486
NOUS45 KBOU 120859
PNSBOU
COZ030>051-122300-
PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
259 AM MDT FRI SEP 12 2025
..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.
11-12 IN 1974...POST-FRONTAL RAIN CHANGED TO SNOW OVERNIGHT FOR THE
FIRST SNOW OF THE SEASON. SNOWFALL TOTALED ONLY 1.8 INCHES
AT STAPLETON INTERNATIONAL AIRPORT WHERE NORTH WINDS GUSTED
TO 40 MPH ON THE 11TH. HIGH TEMPERATURE OF ONLY 46 DEGREES
ON THE 12TH SET A NEW RECORD LOW MAXIMUM FOR THE DATE.
12 IN 1887...WEST WINDS TO 42 MPH WERE RECORDED IN THE CITY.
IN 1952...A THUNDERSTORM OUTFLOW PRODUCED STRONG SOUTHEAST
WINDS GUSTING TO 52 MPH. SURFACE VISIBILITY AT STAPLETON
AIRPORT WAS BRIEFLY REDUCED TO 2 MILES IN BLOWING DUST.
IN 1963...A NEARLY STATIONARY...WHITE TORNADO NEAR BENNETT WAS
SIGHTED FROM DENVER. NO DAMAGE WAS REPORTED.
IN 1989...AN EARLY SNOWFALL AND THE FIRST OF THE SEASON
BROUGHT 2 TO 3 INCHES OF SLUSH TO METRO DENVER. MORE SNOW
WHITENED THE FOOTHILLS WEST OF DENVER WHERE 6 INCHES WERE
MEASURED AT EVERGREEN. THE SNOW FELL ON LEAF LADEN TREES...
AND SAGGING BRANCHES ONTO POWER LINES CAUSED OUTAGES. MUCH
OF DENVER'S SNOW FELL DURING THE EVENING RUSH HOUR...CREATING
TRAFFIC CHAOS. SNOWFALL TOTALED 2.3 INCHES AT STAPLETON
INTERNATIONAL AIRPORT WHERE THE MAXIMUM SNOW DEPTH ON THE
GROUND WAS ONLY 1 INCH DUE TO MELTING.
IN 1994...THUNDERSTORM MICROBURST WINDS GUSTED TO 67 MPH IN
BOULDER. NO DAMAGE WAS REPORTED.
IN 2002...A SEVERE THUNDERSTORM PRODUCED HAIL AS LARGE AS
1 INCH IN DIAMETER NEAR CASTLE ROCK.
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