Historical High-Impact Weather and Climate Events
in Colorado, Wyoming, and Utah, 1862–2015

v. 5 - Revised 25 July 2016

- Overview of this Database

- Summary graphics for the Database

To Sort or Filter events: The default display of the events is sorted by state (CO, then UT, then WY), but is only partially sorted by year. Please click the gray double-arrow tabs to sort events by state, year, month, event type, deaths, or damage, and/or select from the dropdown menus to filter events by state, year, month, or event type.

We welcome your feedback on this resource so that we can make it more useful:

1) Can you identify any high-impact events that are missing from the database?
2) Are there events on the database that seem too minor compared with the others, and should be removed?
3) Are there additional sources or references you know of, for any of the listed events, that would provide more detail on this event?
4) Do you have other suggestions on the format/presentation/features that would make the database more useful?

Please send your responses to the WWA "Extremes Team" at wwa@colorado.edu.

State County City Year Month Day Event Type Deaths Unadjusted Damage CPI-Adjusted Damage (mid-2016) Summary Sources
CO Denver Denver 1864 5 19 Flood 19 $100,000 $1,468,280 Heavy rainfall on Plum Creek headwaters caused severe flooding on Plum Creek, Cherry Creek, and the South Platte River. Urban Drainage and Flood Control District: Flood History

NCAR: Most Damaging Floods in CO

Library of Congress Photos
Denver Library Photos

USGS: Floods in Colorado (1948) see p. 12
CO Garfield, Mesa, Grand, Eagle, Larimer Grand Junction, Glenwood Springs, Fort Collins 1884 6 Flood Extreme snowmelt flooding on the Colorado River. Estimated peak discharge of ~210,000 cfs downstream at Lees Ferry, AZ, the largest flood in the historical record (since ~1850). Peak discharges upstream in western Colorado likewise believed to be the largest on in the historical. Severe flooding on the Cache la Poudre River on the eastern slope. Urban Drainage and Flood Control District: Flood History

USGS: Floods in Colorado (1948) see p. 14-15
CO Boulder Boulder, Jamestown, Lyons, Longmont 1894 5 31-June 2 Flood 3 $350,000 $9,472,474 Severe flooding from multi-day rain event on Boulder Creek, James Creek, Lefthand Creek, and St. Vrain Creek. Estimated flow of 9,000-13,000 cfs on Boulder Creek at Boulder is consistent with the 100-year flood (11,000 cfs). Over 8" of rain in Boulder. Urban Drainage and Flood Control District: Flood History

NCAR: Most Damaging Floods in CO

USGS: Floods in Colorado (1948) see p. 15-16.

BCN Basin: Photos
CO Jefferson Evergreen, Morrison, Golden 1896 7 24 Flood 29 $250,000 $6,843,012 Thunderstorm-driven flash flooding in tributaries of Bear Creek (Tucker Gulch, Mt. Vernon Creek, Turkey Creek) and in Clear Creek. Peak discharge in Bear Creek was 8,600 cfs. Urban Drainage and Flood Control District: Flood History

NCAR: Most Damaging Floods in CO

Chicago Tribune

LA Herald


Morrison Historical Society
CO Pueblo Pueblo, Eden 1904 8 7 Flood 111 Flash flood in Dry Creek near Eden swept away a passenger train crossing trestle, causing the heavy fatalities. Additional flooding on Fountain Creek Urban Drainage and Flood Control District: Flood History

Wikipedia article

USGS: Report on floods of 1921 see pp. 40-41
CO Las Animas Trinidad, Tabasco, Berwind 1905 8 25 Flood 35 $100,000 $2,618,088 Flash flood in Rhode Canyon and Berwind Canyon damaged houses, railroads, and mines; the high-water mark was 30 feet above normal flow in Rhode Canyon. Urban Drainage and Flood Control District: Flood History

NWS Monthly Weather Review
CO La Plata, San Miguel, Huerfano, Rio Grande, Alamosa Durango, Telluride, Del Norte, Monte Vista, Walsenburg 1911 10 5 Flood 3 $1,000,000 $24,331,054 Heavy rain events across southern Colorado caused severe flooding on the Animas River, Rio Grande, San Miguel River, and Huerfano River. Fatalities occurred in the Walsenburg area. The Animas River at Durango experienced its all-time record peak discharge, at 25,000 cfs. Urban Drainage and Flood Control District: Flood History

NCAR: Most Damaging Floods in CO

USGS: Floods in Colorado (1948) See p. 17-18

Monthly Weather Review

Durango Herald
CO Denver, Douglas Denver, Franktown, Parker 1912 7 14 Flood 2 $2,000,000 $47,698,420 Centered over Sullivan, a cloudburst caused flooding on Cherry Creek and surrounding drainages. A wall of water 30 feet high rolled down Cherry Creek, shattering the retaining walls on the creek. Affecting Denver, Franktown, and Parker, the water was 3 feet high in some places. Two lives were lost. Urban Drainage and Flood Control District: Flood History

Monthly Weather Review see p. 917-918

CO Emergency Management

Illinois Popular Press
CO Larimer, Denver, Boulder, Clear Creek, Jefferson many 1913 12 2-6 Winter Storm Huge upslope snow event impacted much of Front Range; 46" storm total for Denver is still the all-time record-largest snowstorm, 86" in Georgetown. Denver was brought to a standstill. Colorado Weather Almanac by Mike Nelson

NOAA Event Poster

Denver Post story
CO Boulder, Larimer, Clear Creek, Grand 1921 4 14-15 Winter Storm Upslope snowstorm is still the U.S. record for 24-hour snowfall, with 76" recorded at Silver Lake northwest of Nederland in 24 hours and a storm total of 95". Over 60" fell in northwestern Larimer County, 52" in Georgetown, and 48" in Estes Park and Grand Lake. Colorado Weather Almanac by Mike Nelson

Climatological Data for April 1921

Article on the record at Silver Lake
CO Pueblo, Denver, Boulder Pueblo, Denver, Broomfield 1921 6 2-7 Flood 78 $81,449,000 $1,096,046,204 Over 9" of rain fell in the Pueblo area, causing extreme flash flooding on the Arkansas River. A bridge collapse in Pueblo caused many fatalities. Related rain events caused flooding and damage on the South Platte River, Coal Creek, Boulder Creek, and St. Vrain Creek. Urban Drainage and Flood Control District: Flood History

NCAR: Most Damaging Floods in CO

USGS Event Report

Monthly Weather Review

USGS: Floods in Colorado (1948) see pp. 19-22

Biennial report of the State Engineer of Colorado see p. 32
CO La Plata, Rio Grande, Alamosa Durango, Del Norte, Monte Vista, Alamosa 1927 6 29 Flood 3 Heavy rains in the San Juans flooded the San Juan Basin and the Rio Grande River. Bridges and train tracks washed out. Urban Drainage and Flood Control District: Flood History
CO Jefferson Idledale, Morrison 1933 7 7 Flood 7 A flash flood in Mt. Vernon Canyon, tributary of Bear Creek killed 7 people. The flood crest was 15 feet high. Urban Drainage and Flood Control District: Flood History

Monthly Weather Review

Denver Post
CO Denver Denver 1933 8 3 Flood 2 $1,000,000 $18,529,280 A convective rain event (3"-9") near Castle Rock led to the failure of Castlewood Dam, causing severe flooding and destruction on Cherry Creek 40 miles downstream into downtown Denver. Urban Drainage and Flood Control District: Flood History

Urbana (IL) Daily Courier article

Research Paper: Geomorphologic Impacts of the Castlewood Dam failure
CO Jefferson Kittredge, Morrison, Idledale 1934 8 9 Flood 6 $50,000 $898,546 A convective rain event near Kittredge caused severe flooding in Mount Vernon Canyon and Bear Creek; many motorists were caught and 6 were killed. Urban Drainage and Flood Control District: Flood History
CO Statewise   1934 Drought 1934 was the worst year of the Dust Bowl drought (1931-1939) in Colorado. Statewide precipitation was only 69% of average, still the 4th lowest on record. The Palmer Drought Severity index for summer 1934 was -5.9, the record worst until 2002. 1934 was the warmest calendar year statewide until it was finally exceeded by 2012. Streamflows were extremely low throughout Colorado. Agricultural impacts were enormous, after three previous years of drought.

