Public Information Statement
Issued by NWS Denver/Boulder, CO

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NOUS45 KBOU 240045

Public Information Statement
National Weather Service Denver/Boulder CO
645 PM MDT SAT SEP 23 2017

...This week in metro Denver weather history...

23-24 In 2000...the first snowstorm of the season brought heavy
        snow to areas in and near the foothills.  While the
        heaviest snow fell north of metro Denver...6 inches were
        measured in Boulder...4 inches at both Castle Rock and
        Morrison...but only 0.2 inch at the site of the former
        Stapleton International Airport where most of the
        precipitation fell as rain.  At Denver International
        Airport where drizzle and rain fell on the 23rd...
        snowfall during the early morning of the 24th was
        estimated at 2.1 inches due to melting.  The foothills
        west of Denver received more snow with 10 inches measured
        at Conifer...9 inches 11 miles southwest of Morrison...
        8 inches atop Crow Hill...7 inches at Chief Hosa...and
        5 inches at Ralston Reservoir.
24    In 1901...northwest winds were sustained to 50 mph with
        gusts as high as 57 mph in the city.
      In 1932...thunderstorm rainfall of only 0.11 inch was the
        only measurable precipitation for the month that year
        in the city.
      In 1986...a very strong wind storm roared across metro
        Denver.  Boulder was hit hardest.  Winds peaked to 131 mph
        at the National Center for Atmospheric Research.  This is
        thought to be the highest wind gust ever recorded in Boulder
        during September.  A wind gust to 118 mph was clocked on
        Davidson Mesa and to 92 mph near Niwot.  Gusts of 70 to 80
        mph were common over all of Boulder where an estimated 70
        to 90 large trees were uprooted.  About a dozen of them hit
        cars.  Two walls of a building under construction were
        toppled and solar panels were blown off a house.  Traffic
        lights and power lines were downed.  Damage to power
        equipment alone was estimated at 100 thousand dollars.
        Wind gusts to 87 mph at Jefferson County Airport damaged
        two planes.  A woman was seriously injured in Boulder.
        She suffered a fractured skull when struck by a falling
        tree limb.  Trees were also downed in Louisville and
        Lafayette.  West wind gusts to 45 mph were recorded at
        Stapleton International Airport.
25    In 1873...a fire was sighted in the woods near Platte Canyon...
        probably caused by high winds blowing sparks among the
      In apparent cold front produced northeast sustained
        winds to 40 mph with gusts to 48 mph.
      In 1910...a thunderstorm produced sustained north winds to
        51 mph.  This was the highest recorded wind speed in the
        city in September at the time.
      In 1936...a vigorous cold front produced a deadly dust storm
        in the city.  North winds sustained to 36 mph with gusts
        to 38 mph produced much blowing dense dust...greatly
        restricting the visibility.  The temperature plunged from
        a high of 84 degrees to a low of 38 degrees by midnight.
        The weather observer described the event with the following.
        "At 6:00 PM the temperature was 82 degrees and the wind
        velocity was only 4 mph; but with the wind shifting to the
        north and the barometer rising quite rapidly...the temperature
        fell sharply.  By 6:30 PM...the wind velocity increased
        rapidly and by 7:00 PM had reached a maximum sustained
        velocity of 36 mph...bringing with it clouds of dust which
        had been picked up by gale force winds in southern Wyoming
        and northern Colorado...covering the city.  The visibility
        was generally reduced to about 1/4 mile; however...the
        whirling of the dust down the streets and alleys...the
        visibility was at times somewhat less.  Airplanes were
        grounded...traffic was halted at times...and homes filled
        with dust.  The strong winds damaged electric power and
        telephone lines...leaving homes in darkness for a few hours
        in the city and for 18 hours in suburban towns and putting
        2500 telephones out of service because of broken lines.  An
        electric lineman was killed while repairing damage by the
        high winds.  The dust storm was followed by rain that began
        falling at 10:55 PM...which turned to snow during the early
        morning hours of the 26th.  A major snow storm followed on
        the 27th through the 29th."
      In 1999...high winds developed in the foothills of Boulder
        County.  Winds gusted to 90 mph at Wondervu.
25-26 In 1908...apparent post-frontal rain changed to snow overnight
        and totaled 6.5 inches in downtown Denver.  This was the
        first snow of the season.  Precipitation totaled 0.76 inch.
        North winds were sustained to 39 mph on the 25th.
25-27 In early season snowstorm brought heavy snow
        to the Front Range eastern foothills.  Snowfall totals
        included:  8 to 12 inches around Conifer...7 inches on
        Floyd Hill...and 6 inches at both Bailey and Chief Hosa.
        Snowfall totaled only 4.7 inches at the site of the
        former Stapleton International Airport.  This was the
        first measurable snow of the season.  After the passage
