South America, Europe and Siberia. Cooler-than-average regions included most of Alaska, western Canada, the northwestern United States, southwestern Greenland and most of Australia.
  • The April global ocean surface temperature was 0.70 F (0.39 C) above the 20th century average of 60.9 F (16.0 C), making it the 11th warmest April on record. The margin of error is +/- 0.07 F (0.04 C). The warmth was most pronounced in the eastern Atlantic Ocean, the northwestern Pacific and across the Southern Hemisphere mid-latitudes.
  • The average temperature was the warmest on record for April across the United Kingdom. Germany reported its second warmest April since records began in 1881.

Global Temperature Highlights – Year-to-date

  • The combined global land and ocean average surface temperature for the year to date (January – April 2011) was 0.86 F (0.48 C) above the 20th century average of 54.8 F (12.6 C), making it the 14th warmest on record. The margin of error is +/- 0.16 F (0.09 C).
  • The year-to-date worldwide land surface temperature was 1.33 F (0.74 C) above the 20th century average — the 17th warmest such period on record. The margin of error is +/- 0.36 F (0.20 C). Warmer-than-average conditions were particularly felt across the southern half of Greenland, Siberia, northern Mexico, the southern United States and across Africa. Cooler-than-average regions included central Canada, the northern United States, western Russia, Kazakhstan, Mongolia, extreme southeast Asia and most of Australia.
  • The global ocean surface temperature for the year-to-date was 0.68 F (0.38 C) above the 20th century average and was the 11th warmest such period on record. The margin of error is +/-0.07 F (0.04 C). The warmth was most pronounced across parts of the most of the western Pacific Ocean, the tropical Atlantic Ocean, the North Atlantic near Greenland and Canada, and the southern mid-latitude oceans.
  • La Niña conditions continued to weaken in April for the fourth consecutive month, although sea-surface temperatures remained below normal across the central and eastern equatorial Pacific Ocean. According to NOAA’s Climate Prediction Center, La Niña will continue to have global impacts as the event continues to decline, but by late spring neither La Niña nor El Niño conditions are expected to prevail in the region.
  • Effective May 2, 2011, NOAA updated its monthly mean temperature dataset, which is used to calculate global land surface temperature anomalies and trends. The Global Historical Climate Network-Monthly (GHCN-M) version 3 dataset replaced GHCN-M version 2. Beginning with this month’s Global State of the Climate Report, GHCN-M version 3 is used for National Climatic Data Center climate monitoring products.  More information on this transition can be found at:http://www.ncdc.noaa.gov/ghcnm.

Polar Sea Ice and Precipitation Highlights

  • The average Arctic sea ice extent during April was 5.7 percent below average, ranking as the fifth smallest April since satellite records began in 1979.
  • The April 2011 Antarctic sea ice extent was 7.7 percent below average and was fourth lowest April extent since records began in 1979.
  • Northern Hemisphere snow cover extent during April ranked as the 15th smallest on record, while the snow cover extent over North America was the 10th largest and Eurasian snow cover was the fifth smallest April snow cover on record.
  • Average rainfall across Australia was 18 percent above average during April. However, for the first month since June 2010, below-average rainfall was reported in the states of Queensland, South Australia and New South Wales. This broke a streak of nine consecutive months with above-normal rainfall in those states.
National Weather, Natural Disasters

NOAA releases statistics highlighting devastating April tornado outbreak

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Tornado Tracks: April 24th through the 29th, 2011. (NOAA)
Tornado Tracks: April 24th through the 29th, 2011. (NOAA) Click the image for a larger view.

The devastating tornado outbreak that struck across the southern United States last month continues to be analyzed by the National Weather Service.  At latest county 326 people were killed and as many as 305 tornadoes resulted in in the outbreak.

What follows is NOAA’s latest update on the events:

From NOAA:

NOAA’s preliminary estimate is that there were 305 tornadoes during the entire outbreak from 8:00 a.m. EDT April 25 to 8:00 a.m. April 28, 2011. NWS created a table to provide clearer insight into the preliminary number of tornadoes. Each of the three categories in the table below has different levels of confidence/accuracy.