NCDC Warmest Calendar Years

CSU: A History of Drought in Colorado

NOAA NCEI: Climate at a Glance

 

CO El Paso, Elbert, Weld Colorado Springs, Kiowa, Fort Morgan 1935 5 30-31 Flood 27 $5,528,000 $97,194,966 Multiple convective rain events over a two-day period caused severe to extreme flooding on Monument Creek, Kiowa Creek, and the South Platte River. Urban Drainage and Flood Control District: Flood History

NCAR: Most Damaging Floods in CO

Biennial report of the State Engineer of Colorado 1935-1936
CO Boulder, Jefferson Boulder, Eldorado Springs, Longmont, Morrison 1938 9 1-3 Flood 6 $450,000 $7,687,790 Multi-day rain event, similar to September 2013, caused flooding on South Boulder Creek, Big Thompson River, Coal Creek, St. Vrain Creek, Cache la Poudre River, and Bear Creek. Highest rainfall totals were 8"-10" near Fort Collins. Morrison suffered extensive damage, to the point that relocating the downtown was considered. Event is still the flood of record on South Boulder Creek at Eldorado Springs (7,300 cfs). Urban Drainage and Flood Control District: Flood History

Colorado Climate Center Historic Floods

Biennial report of the State Engineer of Colorado 1937-1938 see pp. 347-361
CO Denver, Douglas, Arapahoe Denver, Castle Rock 1946 11 2-6 Winter Storm 13 Upslope snow event with strong northerly winds left 30" in Denver, and up to 50" on the plains east of Denver. Colorado Weather Almanac by Mike Nelson

Chicago Tribune story
CO many 1951 2 1-2 Cold Wave

An Arctic air mass brought extremely cold temperatures to the Front Range and across Colorado; all-time record lows of -25 F in Denver, -41 F in Fort Collins, and -60 F at Taylor Park Reservoir. Many fruit orchards on the Front Range were destroyed, prompting a major shift of fruit-growing to Colorado's Western Slope.

Colorado Weather Almanac by Mike Nelson

Description of the event in Ohio see p. 101

Colorado Climate magazine see p. 4
CO Larimer, Boulder, Denver Loveland, Fort Collins, Lyons, Denver 1951 8 2-3 Flood 4 $500,000 $4,632,320 Multiple convective rain events caused severe flooding on Big Thompson River, Poudre River, Boulder Creek, St. Vrain Creek and the South Platte River. Flood damage was experienced in Fort Collins, Loveland, Lyons, and Denver. A dam failed on Buckhorn Creek west of Fort Collins. Urban Drainage and Flood Control District: Flood History

USGS: Floods of 1951 see pp. 281-282
CO many many 1951 12 29-31 Winter Storm The "Snow Blitz": a very strong jet stream combined with a possible Atmospheric River event brought huge snow totals to the high mountains, and 36" at Dillon. Colorado Weather Almanac by Mike Nelson

Colorado Climate magazine see p. 4
CO Las Animas Trinidad, La Junta, Las Animas 1955 5 18-20 Flood 1 $4,310,000 $38,737,776 Heavy rain event (6"-10" SW of Pueblo) caused severe flooding on the Purgatoire River, Raton Creek, and Arkansas River. The high-water mark on the Purgatoire River was 30 feet above normal. Urban Drainage and Flood Control District: Flood History

NCAR: Most Damaging Floods in CO

Colorado Climate Center Historic Floods

USGS: Floods of 1955see p. 93-95
CO Denver Denver, Englewood 1956 7 29- August 2 Flood 0 $5,000,000 $44,278,982 Convective precipitation led to severe flooding on the South Platte River. Urban Drainage and Flood Control District: Flood History
CO Adams, Arapahoe, Bent, Douglas, Denver, Elbert, El Paso, Larimer, Pueblo, Morgan, Otero, Prowers, Sedgwick, Weld Denver, Castle Rock, Englewood, Fort Morgan, Sterling, Julesburg, Colorado Springs, Pueblo, Fort Collins, Loveland 1965 6 16-18 Flood 21 $540,000,000 $4,129,329,666 By some measures, this is still the most costly and destructive flood event in Colorado history. Intense thunderstorms near Castle Rock dropped over 14" of rain in several hours, causing extreme flooding on Plum Creek, Cherry Creek and the South Platte River. The flood zone included two-thirds of Denver's industrial area. The Purgatoire River and lower Arkansas River also experienced severe flooding; 11" of rain fell at Holly and over 15" near Lamar in one day. Urban Drainage and Flood Control District: Flood History

NCAR: Most Damaging Floods in CO

Colorado Climate Center Historic Floods

U.S. Army Corps of Engineers: Event Report

USGS: Event Report
CO Boulder Boulder 1969 1 7-8 High Wind 2 $1,000,000 $6,563,832 Frequent gusts of over 100 mph in west Boulder; roofs blown off or other severe damage to 25 houses in Boulder. Two fatalities in wind-related vehicular accidents. Weather Extremes of the West by Tye Parzybok

Climatological Study of Strong Downslope Winds in the Boulder Area Information on the 1969 event can be found throughout, see p. 93 for observations
CO Boulder, Jefferson Jamestown, Boulder, Eldorado Springs, Morrison 1969 5 4-8 Flood 1 $4,569,000 $29,988,068 Multi-day rain event with totals of 6-14" over much of Boulder and Jefferson Counties caused severe flooding on Left Hand Creek, Boulder Creek, South Boulder Creek, Bear Creek, and Turkey Creek. Some of the precipitation in the upper portions of the drianages fell as snow, otherwise the flooding would have been even worse. The flood on South Boulder Creek was a 25-year event. Urban Drainage and Flood Control District: Flood History

NCAR: Most Damaging Floods in CO

Colorado Climate Center Historic Floods

CO San Juan Silverton 1970 9 6 Flood 0 $3,081,000 $19,126,932 A widespread rain event associated with Tropical Storm Norma dropped 4-6" near Durango and Pagosa Springs and caused widespread flooding in the San Juans, including the Animas River. Urban Drainage and Flood Control District: Flood History

NCAR: Most Damaging Floods in CO

Colorado Climate Center Historic Floods

USGS Flood Report see p. 32-38
CO Jefferson, Denver, Arapahoe, Kiowa Golden, Denver, Englewood 1973 5 6-7 Flood 2 $120,000,000 $651,020,876 Heavy rain and snowmelt caused severe flooding on Bear Creek, Turkey Creek, Plum Creek, and the South Platte River. The worst flooding in Denver since the June 1965 flood. Stapleton Airport measured 3.27" of precipitation in 24 hours. Urban Drainage and Flood Control District: Flood History

US Army Corps of Engineers report
CO Larimer Drake, Loveland, Fort Collins 1976 7 31 Flood 144 $35,500,000 $150,283,628 A massive, near-stationary thunderstorm dropped up to 12" of rain in 6 hours in Big Thompson Canyon, causing extreme flash flooding. Hundreds of homes were destroyed along Highway 34, and many motorists were trapped. The estimated discharge of 33,000 cfs at the canyon mouth was estimated to be a 300-year event. The most deadly natural disaster in Colorado history. Urban Drainage and Flood Control District: Flood History

NCAR: Most Damaging Floods in CO

USGS Event Report

USGS: The Big Thompson Flood 30 years Later see references for additional sources
CO Statewide 1977   Drought 1977 was the driest water year on record for the Western Slope, at 62% of average precipitation, and saw the lowest water-year streamflows on the upper Colorado River. The lack of snow seriously impacted the ski industry and spurred widespread adoption of snowmaking.

CSU: A History of Drought in Colorado

NOAA NCEI: Climate at a Glance

CO Adams, Arapahoe, Denver, Weld Thornton 1981 6 3 Tornado 0 $50,000,000 $132,495,726 An F2 tornado tore a swath through the heart of Thornton, destroying 87 homes and damaging 600 others. The same thunderstorm complex also spawned tornadoes in Lakewood and Fort Lupton, damaging several dozen other homes, and caused damaging hail and non-tornadic winds. Research Paper: Subsynoptic Analysis of the Denver Tornadoes of 3 June 1981

Northglenn-Thornton Sentinel article
CO Boulder Boulder 1982 1 16-17 High Wind 0 $17,000,000 $42,434,326 Winds gusted over 100 mph in Boulder and 137 mph at NCAR Mesa Lab. Forty percent of the buildings in Boulder sustained damage. Weather Extremes of the West by Tye Parzybok

NOAA News article

New York Times article
CO Boulder, Denver, Douglas, Arapahoe Boulder, Denver metro area 1982 12 23-24 Winter Storm $7,400,000 $18,471,376 An upslope event accompanied by strong winds brought blizzard conditions to the Denver metro area and adjacent eastern plains. Storm totals were 24" in Boulder, 25" in Denver, up to 34" in the western suburbs, and 48" in the foothills. Colorado Weather Almanac by Mike Nelson

Event profile in Weatherwise (paywall)

Denver Post blog post
CO Statewide 1983 6 Flood 10 $15,392,000 $37,225,034 A very large winter snowpack caused extensive and sustained flooding during spring runoff. NCAR: Most Damaging Floods in CO

Research Paper: Analysis of 1983 snowmelt runoff production in the upper Colorado River Basin

Hydrology analysis of the Colorado River floods of 1983 (paywall)
CO Statewide 1984 5 Flood 2 $28,990,000 $67,208,966 A very large winter snowpack caused extensive and sustained flooding during spring runoff. NCAR: Most Damaging Floods in CO

