The Great Plains have experienced severe weather that have altered vegetation and agriculture in the area. Washington State has been famous for being very abundant with rain and snow. I have found that top 10 weather events in the state in the 20th century.
10. November 1990 - Statewide Flooding
* Widespread, major flooding on western Washington rivers, especially the rivers of northwest Washington, and several eastern Washington rivers
* Two deaths
* Damage estimated $250 million
* Interstate 90 Lake Washington floating bridge sank during this flooding event
* Stands as the highest flood of record for many northwest Washington rivers including the Elwha, Cedar, Snoqualmie, Skykomish, Snohomish, and Stillaguamish
9. January/February 1916 - Seattle's Greatest Snowstorm
* Seattle recorded its maximum snowfall ever in a 24 hour period, 21.5" on Feb 1st
* Other parts of western Washington received between 2 to 4 feet of snow
* Winds created snow drifts as high as 5 feet
* Region was crippled, transportation essentially halted
* Seattle Jan snowfall was 23", Feb snowfall 35", total 58 "
8. February 1996 - Widespread Flooding in Washington, Oregon, and Idaho
* Major major flooding on rivers of western and southeast Washington
* Widespread flooding on rivers across much of Oregon
* Major flooding in northern Idaho
* Damage region wide estimated $800 million
* Three deaths in Washington state alone
* Highest flood of record on many southwest Washington rivers, most notably the Chehalis, Skookumchuck, and Nisqually
7. April 5, 1972 - Washington's Deadliest Tornado Outbreak
* An F3 tornado touched down in Vancouver
* 6 deaths and 300 injured, Washington led nation in tornado deaths that year
* Tornado swept through a grocery store, bowling alley, and grade school near where Vancouver Mall is today
* 50 million dollars in damage
* Later that day, another F3 tornado touched down west of Spokane
* And an F2 tornado struck rural Stevens county
* Numerous severe thunderstorms with large hail and damaging winds were reported over other areas of eastern Washington
6. March 1, 1910 - Stevens Pass Avalanche
* The deadliest avalanche in U.S. history occurred near Stevens Pass
* Two trains were swept off the tracks into a ravine, claiming 96 lives.
5. May 18, 1980 - Eruption of Mount St. Helens
* Over 60 lives lost from the eruption and ensuing mud flow on the Toutle river
* Sent an ash plume into parts of Eastern Washington and beyond
* The ash fell like snow, drifting as deep as two feet, crushing crops, halting transportation, and causing schools and businesses to close
* A national monument was formed in the wake of the event
4. August 20 - September 9, 1910 - Massive Forest Fires in Eastern Washington and Northern Idaho
* Three million acres of timber were scorched
* Conflagration created its own weather. Ships in the Pacific Ocean were lost in the smoke, which also reached the Atlantic seaboard
* The flames claimed 85 lives -- 72 of them firefighters
3. January 13, 1950 - The January 1950 Blizzard
* 21.4" of snow fell in Seattle on the 13th together with winds of 25-40 MPH, the 2nd greatest 24 hour snowfall recorded
* Claimed 13 lives in the Puget Sound area
* During Jan, 18 days with high temps 32 degrees or lower
* The winter of 1949-50 the coldest winter on record in Seattle - average temp 34.4 degrees
* Eastern Washington, North Idaho, and parts of Oregon were paralyzed - lower elevation snow depths ranged up to 50 inches and temperatures plunged into minus teens and twenties. Several dozen fatalities.
2. May/June 1948 - Greatest Spring Snowmelt Flooding
*Widespread flooding in northern Idaho, eastern Washington and along the Columbia river to the Pacific Ocean
* Columbia River below Priest Rapids WA, Flood of Record 458.65 FT (FS 432.0 FT)
* Lake Pend Oreille near Hope ID, Flood of Record 2071.2 FT (FS 2063.5 FT)
* Pend Oreille River below Albeni Falls, ID Flow of Record 160000 CFS (FF 100 kCFS)
* Methow River at Pateros WA, Flood of Record stage > 12.30 FT (FS 10.0 FT)
* St. Joe River at Calder, ID Flood of Record 18.10 FT (FS 13.0 FT)
May 30, 1948 - Vanport Flood
* America's largest war-time housing project wiped out in less than one hour as dikes along the Columbia river near Portland gave way
* Vanport never came back and is now Delta Park area of north Portland
* Vancouver, Camas, Kalama, Kelso/Longview also suffered flooding
* Flood lasted 45 days
And the top weather event for Washington state from 1900 - 1999 was:
1. October 12, 1962 - The Columbus Day Wind Storm
* The mother of all wind storms this century, the wind storm all others are compared to
* Strongest widespread non-hurricane wind storm to strike the continental U.S. this century
* Struck from northern California to British Columbia
* Claimed 46 lives, blew down 15 billion, yes, 15 billion board feet of timber ($750 million worth - 1962)
* Total property damage in the region $235 million
* Recorded wind speeds (before power went out)
Naselle - Gust to 150 MPH Bellingham and Vancouver - Gust 92 MPH
Renton - Gust 100 MPH Morrison St Bridge - Gust 116 MPH
Tacoma - Gust 88 MPH Troutdale - Gust to 106 MPH
Mt Hebo - Gust to 131 MPH
Honorable Mentions:
May 31, 1997 - Severe Weather/Tornado Outbreak
* A record six tornados touched down in Washington in one day
* Former record was 4 tornados in 1989 for the entire year
* Four F1 tornados hit Stevens and Spokane counties in northeast Washington
* Two F0 tornados touched down in western Washington - Vancouver and Tacoma
* An F1 tornado also struck Athol and an F0 was observed near Lewiston in Idaho
* In addition, severe thunderstorms produced large hail up to 2 to 3 inches in diameter, heavy rain and flash flooding, and wind gust to near 80 mph
* No deaths or injuries reported
* Washington had a record 14 tornados reported in the state for the year
January 20, 1993 - The Inauguration Day Wind Storm
* Claimed 5 lives, 3/4 million homes and businesses without power
* Total damage in western Washington, $130 million
* Winds in Puget Sound area - gusts 60-70 MPH
Cape Disappointment - gust to 98 MPH
November 19,1996 - Spokane Area Ice Storm
* Up to a half inch of ice deposited or accreted on trees, vehicles, buildings, etc., across much of the populated areas of Spokane and Kootenai counties
* Over 100,00 homes and businesses lost power, some people without power for up to 14 days
* Damage estimated at over 22 million dollars and 4 fatalities
1976-77 - Worst Drought in Pacific Northwest history
* Crop yields well way below normal
* Region wide water rationing and power consumption restrictions
* Area ski resorts were closed for much of the 76-77 ski season
* Significant economic impacts throughout from this event
October 16, 1991 - Spokane Area Urban Interface Wildfire
* Strong winds combined with very dry conditions
* Multiple fires started by downed power lines and other sources
* 2 lives were lost, 100 homes were damaged or destroyed
August 1967 - Eastern Washington/Northern Idaho Heat Wave
* Spokane had 11 consecutive days with 90 degrees and warmer
* Lewiston Idaho observed 11 consecutive days with 100 degree plus heat
Source:
"National Weather Service - NWS Portland." National Weather Service - Western Region Headquarters. Web. 29 Apr. 2011. <http://www.wrh.noaa.gov/pqr/paststorms/washington10.php>.