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Local Rainstorms

Some of the Area's Rainstorms

   Local Notable Historical Storms and Data:
         Main Past Storms Page | Storm Reports | Tornadoes | Snow | Rain & Floods | Windstorms

The rainy season in western Oregon runs from October through May, while eastern Oregon experiences its rainy, or snowy, season from late autumn through early spring. Strong storm systems develop in the upper level flow over the Pacific during the rainy season, bringing rain to the lower elevations and snow to the higher elevations. Occasionally, a sub-tropical feed of moisture often referred to as the Pineapple Connection, will be tapped by the stronger storms. The Pineapple Connection is just a term used to describe a continous stream of upper level moisture originating from the tropics, often near Hawaii. This stream of moisture is warm and as a result the air can hold more moisture. The subtropical moisture will enhance the precipitation process in the storms, producing more precipitation than would normally be expected. Flooding can occur if the several storms move across the same area in succession, with heavy snow falling in the higher terrain. There is at least one subtropical connection that brings heavy rain to some part of the Pacific Coast nearly every year. The key to how much precipitation falls during a storm is closely related to how strong and persistent the subtropical connection is.

Another process that brings heavy rain to Oregon occurs during the spring and summer months. Thunderstorms can produce heavy precipitation is a very short amount of time, sometimes on the order of minutes. Again, a strong feed of upper level moisture can enhance the rainfall. However, the source of upper level moisture can vary during the summer. Often the feed of moisture originates over the southwestern United States, often as an extension of the monsoon moisture from Baja California. Monsoon moisture comes from the tropics of Mexico as a result of clockwise circulation around a large high pressure area over the southern Rocky Mountains. In addition, weaker Pineapple connections occur, but are often short-lived.

  1. November 24 to 26, 1999
    [This narrative written by George Taylor, Oregon Climate Service]

    An intense rain storm caused by a flow of warm, moist air from the southwest, struck Oregon on Wednesday and Thursday, November 24 to 25. This marked the first truly intense winter storm of the season, following a relatively dry and mild fall in most of Oregon. Rainfall totals were very high. Tillamook recorded 3.98 inches in 24 hours (and now has over 24 inches for the month), Newport had 3.07 inches, and Florence received 3.63 inches. Willamette Valley totals included over 4 inches in 2 days at Corvallis, 2.4 inches in two days in Salem, and 3 inches in 3 days in Eugene. Clay Creech of the Hatfield Marine Science Center in Newport sent a chart showing hourly precipitation (and cumulative 2-day total) for Nov. 24-25 at the Center, from the National Weather Service gage located there. Note how the highest rainfall intensities occurred Thursday evening (during supper?). Note also the 2-day total -- more than 10 inches!

    In the Coast Range, rainfall was even heavier. John Kwait of Siuslaw National Forest (USFS) sent data from several Remote Automated Weather Stations (RAWS) stations: Cedar (southern Tillamook County), Cannibal Mountain (northwest Lane County) and Dunes (along the coast just south of Florence). Considering that Oregon's all-time one-day record is 11.65 inches, Cedar's total on November 25th is rather significant! Here are the daily totals for the 25th and 26th:

    Range of Thanksgiving Day 1999 Rainstorm Totals (inches)
    Location Nov 25 Rainfall Nov 26 Rainfall
    Cedar (near Tillamook) 11.00 5.54
    Cannibal Mountain 3.92 4.33
    Dunes (near Florence) 1.68 1.83

    Rains were of sufficient duration and intensity to produce local flooding in many parts of Oregon and Washington. The daily river gage plots for the Siletz River on the central coast and the Trask River on the north coast showed how quickly and how high the river levels rose. River levels fell in a few days in most places, but remained somewhat high.

  2. Floods of February 1996 [several historical photos][ table of flood crests ]
    In early February 1996 four days of heavy rain began after a period of extended, bitter cold. Low level snow packs released up to 10 inches of water in as little as 48 hours. Five people died and nearly every Oregon county received a disaster declaration. Region-wide damage estimates exceeded one billion dollars. Thousands were sheltered and hundreds of homes were destroyed. The City of Portland erected a makeshift flood barrier to prevent flood waters from moving into the downtown area.

    For more in-depth information on the February 1996 floods see this summary written by George Taylor of the Oregon Climate Service.

  3. November 18 to 20, 1996
    [This narrative written by George Taylor, Oregon Climate Service]

    Record-breaking precipitation throughout much of Oregon caused local flooding, landslides, and power outages over much of the state during November 18-20. The rain resulted from a broad upper-air weather system of moist subtropical air which originated over the tropical Pacific. The air mass reached central California over the previous weekend, producing rainfall daily amounts as much as 8 inches. Gradually the system moved northward, reaching southwestern Oregon on the 17th and spreading to the remainder of the state the following day. High rainfall amounts were reported throughout the state.

    The infrared satellite image for November 18 shows the areas of warm and cold air over the Northwest. To the north of the frontal boundary, the air mass was quite cool; snow was reported from Portland northward into Washington. South of the front, very mild air and heavy rains prevailed. Winds were also very strong, exceeding 70 mph at some coastal locations in southern Oregon.