National Water Summary 1984 see pp. 42-43
CO Boulder, Jefferson Boulder, Lakewood, Golden 1987 1 28-29 High Wind 0 $5,600,000 $11,874,456 Widespread residential and infrastructure damage from gusts of 60-100 mph. Weather Extremes of the West by Tye Parzybok
CO Boulder 1989 7 9 Wildfire 0 $10,000,000 $19,425,758 The Black Tiger Fire in the Sugarloaf area west of Boulder destroyed 44 residences and burned 1778 acres. Nearly all of the damage occurred in the first several hours after ignition. National Fire Protection Association: Case study
CO Lincoln Limon 1990 6 6 Tornado 0 $12,000,000 $22,116,226 An F3 tornado destroyed 80% of the business district in Limon and damaged over 200 residences, causing 14 injuries. Weather Extremes of the West by Tye Parzybok

National Weather Digest: Event summary

Research Paper: Mesoscale aspects of the tornado
CO Larimer, Boulder, Jefferson, Denver, Arapaho, Douglas, El Paso Denver metro area, Colorado Springs 1990 7 11 Hail 0 $600,000,000 $1,105,788,552 A supercell thunderstorm traveled from Estes Park to Colorado Springs, passing directly over Denver with large hail. Thousands of roofs and cars were damaged. At the time, the costliest hailstorm in US history. Rocky Mountain Insurance Information Association

Colorado Weather Almanac by Mike Nelson

Los Angeles Times article
CO Garfield Glenwood Springs 1994 7 6 Wildfire 14 The South Canyon Fire had been burning for four days when a cold front with strong and erratic winds passed over the fire, causing a blowup that killed 14 wildland firefighters within an hour of the front's arrival. The front was well-forecast but the information was not communicated to the front lines.

USFS: Fire Behavior Associated with South Canyon Fire

South Canyon Fire - Official Accident Investigation Report

CO Larimer, Logan Fort Collins, Sterling 1997 7 27-29 Flood 5 $200,000,000 $300,158,826 Two consecutive days of heavy convective precipitation in and near Fort Collins; on the 28th, over 10" fell in 6 hours in the Spring Creek watershed on the west side of Fort Collins. The resulting flash flood on Spring Creek heavily damaged Colorado State University and residential areas, and caused 5 fatalities. The following day, 13" fell on Pawnee Creek near Sterling, causing damaging flash flooding there. Urban Drainage and Flood Control District: Flood History

NCAR: Most Damaging Floods in CO

Colorado Climate Center Historic Floods

CSU: Report on Flooding

CSU: Study of changes made in response to the flood
CO Routt Clark 1997 10 25 High Wind 0 A strong upslope snowstorm on the Front Range led to rare damaging easterly downslope winds west of the Continental Divide, in the Park Range in Routt County. Gusts of up to 120 mph blew down over 4 million trees over an area 30 miles long and 5 miles wide. Colorado Weather Almanac by Mike Nelson

National Weather Digest: Event Summary

High Country News article

Research paper: Forest Blowdown--Observations, Analysis, and Modeling
CO many many 1997 10 24-26 Winter Storm 9 24,000 head of cattle lost CIMSS (U. of Wisconsin) report: Synoptic-scale storm evolution

Research Paper: Kinematic Evolution of the Storm
CO El Paso, Pueblo, Otero Colorado Springs, Manitou Springs, Pueblo, La Junta 1999 4 29-3 Flood 0 $60,510,000 $87,487,774 Multi-day rain event caused severe flooding on Fountain Creek, Monument Creek, and the Arkansas River. Urban Drainage and Flood Control District: Flood History

NCAR: Most Damaging Floods in CO

Colorado Water Conservation Board: Colorado 1999 Flood Documentation Study
CO Teller, Jefferson 2002 6 8-2 Wildfire 1 $38,612,000 $51,700,000 The Hayman Fire burned 138,000 acres and over 200 residences, making it the largest wildfire in Colorado history, but it has been superseded as the most destructive wildfire. It ignited and spread during severe drought conditions, abetted by several periods of high winds. Rocky Mountain Insurance Information Association

USFS: Hayman Fire case study
CO Statewide Statewide 2002 10 Drought $1,200,000,000 $1,606,742,940 The worst year of a multi-year drought (2000-2002 for eastern Colorado, and 2000-2004 for western Colorado). One of the driest water years on record in all parts of the state, with very low snowpacks, extremely low runoff, many large wildfires, and severe agricultural impacts. The statewide summer Palmer Drought Index was -8.7, the lowest on record.

Report on the 2002 Drought

NOAA NCEI: Climate at a Glance

 

CO many Fort Collins, Boulder, Denver metro area 2003 3 17-20 Winter Storm $93,000,000 $121,748,330 A very strong three-day upslope snowstorm brought huge snow amounts and blizzard conditions to most of the Front Range and the adjacent plains. Storm totals included 32" in Denver, and 87" in Rollinsville. Rocky Mountain Insurance Information Association

CSU: Meteorological and climatological event analysis

Research paper: Dynamics and thermodynamics of the event
CO many 2006 12 27-30 Winter Storm An upslope snowstorm first dropped 20+" on the Denver Metro area, then the focus shifted east and south, with totals of 12-36" in southeastern Colorado and 30-48" in the foothills and mountains of southern Colorado. Strong winds created enormous drifts and led to enormous loss of livestock. Colorado Weather Almanac by Mike Nelson

Colorado Dept. of Emergency Mgmt.: Post- incident report on Front Range event

Colorado Dept. of Emergency Mgm.: Post- incident report on SE Colorado event.
CO Prowers, Kiowa Holly 2007 3 28 Tornado 2 $4,010,000 $4,659,204 An EF3 tornado cut from south to north through Holly and the surrounding area, damaging or destroying 160 homes. Two residents of Holly were killed.

Colorado Weather Almanac by Mike Nelson

Colorado tornado facts (Rocky Mountain PBS)

NOAA News article

Denver Post article

CO Larimer Windsor 2008 5 22 Tornado 1 $193,500,000 $216,484,444 An EF3 tornado destroyed 80 homes and damaged 770 others in and around Windsor, during a damaging hailstorm. Rocky Mountain Insurance Information Association
CO Arapahoe, Jefferson, Adams Englewood, Arvada, Wheat Ridge, Lakewood, Brighton 2009 7 20 Hail $770,000,000 $864,539,808 A line of severe thunderstorms with damaging winds dropped large hail over a swath of the Denver metro area and spawned two weak tornadoes. Rocky Mountain Insurance Information Association

Denver Post article

CO Boulder Salina, Gold Hill 2010 9 6-16 Wildfire 0 $214,352,000 $236,786,000 The Fourmile Canyon Fire started after a month of extremely dry conditions, on a day with unusually strong winds for early September. Most of the 169 homes destroyed were burned on the first day of spread. About 6,500 acres were burned, and the city of Boulder itself was at risk on September 10. Rocky Mountain Insurance Information Association

USFS: Fourmile Canyon Fire Findings

CSU research summary prepared for the Hayman Fire Science Symposium
CO Larimer Fort Collins 2012 6 9-30 Wildfire 1 $112,354,000 $117,876,000 The High Park fire was ignited by lightning after a very dry winter and spring, and burned over 87,000 acres and at least 259 homes. Rocky Mountain Insurance Information Association

Inciweb: Event summary
CO El Paso Woodland Park, Manitou Springs, Colorado Springs 2012 6 23-7/10 Wildfire 2 $446,460,000 $468,402,000 The Waldo Canyon Fire burned during severe to extreme drought conditions; strong outflow winds from a thunderstorm on June 26 pushed the fire into the western portion of Colorado Springs, where most of the 346 homes destroyed in the fire were lost. Two residents killed. Over 18,000 acres burned. The most costly wildfire in Colorado history. Rocky Mountain Insurance Information Association

Colorado Springs: After-action report
CO Douglas, Elbert, El Paso 2013 6 11-20 Wildfire 2 $293,000,000 $302,962,000 The Black Forest Fire ignited during moderate drought conditions, on a red-flag-warning day where temperatures were in the 90s F and relative humidity was below 10%. It rapidly spread through densely forested suburban neighborhoods, destroying 511 homes in all, and burning over 14,000 acres. The most destructive wildfire in Colorado history, in terms of homes lost. Rocky Mountain Insurance Information Association

Inciweb: Event summary

El Paso County: After-action report
CO Adams, Arapahoe, Bent, Douglas, Denver, El Paso, Gilpin, Jefferson, Larimer, Logan, Pueblo, Morgan, Weld Loveland, Lyons, Longmont, Jamestown, Boulder, Estes Park, Morrison, Evans, Colorado Springs 2013 9 12-18 Flood 10 $2,000,000,000 $2,068,000,000 A near-stationary weather system funneled copious subtropical moisture into the Front Range, leading to one-week rainfall totals of 10-18" over a large area. Creeks and rivers from the Wyoming border to Colorado Springs flooded, with the worst flooding on the Big Thompson River, Little Thompson River, St. Vrain Creek, Lefthand Creek, and Coal Creek. Over 20,000 homes were damaged or destroyed. Incredible and widespread damage to civil infrastructure (roads, bridges, water conveyance and treatment) on the Front Range. WWA & NOAA & CSU: Event Preliminary Assessment

Colorado Climate Center: Historic Floods

USGS: September 2013 Event Page

UCAR Perspective
CO Mesa 6 mi. SE of Collbran 2014 5 25 Landslide 3   The longest (2.8 miles) and largest mass-movement earth failure in Colorado history occurred 3 hours after a short, intense rainstorm, and two weeks after a late spring snowstorm. The fast-moving landslide dropped 2100 feet in elevation and covered almost a square mile of the West Salt Creek valley with 38 million cubic yards of debris. Three local men, who were investigating an earlier, much smaller, landslide, died during the catastrophic event. The toe of the landslide came within 200 feet of active gas-production wellheads. The loss of irrigation ditches and water impacted local ranches and residents.