        of a strong cold front...north winds gusted to 38 mph at
        Denver International Airport on the 25th.
26    In 1907...a late afternoon thunderstorm produced hail...0.23
        inch of precipitation...and north winds sustained to 24 mph.
      In 1927...snowfall of 1.7 inches...mixed at times with sleet...
        was the first measurable snowfall of the season.
      In 2012...a man was seriously injured when he was struck by
        lightning outside the Hebrew Educational Alliance as he
        and his family were getting in their car. The victim
        stopped breathing but was saved when his wife performed
        cardiopulmonary resuscitation on him immediately
        following the lightning strike. He suffered burns to 15
        percent of his body which included his legs...chest...
        abdomen and neck. Lightning also caused 48 outages in
        Denver which affected 6582 Xcel Energy customers.
26-28 In 1936...the heaviest snowfall ever recorded in September
        and the heaviest snowfall ever recorded so early in the
        season dumped a total of 16.5 inches of snow on downtown
        Denver and 21.3 inches at Denver Municipal Airport.  The
        15.0 inches of snow measured from 6:00 PM on the 27th to
        6:00 PM on the 28th is the greatest 24 hour snowfall ever
        recorded in September.  This was the first snow of the
        season.  The snow was intermittent through the 26th...but
        continuous from early afternoon on the 27th to around
        midnight on the 28th...except for a period of rain during
        the afternoon of the 28th which contributed to a loss of
        depth on the ground.  The greatest snow depth on the ground
        downtown was 13 inches with 8 inches at Denver Municipal
        Airport.  There were no high winds with the storm and
        traffic was interrupted for only a short period.  The
        storm produced property damage estimated at 7 million
        dollars.  With trees and shrubs in full foliage...the leaves
        caught and held the heavy water-laden snow...until the
        branches snapped from the weight.  More than 3000 workmen
        were called to remove the debris and snow from the city.  The
        city firemen who were off well as all the reserves...
        were asked to report to their stations.  All schools in the
        city remained open...but attendance was only 50 percent of
        normal.  Grade school students were sent home at noon on the
        28th.  The early storm caught stockmen with many cattle still
        in higher ranges.  Warm weather followed the snow...which had
        all melted by the end of the month...except for a few inches
        in sheltered places.
27    In 1877...smoke from heavy forest fires in the mountains
        spread over the city on upper wind currents.
      In 1935...the first snow of the season was 2.8 inches in
        downtown Denver.  The low temperature dipped to 31
        degrees for the first freeze of the season.
27-28 In 1984...heavy snow fell over the plains and foothills.
        Snowfall amounts ranged from 2 to 5 inches on the plains
        with up to a foot at higher elevations in the foothills.
        The main problem caused by the storm was thousands of
        power outages caused by snow-laden tree limbs snapping and
        falling onto power lines.  Over 15 thousand homes lost
        power in metro Denver.  Some cars were damaged by falling
        trees and limbs.  The snow also caused some flight delays
        at Stapleton International Airport where 5.1 inches of
        snow fell and northeast winds gusted to 29 mph.  Maximum
        snow depth on the ground was 3 inches due to melting.  The
        high temperature of only 34 degrees on the 28th was a
        record low maximum for the date and equaled the all-time
        record for the month at that time.
28    In 1877...heavy dense smoke from mountain forest fires spread
        over the city.  The smoke was so dense that it obscured the
        sun at times.
      In northeast winds were sustained to 44
      In 1953...a Pacific cold front produced a west wind gust to 59
        mph at Stapleton Airport where the visibility was briefly
        reduced to 3/4 miles in blowing dust.  Strong winds were
        also widespread over Boulder during the afternoon.
      In 1960...strong...gusty winds tore the roof from 6 units of a
        motel on west Colfax Avenue in Denver.  The roofing sailed
        over the building and crashed down on a truck...wrecking it.
        The strong winds were the result of an apparent microburst.
      In 1999...snow fell in the foothills west of metro Denver and
        over the plains.  Snowfall totals included 7 inches at
        Conifer.  At the site of the former Stapleton International
        Airport...3.1 inches of snow were measured.  This was the
        first snow of the season.  The heavy wet snow snapped
        branches from fully leafed trees...downing power lines and
        causing scattered outages.
      In 2004...severe thunderstorms produced hail to 3/4 inch in
        diameter in Littleton and in Douglas County 14 miles
        northwest of Castle Rock.
      In 2012...a weak tornado (EF-0) tornado touched down near
        Strasburg.  No damage was reported.
28-29 In of the heaviest September snow storms of record
        began as rain and changed to heavy wet snow.  The storm
        caused heavy damage to trees and shrubbery...which were
