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Public Information Statement
National Weather Service Denver/Boulder CO
259 AM MDT FRI SEP 13 2024

...Today in metro Denver weather history...

1-30  In 2020...a worsening drought that started in the spring and
        continued through September. Outside of an early season
        snow on the 8th...the month of September was another
        unseasonably warm and dry period. The combination
        of hot...mostly dry conditions...and critically dry fuels...
        resulted in a continuation and rapid expansion of several
        massive wildfires. The Cameron Peak fire...which became the
        largest in the state`s history started on August 13th...and
        continued through September. As a result...very poor air
        quality continued to impact Denver and the entire Front
        Range.  Denver recorded the most days ever with a high
        temperature of 90 degrees or better; 75 days.  The last
        of which was 91 degrees on the 24th.  The previous
        record was 73 days set in 2012.
5-13  In 2010...the Fourmile Canyon Wildfire...northwest of Boulder...
        broke out on the morning of the 5th.  It originated from
        an unattended fire pit at a local residence. The wildfire
        quickly consumed 5 1/2 square miles or 3500 acres the
        first day...and forced the evacuation of over three
        thousand residents.  Erratic 45-mph gusts sent the fire in
        two directions at times. Very dry weather conditions
        preceded the fire. The combination of strong winds...low
        relative humidities and dry fuels allowed the wildfire
        spread rapidly through the steep...heavily forested terrain.
        The flames were reportedly 20 to 50 feet in length.  Towns
        within the burn area included Salina...Wallstreet and Gold
        Hill. The dry conditions coupled with gusty winds ranging
        from 45 to 64 mph persisted for several more days. Fire
        managers used as many as 700 firefighters and support
        personnel from 35 agencies and seven air tankers to battle
        the wildfire.  A total of 6181 square acres or
        approximately 10 square miles were burned.  The Fourmile
        Canyon Wildfire was the most destructive fire in Colorado
        history in terms of the damage to personal property.  It
        destroyed 171 homes with an estimated cost of 217 million
        dollars.
10-17 In 2018...the high temperature equalled or exceeded 90 degrees for
        8 consecutive days; breaking the previous streak of 7 consecutive
        days in the month of September.
10-18 In 2018...the high temperature equalled or exceeded 90 degrees for 9
        consecutive days; marking the first time such an occurrence has
        taken place in the month of September.  It also brought September
        of 2018 into a 4-way tie for most 90 degree + days in the month.
        Previous years included 2017...2005 and 1895. During the streak...4
        record high temperatures were either tied or broken...and one
        record high minumum temperatures was broken.
11-16 In 2013...a deep southerly flow over Colorado...ahead of a
        nearly stationary low pressure system over the Great Basin...
        pumped copious amounts of monsoonal moisture into the area.
        In addition...a weak stationary front stretched along the
        Front Range Foothills and Palmer Divide.  This resulted in
        a prolonged period of moderate to heavy rain across the
        Front Range Foothills...Palmer Divide...Urban Corridor. By
        the 14th...storm totals ranged from 6 to 18 inches...highest
        in the foothills of Boulder County. The headwaters then
        moved down the South Platte River and caused widespread
        flooding with record flood stages at several locations as
        it made its way downstream.  The record high flood stages
        resulted in widespread flooding along the South
        Platte River Basin. The flood damage encompassed 4500
        square miles of the Front Range...left 7 dead...forced
        thousands to evacuate...and destroyed thousands of homes
        and farms. Record amounts of rainfall generated flash
        floods that tore up roads and lines of communication...
        leaving many stranded. Nearly 19000 homes were damaged...
        and over 1500 destroyed. Colorado Department of
        Transportation estimated at least 30 state highway bridges
        were destroyed and an additional 20 seriously damaged.
        Preliminary assessments of the state`s infrastructure
        showed damage of $40 million to roads and $112 million to
        bridges. Repair costs for state and and county roads ran
        into the hundreds of millions of dollars. Miles of freight
        and passenger rail lines were washed out or submerged...
        including a section servicing Amtrak`s iconic California
        Zephyr. The town of Lyons was isolated by the flooding
        of St. Vrain Creek...and several earth dams along the
        Front Range burst or were over-topped. Floodwaters swept
        through Estes Park; damaged hundreds of buildings and
        destroyed large sections of U.S. 34 from Loveland and U.S.
        36 from Lyons to Boulder. U.S. 34 suffered the most damage...
        with 85 percent of its roadway and bridges destroyed. In