Colorado Geological Survey and Colorado School of Mines: Report

Mesa County webpage on the event

UT Millard, Beaver 2007 7 5 Wildfire $4,000,000 $4,647,830 The Milford Flat Fire was the largest wildfire in Utah's history, burning 363,000 acres. The fire was ignited by dry thunderstorms and took place in cheatgrass, sagebrush, and pinyon-juniper stands. The fire destroyed rangeland in Millard and Beaver Counties killing cattle, burning four buildings and a cabin. Large stretches of I-15 were closed during the fire. Two people were killed in a fire-related motorcycle accident. FEMA Disaster Declaration

BLM: Milford Flat Fire Rehabilitation

Deseret News article
UT Sanpete Fountain Green 2012 6 23 Wildfire 1 $5,800,000 $6,085,090 The Wood Hollow fire was ignited when winds blew power lines together, sparking grass below (ground wires were removed by copper thieves). One person died in the fire and two fire fighters were injured. The fire burned 47,387 acres, destroyed 52 residential buildings, 108 non-residential buildings, damaged power and water infrastructure, and killed livestock including 300 sheep, and 15 horses. Suppression costs were estimated at $5.8 million. FEMA Disaster Declaration

Inciweb: Event summary
UT Millard Delta 2012 6 26 Wildfire $6,600,000 $6,924,698 The Clay Springs Fire was human-ignited and burned 107,846 acres. The fire forced the evacuation of nearly 1,000 people and damages included one cabin, minor damage to several residences, 3 city storage structures, and dozens of power poles damaged. Two firefighters were injured by the blaze. Surpression costs and property damages were estimated at $6.6 million. FEMA Disaster Declaration
UT Weber 2001 8 20 Landslide $1,000,000 $1,359,710 Reactivation of the prehistoric Heather Drive landslide forced several homeowners to evacuate. Three houses were moved off the slide path and three were demolished. According to the Utah Geological Survey, "Landslide reactivation was characterized by a gradual reactivation, followed by relatively rapid movement and an abrupt stop." Utah Department of Natural Resources: Technical Report
UT Duchesne Roosevelt 1993 8 11 Tornado 0 $50,000 $83,754 Thunderstorms produced a high elevation F3 tornado with hail and microburst winds. The tornado began in Ashley National Forest and moved from the southwest, touching down three times with a path of up to 1/2 mi. wide. One thousand acres of woodland were affected, with many trees uprooted and some up to 18 inches in diameter snapped. 125 scouts were camped near the third touchdown; no injuries were reported but falling trees damaged four vechicles. NOAA Storm Events Database

Deseret News article
UT Weber North Ogden 1996 5 29 Tornado 0 $600,000 $921,294 An F1 tornado touched down on the west side of Washington Boulevard and traveled north for approximately 1.25 miles. Numerous trees were downed, causing major damage to two homes. NOAA Storm Events Database

Deseret News article
UT Uintah Naples 1999 9 3 Tornado 0 $700,000 $1,012,286 An F1 tornado in the Naples area damaged or destroyed several mobile homes, garages, and sheds. Several houes were damaged by flying debris. Power poles were pulled out of the ground and numerous trees were downed, with some thrown up to a quarter of a mile away. Agriculture damage included hay pastures and gardens.

NOAA Storm Events Database

NOAA NWS report

UT Salt Lake Salt Lake City 1999 8 11 Tornado 1 $230,000,000 $332,543,706 During the early afternoon, the most destructive tornado in Utah's history touched down in southwest Salt Lake City. Shortly after touching down the tornado intensified to an F2. It moved northeast, causing widespread damage at Delta Center including the only fatality of the storm at an outdoor retailers' convention tent. The tornado skirted the Capitol Building and ripped out several large trees there and in Memory Grove. Before lifting off, it caused significant damage in the residential area known as The Avenues. The storm resulted in 1 fatality, 80 injuries, 300 buldings and homes damaged, with 34 deemed uninhabitable. The event destroyed 500 trees and damaged 300 more. Additional damages were inflicted on vehicles and infastracture. The storm had an average width of 300 to 600 ft., a path length of 4.5 mi., and was on the ground for 14 minutes. NOAA Storm Events Database

Regional NWS report

Deseret News article

University of Utah summary and links
UT Sanpete Manti 2002 9 8 Tornado 0 $2,100,000 $2,811,446 An F2 tornado touched down one mile south-southwest of Manti. The tornado moved northeast through Manti, causing significant damage to residential and commercial areas. The storm threw a 40-foot semi trailer loaded with insulation approximately 40 ft. In a residential area, it threw a 26-foot camp trailer between 150 and 200 ft. Winds reached 157 mph, and the path was 2.75 miles long and 800 feet wide. The tornado was on the ground for 15 minutes. No injuries were reported. NOAA Storm Events Database

Deseret News article
UT Statewide 1983 6 Flood 7 $300,000,000 $725,535,052 Record snowpack resulted in severe flooding from extensive runoff. Flooding occurred all along the Wasatch Front, damaging homes and public property. Creeks and rivers across the state saw record flows, including five of the six creeks in Salt Lake Valley. In June, high waters caused the failure of a dam near Delta, the resulting flood destroyed the town of Deseret. Seven people died in the floodwaters. Utah's Top 10 Weather Events of 1900s

NRC Report: Utah landslides, debris flows, and floods, May and June 1983
UT Utah, Davis, Salt Lake, Weber, Cache 1983 4 4 High Wind $10,000,000 $24,195,600 60-80 mph winds along the Wasatch Front from Utah County northward caused damage to private property and infrastructure. The peak gust of 104 mph was recorded in Hill Field/Layton. Winds damaged or destroyed 54 major transmission towers from the Ben Lomond Substation. Extensive glass damage was reported in Ogden, and 12 flatbed railroad cars were overturned near Farmington. Utah's Top 10 Weather Events of 1900s
UT Statewide 1990 12 18-21 Winter Storm 1 $5,000,000 $9,215,008 A cold winter storm produced snow across all of Utah, ranging from 0.5" at Lake Powell to 33" in mountainous areas. More than 40 stations established or tied record daily minimum temperatures. Seven people were killed in a weather-related accident involving a Greyhound bus. Utah Hazard Mitigation Plan

NOAA climatological data see p. 40-41
UT Davis, Juab, Salt Lake, Tooele, Utah, Weber 1993 1 6 Winter Storm 1 $5,000,000 $8,335,074 Heavy snow fell almost continuously for 6 days. Salt Lake City airport recorded 23.3", establishing a new single storm record. Utah Hazard Mitigation Plan
UT Statewide 1996 10 24 Winter Storm 0 $1,000,000 $1,535,490 Winter storm Utah Hazard Mitigation Plan
UT Statewide 1997 1 11 Winter Storm 3 $40,000,000 $60,031,972 Blizzard Utah Hazard Mitigation Plan
UT Statewide 1997 3 31 Winter Storm 3 $2,000,000 $3,001,702 Winter storm Utah Hazard Mitigation Plan
UT Statewide 2003 12 25 Winter Storm 0 $1,500,000 $1,963,566 Winter storm Utah Hazard Mitigation Plan

Deseret News article
UT Statewide 1934 Drought   The worst year of the Dust Bowl drought (1931-36) in Utah. In 1934 there was only 50% of mean annual streamflow across the state. The statewide summer Palmer Drought Index was -6.4, stil the lowest on record.