        still in full leaf.  The storm dumped 10.6 inches of snow
        at Stapleton Airport...the third heaviest September snow
        amount to date.  Falling trees and limbs disrupted
        traffic...broke power and communication lines...and damaged
        buildings and cars.  One man was killed in Denver by a
        falling tree limb...and four others died of heart
        attacks while shoveling snow or trying to move heavy
        tree limbs.  Direct costs of the storm for cleaning up
        debris...repairing utility lines...and damage to buildings
        and other property across all of eastern Colorado were
        estimated to be over a half million dollars.  The value
        of trees destroyed or damaged was estimated to exceed
        five million dollars.  North-northeast winds gusted to
        32 mph at Stapleton Airport on the 28th.
      In unusually cold air mass for this time of year
        settled over the area.  Metro Denver received 8 to 12
        inches of powdery snow.  The 8.7 inches of snow that
        fell at Stapleton International Airport was the first
        measurable snow of the season and the city`s heaviest
        September snowfall since 1971.  The snow caused flight
        delays of over 2 hours at Stapleton International Airport.
        I-70 was closed for a time west of Denver.  Snow-laden
        tree limbs snapped over all of metro Denver...causing
        widespread power outages.  Ten thousand people were without
        electricity for a time in Boulder.  The morning of the 29th
        saw mid-winter temperatures along the Front Range.  The
        temperature dipped to 17 degrees...the lowest temperature
        ever recorded in September in Denver.  The high temperature
        of only 29 degrees on the 29th was a new record low maximum
        for the date and lowest ever recorded during the month of
        September.  The low temperature of 21 degrees on the evening
        of the 28th set a new record low for the date.  The cold
        weather persisted through the 1st with record minimum
        temperatures of 25 degrees set on the 30th and 27 degrees
        set on October 1st.
29    In 1966...a vigorous cold front moved thru metro Denver.
        North winds gusting to 51 mph kicked up billows of blowing
        dust...which briefly reduced the visibility to 1 mile at
        Stapleton International Airport.  The cold air caused
        temperatures to drop rapidly from a high of 86 degrees to
        a low of 46 degrees by days end.
      In 1985...the lowest temperature ever recorded in September...
        17 degrees...occurred.  The high temperature warmed to only
        29 degrees...the all-time record low maximum for the month.
      In 1994...the temperature reached a high of 91 degrees at
        Stapleton International Airport.  This was the 60th day
        of the year that the temperature had reached 90 degrees
        or more...establishing a new record at that time.  The
        previous record of 52 "90 degree days" occurred in 1978.
        Only 43 "90 degree days" were recorded at Denver
        International Airport during 1994.
      In 1995...lightning struck a couple in Aurora as they were
        walking in the rain.  The bolt struck the umbrella the man
        was carrying...injuring both the man and his wife.
      In 2000...late afternoon thunderstorms produced strong wind
        gusts to 76 mph in 69 mph near Boulder...and
        to 60 mph at Jefferson County Airport near Broomfield.  No
        damage was reported.
      In 2014...a storm system that moved through the area produced
        large hail and street flooding in parts of metro Denver and
        then spread east into the plains. The storm also caused
        multiple accidents. A semi became detached from a trailer...
        blocking traffic on westbound Interstate 70 west of Tower
        Road. Downed power poles blocked a roadway on CO 79 near mile marker 10. In addition to the damaging
        winds...the storms produced large hail...from nickel to
        golfball size across southern and eastern portions of
        metro Denver. The hailstorm was the most damaging of
        the 2014 summer season...with insured losses that topped
        213 million dollars.  Insurance claims included 29297
        automobile claims worth more than 87.2 million dollars and
        14287 property claims for 126 million dollars...ranking
        the storm as the eighth most expensive to hit the state. At
        Denver International Airport...1.01 inches of rainfall was
        recorded which was the greatest 24-hr rainfall for the date.
        In addition...a peak wind gust to 38 mph was observed at the
30    In 1898...south winds were sustained to 41 mph with gusts to
        54 mph.
      In 1940...a late season thunderstorm in the city caused one
        lightning death.
      In 1944...the month ended with a trace of rain on this date
        and for the month.  A trace of rain also occurred on the
        4th...9th...and 10th.  There was no measurable precipitation
        for the month.  The total of a trace of precipitation for
        the month equaled the driest September on record first set
        in 1892.
      In 2009...a trained spotter in Coal Creek Canyon...recorded a
        peak wind gust to 88 mph.
30-1  In 1959...heavy snowfall totaled 5.9 inches at Stapleton
        Airport.  Winds were light.

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