        Weld County...about nearly two thousand gas wells were
        damaged and had to be closed off as the floodwaters
        inundated entire communities. Sewage treatment plants and
        other utilities were knocked out in a number of towns.
        Governor Hickenlooper declared a disaster emergency on
        September 13th...in 11 counties across northeast Colorado
        including:  Adams...Arapahoe...Broomfield...Boulder...Denver...
        Jefferson...Larimer...Logan...Morgan...Washington and Weld. By
        the 15th...federal emergency declarations covered those
        counties as well as Clear Creek County. Projected losses
        from the flooding statewide was nearly two billion dollars
        in property damage...according to Eqecat...a catastrophe
        modeling firm.  The damage was most severe in and around
        Lyons and Boulder.  More than 11 thousand people were
        evacuated...reportedly the largest since Hurricane
        Katrina. President Obama declared a state of emergency
        for Boulder and Larimer Counties.  An additional 10
        counties were added on the 16th and included: Adams...
        Arapahoe...Broomfield...Clear Creek...Denver...Jefferson...
        Morgan...Logan...Washington and Weld Counties. The
        president also declared a major disaster specifically
        for Boulder County.  There were six fatalities
        directly attributed to flash flooding. Two 19-yr old
        teenagers died on the 11th...after they were swept
        away by floodwaters after abandoning their car on
        Lindon Drive in Boulder. In Jamestown...a 72-yr old
        man was killed when the building he was in collapsed.
        An 80-yr old Lyons resident died in the early morning
        hours of the 12th...when his truck was swept into the
        St. Vrain River near his home. Later on the 12th...a
        79-yr old Larimer County resident was killed when she
        was swept away while trying to climb to safety from
        her home in Cedar Point. A 61-yr old Cedar Point
        resident died when her home was swept down the Big
        Thompson River by the floodwaters. An 80-yr old
        Idaho Springs resident drowned in Clear Creek when
        the embankment he was standing on collapsed. In
        Boulder...some of the monthly records broken included:
        one-day all-time record: 9.08 inches which shattered
        the previous wettest day of 4.8 inches set on July 31...
        1919; one-month record of 18.16 inches...which broke
        the previous all-time monthly record of 9.59 inches set
        in May of 1995; wettest September on record which broke
        the previous record of 5.5 inches set in September of
        1940; one-year record of 34.15 inches broke the previous
        wettest year of 29.93 inches set in 1995. At Denver
        International Airport...the total precipitation for the
        month of September was 5.61 inches...which was 4.65
        inches above the normal of 0.96 inches. This is the most
        precipitation ever recorded in Denver for the month of
        September. Daily precipitation records included 1.11
        inches on the 12th and 2.01 inches on the 14th.
13    In 1899...west winds were sustained to 43 mph with gusts to
        46 mph.
      In 1928...northwest winds were sustained to 41 mph with gusts
        to 45 mph.
      In 1937...an apparent dry microburst produced brief north winds
        sustained to 31 mph with gusts to 41 mph.  There was a trace
        of rain.
      In 1982...torrential rains drenched both the foothills and
        plains from Denver north.  While the heaviest rain occurred
        north of Denver...just east of Denver 2 1/3 inches of rain
        fell in 5 hours along with hail that caused minor damage to
        a few airplanes.  Thunderstorm rainfall totaled 0.83 inch
        at Stapleton International Airport.
      In 1993...an upper level system combined with a cold and moist
        upslope flow to bring the heaviest snowfall to metro Denver
        for so early in the season.  Snowfall from the storm totaled
        5.4 inches at Stapleton International Airport; however...most
        of the snow melted as it fell leaving a maximum of one inch
        on the ground at any one time.  North winds gusted to 21 mph
        at Stapleton International Airport where a record low
        temperature of 33 degrees for the date was observed.
      In 2002...Friday the 13th proved to be bad luck for several
        motorists when heavy thunderstorm rainfall caused flooding
        on I-25 in central Denver.  Water rose several feet under
        the Logan Street overpass...inundating several vehicles.
        Some motorists were rescued...while others simply waited atop
        their cars for the flood water to recede.  The highway had
        to be closed in both directions for about 3 hours.  The
        flooding was exacerbated by poor drainage due to the
        construction along the highway.  A 12-foot drainage pipe
        had not yet been installed beneath the underpass.  The
        deluge also flooded several businesses along Broadway.
      In 2009...a severe thunderstorm produced large hail...up to
        half dollar size in the foothills of Jefferson County...
        west of Denver.

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