USGS: Major floods and droughts in Utah

NOAA NCEI: Climate at a Glance

UT San Juan, Kane, Garfield, Wayne, Grand   1884 7 Flood Estimated to be a 500-year event with an estimated peak discharge of 300,000 cfs at Black Canyon of the Colorado River. Newspaper stories indicate that the event was caused by an unusually high snow pack and the late arrival of spring. USGS: Major floods and droughts in Utah

Deseret News article

Bureau of Reclamation: Report on probable maximum floods, Colorado River
UT Davis, Box Elder Ogden, Salt Lake 1923 8 13 Flood 7 $3,000,000 $42,259,580 Several cloudbursts in Davis and Box Elder counties caused locally intense flooding. Damage was exacerbated by mudflows attributed to overgrazing in the waterhseds. Observers reported flood crest 75-100 ft. high and 200 ft. wide in Farmington Canyon. Flood waters destroyed four dwellings near Willard and killed two women in their house. USGS: Major floods and droughts in Utah

USGS Cloudburst Floods in Utah 1850-1983

The Floods of 1923 in Northern Utah
UT Carbon, Emery, Utah, Salt Lake, Davis, Cache, Wayne, Rich, Weber 1952 4 28 Flood 2 $8,400,000 $76,353,662 A record snowpack in April combined with a sudden rise in temperatures produced widespread flooding throughout the state. USGS: Major floods and droughts in Utah

Conference abstract: Upstream aspects of the flood.
UT Uintah 1965 6 10 Flood 7 $814,000 $6,224,680 Flood was caused by heavy rainfall on an above-average snowpack. Most of the flooding came from the area above 9,200 ft. During the event the snowline moved from 9,200 ft to 9,900 ft. The flood waters damaged bridges, canals, roads, fences and farm land. Seven campers in Sheep Creek were swept away. USGS: Major floods and droughts in Utah

USGS: Floods of 1965 see p. 53
UT Washington 1966 12 6 Flood 0 $1,400,000 $10,408,244 A widespread, slow-moving storm brought highly variable rain to southern Utah. Precipitation ranged from 1" to greater than 12". This storm was unprecedented in its areal coverage. In some areas, snowfall also contributed to the flooding. Floods caused damage to roads, croplands, bridges and other infrastructure, including campgrounds and an amphitheatre at Zion National Park. USGS: Major floods and droughts in Utah

USGS event report

USGS: Floods of 1966 see p. 69
UT Uintah, Carbon, Emery, Wayne, Sevier, Summit, Kane, Garfield, Piute, Millard, Juab, Beaver, Delta, Salt Lake, Utah, Davis 1984 4 17 Flood 1 $47,000,000 $108,962,920 The flooding of 1984 was very similar to the flooding in 1983. On April 1st, the Wasatch had above-average snowpack and the sudden onset of warm temperatures produced floods. The lower monetary damages compared to 1983 have been partially attributed to flood mitigation measures taken after 1983. Above-average precipitation since 1982 brought Great Salt Lake levels to a 101-year record high. USGS: Major floods and droughts in Utah

Chicago Tribune article
UT Salt Lake, Davis, Weber, Box Elder, Tooele 1986 6 3 Flood 0 $268,000,000 $589,006,726 Continued greater-than-average precipitation brought the Great Salt Lake to a 140-year record-high elevation of 4,211.85' and caused widespread flooding. USGS: Major floods and droughts in Utah
UT Uintah, Carbon, Emery, Wayne, Sevier, Summit, Kane, Garfield, Piute, Millard, Juab, Beaver, Delta, Salt Lake, Utah, Davis 1983 4 10 Landslide 0 $200,000,000 $483,689,690 On April 10, a landslide caused by heavy precipitation dammed the Spanish Fork River, which then inundated the community of Thistle. The slide also destroyed the Rio Grande railroad tracks and US 6 and US 89. The landslide was the most costly geological event in Utah's history. Presidential Disaster declaration.

USGS: Major floods and droughts in Utah

NRC Report: Utah landslides, debris flows, and floods, May and June 1983

Research paper: 1983 Thistle landslide (paywall)

UT Weber 1930 7 17 Landslide $350,000 $5,047,988 Heavy rain from a cloudburst caused landslides which buried 600' of railway tracks with 40' of debris. Additionally, the debris flow blocked four miles of highway. Utah Geologic Society Landslide Database

NOAA Monthly Weather Review
UT Sevier Monroe 1943 7 31 Landslide $200,000 $2,784,562 A landslide surrounded several homes with mud, and cut off electricity and water for two weeks. The mud, rock and debris from the slide covered 115 acres of cropland. Utah Geologic Society Landslide Database
UT Davis, Salt Lake, Weber Centerville, Salt Lake City 2011 12 1 High Wind $68,000,000 A downslope windstorm along the Wasatch Front with winds of 60-80 mph. The peak gust of 102 mph recorded in Centerville. The majority of damage occured between North Salt Lake and South Ogden. Winds caused $4 million in infrastructure damage, almost entirely in Davis County, destroying hundreds of trees, powerlines, street signs and light poles. Private insured losses in Davis County alone were estimated at $64 million, mostly damage to glass, roofs, and fences. Additionally, 11 semi-trailers were knocked over on I-15. Damages resulted from wind directly and also from flying debris.

Utah Hazard Mitigation Plan

Research paper: Analysis of the downslope windstorm 1 December 2011

Deseret News article

 

UT Washington 1862 1 18 Flood Rain-on-snow event; primary accounts describe the flood as a wall of water 10-15' high, carrying trees and logs. The flood destroyed Fort Clara, the grist mill, schoolhouse, and 7 houses. The event also killed livestock and destroyed much of the orchards and fields. Utah Historical Society article
UT Utah, Cache, Davis, Box Elder 1988 8 26 Hail $310,000 $630,740 Severe thunderstorm caused flooding, lightning damage, hail, high winds, and mudslides. Heavy rain caused 9 mudslides in American Fork Canyon, and basement flooding in Davis County. Lightning struck a house in Holladay, causing a fire. Widespread damage was reported to roofs, power poles, and trees. Utah Hazard Mitigation Plan
UT Salt Lake 1994 10 5 Hail $1,550,000 $2,518,824 Hail from two severe thunderstorms caused significant roof damage. The first storm moved northward through the Salt Lake Valley, producing hail between 0.75" and 1" in diamater and damaging the roof of the McDonnell-Douglas plant. The second storm moved north along the Wasatch Front and produced hail measuring 1" in diameter. This storm caused significant damage to the roof of the Cottonwood Heights Mall, 12 miles south of Salt Lake City. Utah Hazard Mitigation Plan
UT Kane, Washington 2005 1 8-12 Flood 1 $225,000,000 $277,509,056 After six years of drought, the Virgin River basin experienced heavy rain in October 2004, resulting in minor flooding and saturating the soil heading into the winter. During January 8th - 12th a Pacific storm system produced between 0.7" and 7.7" of rain on soil that was highly saturated, resulting in significant flooding. Damages included 30 homes destroyed and 20 more siginficantly damaged. Utah Hazard Mitigation Plan

USGS Report on 2005 Utah water year

Oral histories collected at the time of the event by the Utah Historical Society

KSL.com news article
UT Statewide 1966 4 19-20 Cold Wave Subzero temperatures killed 70% of Utah's fruit crop. Mark Eubank's Utah Weather
UT Salt Lake, Davis, Weber Salt Lake City, Ogden 1930 7 10 Flood $500,000 $7,212,150 Severe cloudburst occuring in the same general area as the 1923 floods caused several canyon flood events. Destructive mudflows accompanied the floods, covering many acres with alluvial debris, including boulders estimated to weigh up to 300 tons. Mark Eubank's Utah Weather

USGS: Cloudburst Floods in Utah 1850-1983

USDA Report: Floods and Accelerated Erosion in N. Utah

Torrential Floods in N. Utah 1930
UT Salt Lake Salt Lake City, Bountiful, Bingham 1951 7 27 Flood $500,000 $4,632,320 Severe thunderstorm caused significant flooding in Salt Lake City. Sections of the highway between Bingham and Copperton were completely destroyed.  
UT Washington, Iron, Garfield, Kane, San Juan 1970 9 5 Flood 2 $700,000 $4,345,902 A mass of moist tropical air from Pacific Tropical Storm Norma collided with a cold front, producing heavy rains throughout Utah, Colorado and Arizona. The majority of the damage was in Arizona where the event killed 23 people. In Utah, the storm killed a couple who were swept away in their car. The flooding also caused infrastructure damage. Mark Eubank's Utah Weather

USGS: Floods of September 1970 in Arizona, Utah, Colorado and New Mexico

NWS: Report on Arizona impacts
UT Salt Lake, Weber, Davis, Box Elder, Cache, Morgan Salt Lake City, Brigham, Centerville, Farmington, Kaysville 1959 10 29 High Wind $5,000,000 $41,387,918 Winds over 100 mph caused damage to roofs, windows and vehicles, and overturned 11 semi-trailers. Mark Eubank's Utah Weather
UT Salt Lake, Davis, Weber 1970 5 23 High Wind $1,500,000 $9,312,204 100 mph winds and 0.75" hail damaged 125 houses, 3 single-engine airplanes, and high-voltage towers and lines, and caused 35 injuries. Mark Eubank's Utah Weather

Deseret News article on historic wind events in SLC
UT Juab, Weber, Salt Lake, Utah, Davis, Morgan, Box Elder, Cache, Summit 1977 3 27 High Wind 100 mph winds caused extensive damage to homes. Mark Eubank's Utah Weather

Deseret News article on historic wind events in SLC
UT Statewide 1966 9 16 Winter Storm $1,000,000 $7,434,460 Early-season snowstorm destroyed crops across Utah. Additional damage was done to power lines, trees, and shrubs. Mark Eubank's Utah Weather
UT Weber, Box Elder 1977 3 21-22 Winter Storm $1,000,000 $3,974,696 15" of snow knocked down power and telephone lines for 20 miles and caused widespread damage to livestock and buildings. Mark Eubank's Utah Weather
UT Statewide 1977 Drought $41,000,000 $173,567,240 Drought forced 36% of municipal water suppliers to raise water rates in an effort to increase conservation. In 1977, crop losses in hardest-hit areas ranged from 40-100%. The 1976-77 winter snowpack was limited, causing economic hardship for the ski industry. The statewide summer Palmer Drought Index was -5.3, the 3rd lowest on record.