  • Eyewitness Reports are the least accurate/reliable because long-lived tornadoes like those in this outbreak tend to be reported multiple times. This artificially increases the number of tornadoes.
  • NOAA’s Estimate is based on expert analysis of the Eyewitness Reports compared with the details coming out of the Tornadoes Surveyed by NWS Weather Forecast Offices (WFO). It is the statistic NWS uses in public announcements since it is the best estimate at the time. The numbers will change (typically down) as WFOs complete their storm surveys.
  • Tornadoes Surveyed by WFOs is the latest confirmed number of tornadoes surveyed by the National Weather Service.
Preliminary Tornado Data Table
Date Eyewitness Reports NOAA’s Estimate Tornadoes Surveyed by WFOs (to date)
25-26 55 40 25
26-27 111 75 42
27-28 268 190 134
Total: 434 305 201
  • The NWS Storm Prediction Center issued severe weather outlooks five days in advance and tornado watches hours in advance.
  • NWS Weather Forecast Offices issued life-saving tornado warnings, with an average lead-time of 24 minutes. NWS issued warnings for more than 90 percent of these tornadoes.
  • NWS decision support for this event has been extensive. NWS Weather Forecast Offices in the affected areas of Arkansas, Tennessee, Mississippi, Alabama and Georgia advertised the potential for severe weather in the Tuesday through Wednesday timeframe since late last week. Local offices provided direct decision support services to meet the specific needs of local emergency manager partners and the general public. NWS Weather Forecast Offices issued Hazardous Weather Outlooks up to six days in advance noting the greater threat of strong, long-track tornadoes was expected.
  • The largest previous number of tornadoes on record in one event occurred from April 3-4, 1974, with 148 tornadoes.
  • NOAA will conduct a detailed analysis of tornado numbers using all available data to make any final determinations about records.  This typically takes months to complete.

There were approximately 326 fatalities during the entire outbreak from April 25 to April 28.

There were approximately 309 fatalities during the 24-hour-period from 8:00 a.m. April 27 to 8:00 a.m. April 28. This is currently the fifth deadliest day of tornadoes on record.

  • The Tuscaloosa-Birmingham tornado during the April 2011 event caused at least 65 fatalities. This tornado had a maximum width of 1.5 miles and a track 80 miles long
    • These are the most fatalities from a single tornado in the United States since May 25, 1955, when 80 people were killed in a tornado in southern Kansas with 75 of those deaths in Udall, Kansas.
    • The deadliest single tornado on record in the United States was the Tri-State tornado (Mo., Ill., Ind.) on March 18, 1925, when 695 died.

According to National Weather Service Weather Forecast Office Storm Survey teams, there were 24+ killer tornadoes in six states–Arkansas, Mississippi, Alabama, Georgia, Tennessee and Virginia–that caused an estimated 326 fatalities.

The National Weather Service Storm Survey teams have upgraded to EF-5 the tornado that hit Neshoba, Kemper, Winston, Noxubee Counties in Mississippi.  The Weather Service has documented three (3) EF-5 tornadoes in this outbreak.

EF-5 Tornado Locations

  • Northern Mississippi/Eastern Arkansas
    • Smithville in Monroe County
  • Mississippi (NEWLY UPGRADED TO EF-5 FROM E-4)
  • Northern/Central Alabama (WFO Birmingham Warning Area):
    • Hackleburg in Marion County

The following are the tornado fatality breakdowns by state:

  • 4 – Arkansas
  • 35 – Mississippi
  • 236 – Alabama
  • 31 – Tennessee
  • 5 – Virginia
  • 15 – Georgia

Note:  All numbers are based on combined NOAA and historical research records and current fatality estimates. The historical research records extend back to 1680.

Ongoing (preliminary) List of Tornadoes by EF Rating (EF0 to EF5):
EF-5 3
EF-4 11
EF-3 21
EF-2 47
EF-1 62
EF-0 57
Total: 201
National Weather, Natural Disasters

The South tries to recover amongst devastation of 2nd deadliest tornado outbreak on record

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Damage from an EF5 tornado that struck Smithville, Miss., on April 27, 2011.
Damage from an EF5 tornado that struck Smithville, Miss., on April 27, 2011. Click the image for a slideshow of the devastation. (NWS)

With entire towns reduced to rubble and damage spread across seven states, people in the southeastern United States began the long task of recovery.  The tornadoes that struck this past week claimed 341 lives and achieved the unwanted status as the 2nd deadliest single-day tornado outbreak in U.S. history.

President Barack Obama toured the devastated city of Tuscaloosa in Alabama yesterday saying, “I have never seen devastation like this. It is heartbreaking.”

The National Weather Service received 211 tornado reports during the outbreak, a number that will be reduced once duplicates are removed.  No matter the number of twisters, the results were nothing short of devastating.