USGS: Major floods and droughts in Utah

NOAA NCEI: Climate at a Glance

UT Statewide 1990 Drought The worst year of a statewide drought from 1987-1992 that seriously impacted agriculture. The statewide summer Palmer Drought Index was -5.2, the 4th lowest on record.

USGS: Major floods and droughts in Utah

NOAA NCEI: Climate at a Glance

UT Statewide 2002 Drought $320,000,000 $462,669,504 The worst year of a statewide drought from 2000-2004. One of the worst droughts on record in the Upper Colorado River Basin. Low precipitation combined with above-average temperatures reduced available water. The statewide summer Palmer Drought Index was -6.1, the 2nd lowest on record. Dryland farmers reported low yields and a state of agricultural disaster was declared for drought and then grasshopper and Mormon cricket infestations. Costs are from 2002 and 2003 combined.

USGS: Major floods and droughts in Utah

NOAA NCEI: Climate at a Glance

UT Washington Hildale 2015 9 14 Flood 21 $1,250,000 $1,292,500 Moisture from the remnants of Hurricane Linda spread into the Southwest and intersected with a strong upper-level trough, sparking isolated heavy thunderstorms. Two successive storms passed over Hildale between 2:00 pm and 5:00 pm, dropping an estimated 2" in rain. This caused two flood peaks on Short Creek in Hildale, the second of which swept away two vehicles with 16 people inside, 13 of whom drowned. The second storm also produced heavy rain in Zion National Park, about 15 miles north of Hildale, causing a flash flood in Keyhole Canyon that killed seven park visitors who were canyoneering. Another motorist 15 miles west of Hildale was swept away and killed by flooding the same day.

NOAA Storm Events Database (Hildale fatalities)

NOAA Storm Events Database (Zion fatalities)

Weather.com article

Washington Post article

Wasatch Weather Weenies (Jim Steenburgh, U. of Utah): blog post

 

WY Bighorn 1876 8 Wildfire Lakota Sioux people are said to have set the Bighorn Fire while retreating from General Crook's troops. It is estimated that the fire burned 500,000 acres. A first-hand account says that on August 3, "a terrible red glow" lit up the midnight sky," and looking westward, they saw "the whole front of the Big Horn mountains on fire."

Wyoming Hazard Mitigation Plan

First-hand account of the fire

WY Laramie 1904 5 20 Flood 2 Heavy rains resulted in flooding, with a 20-25' wall of water observed on Crow Creek. The flood damaged buildings, transportation facilities, utilities, bridges and houses. A large number of people were trapped in their homes. WRDS Flood History

USGS Report on 1904 Floods in the Denver District see pp. 154-158
WY Johnson 1912 6 11 Flood Heavy rain, possibly associated with a thunderstorm, coupled with heavy snowmelt runoff caused flooding. WRDS Flood History

USGS National Water Summary see p. 577
WY Hot Springs 1917 6 19 Flood Cool weather preserved an above-average snowpack in the mountains until hot June weather quickly melted the snow, resulting in floods. The flood washed out bridges, destroyed irrigation flumes, and flooded low-lying ground. The return period was estimated at 100 years. WRDS Flood History

Monthly Weather Review see p. 510
WY Hot Springs, Fremont 1923 7 24 Flood 2 $1,000,000 $14,086,182 A cloudburst produced 4.1" of rain, which fell on an above-average spring snowpack, resulting in widespread flooding. Damage was reported to infrastructure, including the Chicago and Northwestern Railways, private property and farm equipment, crops and livestock. Hot Springs residents were left without water or electricity. WRDS Flood History

USGS Contributions to the Hydrology of the United States see pp. 108-114
WY Johnson, Sheridan, Natrona 1923 9 26 Flood 18 $100,000 $1,408,308 After five days of consistent rain caused high-flow conditions, a cloudburst occured on the Powder River, resulting in a large flood. Observers reported a 20' to 30' high wall of water, which inundated farms and ranches, killing 4,500 sheep. Eighteen people were killed when a train crashed due to a weak bridge at Cole Creek south of Casper. Peak discharge on the Powder River was approximately 100,000 cfs. WRDS Flood History

USGS Contributions to the Hydrology of the United States see pp. 114-117
WY Teton Jackson 1925 6 23 Landslide 6 $500,000 $6,882,304 A block slide/rock slide/rock fragment/flow complex dammed the Gros Ventre River. Two years later, on May 18, 1927, the dam failed, flooding Kelly, Wyoming and causing 6 fatalities. Wyoming Hazard Mitigation Plan

Wyoming Geological Ass'n: Report (paywall)

US Forest Service: Brief History of the Gros Ventre Slide

WY Big Horn 1929 3 9 Flood $220,000 $3,098,898 An ice jam on a shallow stretch of Eight Mile Gorge caused the Big Horn River to overflow its banks. The flooding covered streets with up to 4' of water, damaging 412 homes and 93 other buildings. The flood impacted 295 families, the Midwest Oil Company, and the livestock industry. In addition to residential damage, the Burlington railroad tracks were washed out and there was a loss of livestock including horses, sheeps, hogs, and poultry. WRDS Flood History

Greybull Standard article on historic floods
WY Laramie 1929 6 1 Flood 1 $500,000 $7,043,608 Rainfall combined with snowmelt runoff and ground saturation resulted in significant flooding on Crow Creek. The flooding damaged bridges, dams, highways, crops, and railroads. One person died when they did not hear warnings to evacuate. According to a FEMA Flood Insurance Study, the flood was a 500-year flood and the Creek had a discharge of 8,000 cfs. WRDS Flood History
WY Platte 1935 5 31 Flood 8 $1,250,000 $21,977,670 Heavy rain produced a flood on Rock Creek near Wheatland that killed 8 people and damaged property, roads, and railroads. Discharge of streams was 14,000 cfs. Same weather pattern led to extreme precipitation and flooding in eastern Colorado.

WRDS Flood History

NY Times article (paywall)

WY Park 1937 8 21 Wildfire 15 The Blackwater Fire was the most deadly in Wyoming history. During efforts to combat the blaze, winds caused the fire to rapidly shift direction, overrunning fire lines, killing 15 firefighters and injuring 38 others. Death in the Blackwater

USFS: Factors and circumstances that led to Blackwater Fire tragedy
WY Bighorn 1937 7 1 Landslide Landslides and flooding damaged highways and railroads in 12 counties, with severe damage in the upper Big Horn Basin. Over 3,000' of railway was washed out. Wyoming Hazard Mitigation Plan
WY Laramie, Albany, Platte, Goshen, Converse, Niobrara 1949 1 2 Winter Storm 17 $9,000,000 $91,088,162 A blizzard produced over 30" of snow with drifts 20-30' high. Storms shut down 3300 miles of state highway, stranding motorists. After the initial storm, blizzards continued until February 2nd, causing cities to run out of food. 15% (55,000) of the state's cattle and more than 105,000 sheep died. Wyoming Hazard Mitigation Plan

Wyoming Tribune Eagle article
WY Weston W of Newcastle 1953 5 28 Tornado $50,000 $450,824 A tornado on the evening of the 28th cut a swath, averaging about 0.25-mile in width, from six miles west of Newcastle to the northeast ending near the county line. Farm buildings in the path were damaged or destroyed, with the loss estimated at $50,000. Wyoming Hazard Mitigation Plan
WY Platte, Natrona, Goshen, Converse 1955 6 26 Flood A series of convective events including heavy precipitation, hail, and a tornado caused widespread damage. 6" to 8" of rain fell in the North Platte Valley, overflowing the Interstate Canal and inundating Ft. Laramie with 5' of water. Torrington experienced 2" of rain along with baseball-sized hail, which severely damaged crops in the valley. A tornado southwest of Torrington uprooted trees and destroyed two farmhouses. WRDS Flood History

USGS: 1955 Flood Summary of the US see pp. 99-105
WY Platte Chugwater 1955 6 27 Tornado $210,000 $1,887,050 An F3 tornado, about 14 miles south-southeast of Wheatland and 10 miles north of Chugwater, injured three persons and destroyed their farm home. Loss from demolished ranch buildings was estimated at $10,000. Another tornado southwest of Wheatland caused approximately $200,000 of damage. Wyoming Hazard Mitigation Plan

WY Laramie 19 mi. W of Cheyenne 1960 4 23 Tornado $25,000 $203,698 At 7:30 p.m. an F3 tornado moved through a ranch 19 miles west of Cheyenne. The tornado destroyed several buildings and killed or injured cattle. In crossing the highway a few minutes later the tornado caught an auto-transport truck and turned it over several times, seriously injuring the driver. The storm then continued toward the north-northwest for an unknown distance.

Wyoming Hazard Mitigation Plan

Research blog

WY Fremont, Park, Sheridan, Big Horn, Washakie, Hot Springs Lander 1963 6 15 Flood $90,000 $708,290 Above-average late-season snowpack combined with hot weather and and heavy rain caused widespread flooding. Flood waters damaged infrastructure and private property, and resulted in crop and livestock losses. One person died in Sheridan. The failure of an earthen dam in Lander resulted in damage to homes and inundated part of the town. WRDS Flood History
WY Natrona, Converse, Albany, Platte 1965 5 14 Flood $175,000 $1,337,996 A rain-on-snow event caused flooding of streams flowing out of the Laramie Mountains below Wheatland and Casper. Flood waters damaged homes, utilities, and park facilities and disrupted water and sewer services. Many bridges and culverts were also destroyed. WRDS Flood History

USGS: Flood summary of the US 1965 see pp. 40-43

USGS: Report with WY State Engineer's Office (library only)
WY Statewide 1965 9 17 Winter Storm $2,750,000 $21,029,492 An early cold snap along with 18-22" of snow caused significant damage to crops, trees, power lines, and phone lines. Snow fell in a band from the southwest part of the state to the northeast part. The event caused a 5% loss of marketable livestock statewide. Wyoming Hazard Mitigation Plan

Chicago Tribune Article
WY Crook 15 mi WNW Pine Bluffs 1965 7 12 Tornado $250,000 $1,911,866 An F3 tornado touched down, and damaged crops and Air Force sites. Wyoming Hazard Mitigation Plan
WY Natrona 1967 7 15 Flood $1,000,000 $7,212,150 Over 2" of rain in less than 2 hours caused flash flooding in Casper, damaging residential property. WRDS Flood History

Flood summary of the US 1967 see pp. 42-47
WY Crook, Campbell, Weston, Sheridan, Johnson, Converse, Niobrara 1969 4 27 Winter Storm $5,500,000 $36,099,008 A late snowstorm during shearing and lambing caused heavy sheep loss. Wyoming Hazard Mitigation Plan
WY Converse 1970 6 12 Flood $1,000,000 $6,208,136 Flood waters damaged the Northeast residential area of Glenrock, including a municipal park, a trailer court, croplands, bridges, fences and farm buildings. WRDS Flood History
WY Fremont 1974 3 2 Flood $500,000 $2,443,342 A combination of abnormally high temperatures, rain, and strong chinook-type winds in late February and early March resulted in rapid snowmelt and flooding along the Popo Agie River. In the southern portion of Hudson, an ice jam against a highway bridge intensified the flooding and forced nearly 60 families from their homes. WRDS Flood History
WY Park, Big Horn 1975 7 5 Flood Thunderstorms and cloudburst dumped locally torrential rains over the Absaroka Range, swelling the North and South Forks of the Shoshone River. The flood damaged lodges and ranches in the area. Hail, heavy rains, and wind caused scattered crop losses along the east slopes of the Absarokas. A hailstorm and windstorm struck the Cowley-Lovell area, causing heavy crop losses. Farmers in the Heart Mountain area reported a 20 percent loss to some of their crops. WRDS Flood History
WY Statewide 1975 3 28 Cold Wave $2,750,000 $12,312,872 Zero-degree weather along with 40-50 mph winds caused considerable losses of newborn calves and cows. Wyoming Hazard Mitigation Plan
WY Crook, Campbell Gillette, Sundance 1975 6 25 Tornado An F3 tornado first touched down at a trailer park just northeast of Gillette around 2:30 p.m., destroying 5 of 8 mobile homes and injuring one person. Straight-line winds, clocked at 75 mph at the Campbell County Airport, caused scattered damage to outbuildings and trees from Rozet eastward to Wyodak. Most of the damage was attributable to straight-line winds. Wyoming Hazard Mitigation Plan
WY Park, Big Horn, Sheridan, Campbell, Crook, Weston, Johnson, Washakie, Hot Springs, Natrona, Converse, Niobrara 1978 5 15 Flood $15,500,000 $57,263,954 Heavy wet snow and record rains did very extensive damage to property, crops, and livestock in 12 counties. Hundreds of homes were damaged, and many totally destroyed. Numerous bridges and sections of roads were washed out, power lines downed, with much damage to cars and personal property. WRDS Flood History

USGS and NOAA: Event Report
WY Big Horn, Campbell, Converse, Crook, Johnson, Natrona, Sheridan, Washakie, Weston, Hot Springs, and Niobrara 1978 5 7 Winter Storm $11,753,000 $43,420,762 A spring snow storm produced 15-32" of wet heavy snow and caused extensive damage to crops and livestock. I-80 west of Cheyenne was closed for almost two days. Wyoming Hazard Mitigation Plan

WY Statewide 1979 1 31 Winter Storm $2,500,000 $8,294,748 Heavy snow combined with extreme cold caused considerable livestock losses. Wyoming Hazard Mitigation Plan
WY Laramie Cheyenne 1979 7 16 Tornado 1 $30,000,000 $99,535,942 The most damaging tornado in the history of Wyoming rapidly developed from a moderate thunderstorm and moved through the north portion of Cheyenne housing and airport areas. Damage included four C-130 aircraft and National Guard ground equipment, City-owned airport hangars and building damaged, 40 homes destroyed, 100 homes with major damage, 225 homes with lesser damage, and 17 trailer homes destroyed. One of the trailer homes was sheltering a family when it was struck, killing a 14-month old boy and severely injuring the mother and a second child. Wyoming Hazard Mitigation Plan

Research blog
WY Yellowstone National Park, Park, Hot Springs, Fremont, Big Horn, Sheridan, Johnson, Natrona 1982 9 14 Winter Storm $2,750,000 $6,864,726 An early-season snowstorm produced up to 17" of snow, resulting in considerable loss to property and crops. Wyoming Hazard Mitigation Plan
WY Statewide 1983 12 25 Cold Wave $2,750,000 $6,650,688 Arctic outbreak caused lows between -20 and -40 F. The majority of damage was caused by freezing water pipes. Wyoming Hazard Mitigation Plan

WY Carbon 1984 5 14 Flood $5,000,000 $11,592,174 High runoff from melting snow in the mountains of southern Wyoming and northern Colorado. Flooding in the Little Snake drainage burst a small dam, and a 4-foot wall of water poured down the canyon. $5 million of damage to area; damage to water treatment plant, land crops, fences, irrigation systems, structures, livestock, 26 homes and trailers. Runoff estimated at 500-year level. WRDS Flood History
WY Campbell, Sheridan, Bighorn, Park, Crook Wright, Sundance 1984 4 25 Winter Storm 2 $100,000,000 $231,836,242 2' to 3' of spring snow fell along with 65 mph winds, causing 15-20' drifts. Storm occurred during spring calving and lambing season, causing the loss of more than 200,000 sheep and cattle. High winds and the weight of snow on structures caused significant economic damage. Wyoming Hazard Mitigation Plan

Gillette News Record article

Chicago Tribune article
WY Goshen 1984 6 22 Tornado $2,500,000 $5,795,570 Wyoming Hazard Mitigation Plan
WY Laramie 1985 8 1 Flood 12 $65,000,000 $145,511,718 A near-stationary thunderstorm produced record flash floods in Cheyenne and across the state. The storm killed 12 people, injured 70, and caused extensive damage to private and public property. Damage estimates ranged from $40 to $65 million. The NWS Forecast Office near the airport reported 6.06" of rain in 3 hours. In addition to the rain, there was hail up to 2" in diameter and 70 mph winds. Ten of the 12 deaths occured along Dry Creek when people attempted to cross flooded streets in their cars.