One tornado that struck near Smithville, Mississippi has received an EF-5 rating – the highest possible.  Meteorologists estimate that twister packed winds of 205mph.  A tornado in Georgia was rated an EF-4 and at least five EF-3 tornadoes struck Alabama.  Weather service officials say they expect more twisters could receive the highest rating as they continue their investigation.

With 341 lives confirmed lost and the number expected to continue to grow, the outbreak ranks as the 2nd deadliest single-day outbreak on record.  It surpassed the “Super Outbreak” of 1974 and a 1932 outbreak in the Deep South.

Some are speculating the toll will grow enough for the event to become the worst in history, a truly nightmare scenario.  The Tri-State tornado on March 18, 1925 claimed the lives of 747 people.  One tornado alone in that outbreak tracked 234 miles across Missouri, Illinois and Indiana.

Slideshow: DigitalGlobe, NASA and Geoeye satellites provide view of tornado devastation
Slideshow: DigitalGlobe, NASA and Geoeye satellites provide view of tornado devastation

Obama has promised to speed federal aid to the region as governor’s in the hardest hit states declared states of emergency. “We can’t bring those who’ve been lost back. They’re alongside God at this point … but the property damage, which is obviously extensive, that’s something we can do something about,” the president said.

Damage estimates continue but an untold number of homes have been destroyed, certainly a number in the thousands.  Insured losses could reach between $2 billion and $5 billion which would push the disaster into the top 10 list of most expensive natural disasters in US history.

We are providing complete coverage of the tornado outbreak on Examiner.com.  Please visit the following links for more information.

Photo slideshows:

Related stories:

National Weather, Natural Disasters

Disaster strikes: Worst tornado outbreak in more than 30 years hits the South

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A tornado is seen ripping through Tuscaloosa, Alabama. View more images in the slideshow below.
A tornado is seen ripping through Tuscaloosa, Alabama. View more images in the slideshow below. (Credit: yfrog / bamawx)

A virtually unrivaled severe weather outbreak hit the southern United States yesterday bringing death and destruction.  The death toll from the event continues to climb and now ranks as the second worst since 1950.

The evaluation on the number of tornadoes and their power has begun by the National Weather Service.  The Storm Prediction Center recorded 164 reports but a number of those will be eliminated as duplicates of the same twisters.

Harold Brooks, a meteorologist with the SPC, told the Associated Press that he believed as many as 60 reports may be attributed to a single long-track tornado.  He further said that some may have achieved the EF-5 rating, the highest possible that generates winds in excess of 200mph.

Recovery efforts across the nation’s South continue as resources continue to arrive.  The Red Cross and other relief agencies were sending personnel from across the nation to help with search and rescue and to help with the distribution of water, food and other necessities.

  • Check out images and video of the tornadoes below

More than 1 million people were still without power this evening in Georgia, Alabama and Tennessee.  The Browns Ferry nuclear power plant west of Huntsville lost power from the storms but was able to safely shut down.

Alabama announced 11 more fatalities bringing the state’s losses to at least 195.  Overall at least 284 people across six states were killed making the disaster one of the worst tornado outbreaks in U.S. history.  Only the “Super Outbreak” of 1974 caused more deaths.

Photo slideshow - Death and destruction in Alabama in the wake of tornado outbreak.
Photo slideshow - Death and destruction in Alabama in the wake of tornado outbreak.

Tuscaloosa Mayor Walter Maddox said, “I don’t know how anyone survived.”  The mayor toured his city by helicopter and was stunned by the devastation. “We have neighborhoods that have been basically removed from the map,”Maddox said.

States of emergency were declared in Mississippi, Alabama, Arkansas, Tennessee, and Georgia.  President Barack Obama announced that he would speed federal aid to the disaster stricken region and would visit Alabama personally on Friday.

For complete coverage of the tornado outbreak, please visit the Natural Disasters Examiner.

Do you know what to do when severe weather strikes? Learn how to protect you and your family:

Thornton Weather

Thornton’s April weather can offer a little bit for everyone

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Thornton's April weatherApril 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.

Temperatures into the 70s and even the 80s aren’t entirely unheard of during the month.  Conversely, April is our third snowiest month so we certainly have the potential for plenty of the white stuff as well.

For a complete look at what the month of April may have in store, check our our April weather preview here.

Climatology

April weather in Denver – A bit of everything for everyone

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Denver's April weather previewApril 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 the complete details on Denver’s April weather here in our April weather preview.