WRDS Flood History

USGS webpage for the event

USGS: National Water Summary 1985 see pp. 41-42

WY 1985 9 27 Cold Wave $2,750,000 $6,156,436 Early snow (7"), and cold (0 degrees F) destroyed most of the potato crop in the eastern area of the counties. Wyoming Hazard Mitigation Plan
WY Natrona Casper 1986 9 2 Hail $29,000,000 $63,735,760 Hail up to 2" in diameter caused extensive damage to vehicles, buildings, and vegetation. Wyoming Climate Atlas

Wyoming Hazard Mitigation Plan
WY Laramie Cheyenne 1987 8 3 Hail $37,000,000 $78,454,750 Hail from 0.5" to 2" diameter caused considerable damage to three car dealerships west of downtown and to vehicles at Warren Air Force Base. Wyoming Climate Atlas

Wyoming Hazard Mitigation Plan
WY Teton   1987 7 21 Tornado $2,500,000 $5,301,318 A tornado cut across the Teton Wilderness, 45 miles northeast of Jackson. About 15,000 acres of trees were downed. This was the highest-elevation F4 tornado ever documented in the U.S. The downed trees were mostly mature lodgepole pines, from 80' to 100' tall. The massive blowdown stretched over 24 miles, from Box Creek Trailhead, 10 miles east-northeast of Moran Junction and was about one to two miles wide. The F4 rating was applied after inspection by Dr. Ted Fujita of F (Fujita)-scale fame. F4 winds may be needed to do F3 damage in the thinner air at this altitude (up to 10,000 feet). Not all experts agree that this entire event should be attributed to a tornado. Wyoming Hazard Mitigation Plan

Fujita (1989) research paper on the event
WY Park 1988 7 Wildfire In 1988, Yellowstone National Park recorded almost no rain during the summer months. During the later half of summer, several smaller fires were started by lightning. High winds and dry conditions caused the fires to rapidly spread and merge. Before a cold front helped contain the fires, 9,000 firefighters, and 100 engines were mobilized to fight the blazes. Before containment, the complex burned 793,880 acres (36% of the park) and cost $120,000,000 in supression efforts. The fire destroyed 67 buildings along with backcountry and frontcountry infrastructure. The fires had far-reaching ecological impacts which have been the subject of numerous studies.

NPS: Book chapter on the event

Schullery (1989) research paper

USFS Fire Growth Maps

WY Park, Big Horn, Washakie 1988 5 7 Flood $750,000 $1,527,218 The winter-like storm system of May 6-7 produced heavy snowfall above 6000' and drenching rainfall below. Between 1.5" and 5" of rain fell in less than 24 hours. Reported damage included beet and barley crops, along with public infrastructure. Most of the damage occured in Park County, where at least 17 bridges or crossings were destroyed, and six roads were washed away. WRDS Flood History
WY Sweetwater 1989 7 12 Flood $1,500,000 $2,913,812 A weak upper-level southerly flow, very moist tropical air and an upper-level disturbance caused a slow-moving torrential thunderstorm over Rock Springs. 18" of hail fell 5 miles south of Rock Springs, causing a flash flood/mud flow between 3' and 4' deep. Floodwaters resulted in damage to homes, businesses and cars. The conductor of a train died when the engine hit a stationary car that was moved onto the track. WRDS Flood History

NOAA Storm Data report
see p. 12
WY Teton Jackson 1997 5 18 Landslide A slump/debris flow complex covered 300' of the highway with debris 15' deep. Road was opened twice a day to commuter traffic in three weeks and to full-time traffic in six weeks. A Presidential Disaster was declared and the National Guard was mobilized to help clear the roadway. Known as the Wolf Mountain or Snake River Landslide. Wyoming Hazard Mitigation Plan

Transportation Researcj Board: Event summary

USGS: Event summary
WY Converse 2002 6 18 Wildfire The Hensel Fire was ignited by lightning near Laramie Peak. The fire burned 4 homes and 3 outbuildings and 14,380 acres. FEMA Disaster Declaration

Billings Gazette article
WY Johnson 2002 8 26 Flood $460,000 $616,264 A stationary thunderstorm brought flash flooding and an estimated 3" of rain to Kaycee. The flooding, with depths up to 4', did damage to 19 trailers and 22 houses, and 12 businesses. There were Doppler radar rainfall estimates of 7" to 7.5" along Murphy Creek in southern Johnson County. Also, rain gage measurements in excess of 4" were reported in this area. Most of the rain fell between midnight and 4 a.m. A damage survey conducted by the National Weather Service Riverton office determined that Murphy Creek was at one point 300 yards wide and 20' deep near Lone Bear Road. WRDS Flood History

NOAA: Event report
WY Laramie Cheyenne 2002 8 26 Hail $30,000,000 $40,168,832 Hail from 1" up to 2.75" in diameter fell over mainly the central and western parts of the city of Cheyenne. Significant damage was reported to automobiles and roofs. Wyoming Climate Atlas
WY Campbell, Crook Gillette 2003 6 21 Hail $17,000,000 $22,254,782 A strong upper-level shortwave produced a long-lived supercell thunderstorm. The storm produced several tornadoes which touched down with no damage. Golf-ball to baseball-sized hail was experienced across Campbell and Crook Counties, causing extensive damage to cars and roofs. NOAA Storm Events Database

Wyoming Hazard Mitigation Plan
WY Park 2004 7 18 Landslide A rockslide/debris flow closed the east entrance of Yellowstone on Highway 14/16/20, trapping three vehicles. The road was closed for one week. Wyoming Hazard Mitigation Plan

Billings Gazette article

WY Crook Carlile 2006 7 14 Wildfire The Thorn Divide Complex began as 26 lightning-ignited fires. Before firefighters contained the fire, 14,874 acres and 2 buildings were burned. Supression costs were estimated at $7 million. FEMA Disaster Declaration

Sundance Times article
WY Natrona 2006 8 14 Wildfire The Jackson Canyon Wildfire was ignited by a lightning strike near Coal Mountain in Jackson Canyon. The fire burned 11,256 acres of land, including seven cabins, one barn, and two outbuildings before it was contained on August 23. The estimated cost of suppression was $3.8 million. FEMA Disaster Declaration

NOAA Storm Events Database
WY Campbell Gillette 2010 5 26 Hail $46,000,000 $50,813,862 A severe thunderstorm produced hail up to around golf-ball size in Gillette, causing extensive damage across the city. The storm moved generally from south to north through the city. The most heavily damaged areas were in the Westover Hills and Foothills subdivisions, as well as the downtown area. The hail damaged the roofs and windows of several thousand homes and buildings. Thousands of automobiles were damaged across the city. Wyoming Climate Atlas
WY Laramie Cheyenne 2011 7 11 Hail $120,000,000 $128,502,418 The most costly hailstorm in Wyoming history. Hail up to 2" in diameter covered most of Cheyenne, with accompanying rain totalling 1.46" of precipitation. Widespread damage to buildings and cars.

Rocky Mountain Insurance Information Association

Wyoming Tribune-Eagle article

WY Teton Afton 2011 5 18 Landslide Slide blocked Highway 89, forcing Afton residents to detour 75 miles through Idaho to get to Jackson. Wyoming Hazard Mitigation Plan

AGU Blog

Pinedale Online article

Jackson Hole News & Guide article
WY Albany 2012 6 29 Wildfire The Arapahoe Fire was started by lightning on July 27th and burned 98,115 acres before it was contained on August 23rd. The fire destroyed 30 homes and damaged 8 others. Firefighters struggled to contain the fire during extremely dry conditions and erratic winds. FEMA Disaster Declaration

Inciweb Page

Billings Gazette article
WY Statewide   1934     Drought   The worst year of the Dust Bowl drought (1930-36, 1938-39) in Wyoming. The statewide summer Palmer Drought Index was -7.8, the 2nd-lowest on record.

Wyoming Climate Atlas

NOAA NCEI: Climate at a Glance

WY Statewide   1988     Drought   The worst year of a 4-year drought (1987-1990) that affected most of the Northern Great Plains. The 3rd-driest calendar year on record for Wyoming, with 72% of normal precipitation. Extremely dry summer led to huge wildfires in the Yellowstone region.

Wyoming Climate Atlas

NOAA NCEI: Climate at a Glance

WY Statewide   2002     Drought   The worst year of what was by some measures a 9-year drought (2000-2008). The statewide summer Palmer Drought Index was -8.7, the lowest on record.

Wyoming Climate Atlas

NOAA NCEI: Climate at a Glance

WY Statewide   2012     Drought   The driest calendar year on record for Wyoming, with 69% of normal precipitation. Spring and summer were especially dry, at 55% of normal. Livestock producers were heavily impacted. NOAA NCEI: Climate at a Glance
WY Big Horn, Campbell, Converse, Crook, Johnson, Natrona, Sheridan, Washakie, Weston, Niobrara   2013 10 3-5 Winter Storm 3   An intense moisture-laden storm combined with a push of unseasonably cold air from Canada to produce blizzard conditions and very heavy snowfall over eastern Wyoming, western South Dakota, and the adjacent Plains states. A chilling rain turned to snow, accompanied by 50-70 mph gusts, causing extensive livestock mortality, estimated at 60,000-100,000 head of cattle across the region. The western Black Hills in Crook County received up to 5 feet of snow.

NWS Rapid City WFO: Event Summary

NOAA WPC: Meteorological Analysis