  4. December 20 to 24, 1964
    The December 1964 rainstorm was undoubtedly the most severe rainstorm to ever occur over central Oregon, and among the most severe over western Oregon since the late 1870s. Several observing stations across central Oregon recorded two-thirds of their normal annual rainfall in just 5 days. Scores of stations set new records for both 24-hour totals and December monthly rainfall totals. Widespread severe flooding occurred, with at least 30 major highway bridges receiving such damage as to make them unuseable! The new John Day multi-million dollar bridge was destroyed as were scores of bridges on county and secondary roads. Hundreds of miles of roads and highways were washed out or badly damaged. Thousands of people had to be evacuated due to ensuing floods. The Willamette River at downtown Portland had a stage of 29.8 feet. This was a record high for the winter season, and was within inches of the peak stage during the Columbia River spring flood of 1948. Hundreds of homes and other buildings were destroyed and an even greater number were badly damaged. Following is a table of December 1964 rainfall totals and the normal rainfall for December.

    December 1964 Rainstorm Totals (inches)
    Location December 1964 Normal December Rainfall Comments
    Albany 12.55 6.75 none
    Arlington 6.87 1.33 Record December rainfall
    Ashland 11.28 6.74 Record December rainfall
    Bend 8.74 1.73 Record December rainfall
    Crater Lake 38.47 11.69 Record December rainfall
    Detroit 30.86 12.83 Record December rainfall
    Eugene 20.99 6.61 Record December rainfall
    Falls City 27.05 13.83 none
    Government Camp 28.62 12.78 none
    Grants Pass 16.06 5.52 Record December rainfall
    Heppner 4.40 1.38 Record December rainfall
    Illahe 41.43 16.76 Record December rainfall
    Lakeview 8.96 1.88 Record December rainfall
    Medford 12.72 3.38 Record December rainfall
    Newport 20.94 11.02 none
    Pendleton 3.23 1.49 none
    Portland, downtown 11.45 7.42 none
    Portland, airport 9.97 6.38 none
    Reedsport 22.01 11.94 none
    The Dalles 9.05 2.36 Record December rainfall
    Valsetz 40.25 22.27 Record December rainfall

  5. July 13, 1956, near Mitchell, Oregon
    A small, but very intense thunderstorm occurred just north and east of Mitchell, located in north central Oregon in Wheeler county. The region is drained by Bridge Creek, which flows through the center of Mitchell and is usually less than twelve inches deep during July. Within minutes, Bridge Creek became a raging torrent of water that swept buildings away easily. The raging water completely destroyed or heavily damaged twenty buildings in the town center, and washed out several bridges and sections of highway. The observing station was carried away in the flood so no record of actual rainfall is available. Immediately after the flash flood, a United States Geological Survey person visited the region. After careful surveying, he estimated that in fifty minutes, about 3.5 inches of rain fell, and at the storm's center, nearly 4.0 inches fell.

  6. November 22 to 24, 1953
    Rainfall was very heavy over western Oregon, with the heaviest rain occurring over the southern coastal area. At the peak of the storm, most observing stations along the south Oregon coast reported 24-hour rainfall totals of 4 to 7 inches and 72-hour totals of 6 to 10 inches. Widespread heavy flooding occurred in all southwest Oregon streams and in most tributaries and the mainstem Willamette River. Here are some rainfall totals:

    Some November 1953 Rainstorm Totals (inches)
    Location 1 day Rainfall Storm Total
    Gold Beach 6.56 9.80
    Port Orford 4.84 7.25
    Powers 5.00 7.76
    Reedsport 4.45 7.34
    Sitkum 5.72 9.97
    Valsetz 5.84 10.22

  7. January 16 to 19, 1953
    The heaviest rain fell over the south coastal areas, where 24-hour rainfall totals were generally 4 to 8 inches, and storm totals of 15 to 20 inches were common. Here are some of the more spectacular rainfall totals:

    Some January 1953 Rainstorm Totals (inches)
    Location 1 day Rainfall Storm Total
    Bandon 4.00 8.72
    Brookings 6.19 14.14
    Cape Blanco 6.31 15.77
    Denmark 8.07 16.24
    Gold Beach 6.46 16.41
    Illahe 7.17 17.37
    Port Orford 5.80 14.03
    Reedsport 4.11 8.52
    Valsetz 5.40 15.05
    Williams 4.26 9.77

  8. October 26 to 29, 1950
    This strong storm extended over the entire state, but reached its greatest intensity over southwestern Oregon and the higher elevations of the Cascades. In western Oregon, storm totals generally ranged between 10 and 12 inches in the extreme south, gradually decreasing to near 4 inches at the Columbia River. Even in the drier part of central Oregon, heavy rainfall occurred. About one-fourth of observing stations in eastern Oregon reported 24-hour rainfall totals that were greater than their normal October rainfall! Here are some of the rainfall totals from around the state:

    Some October 1950 Rainstorm Totals (inches)
    Location 1 day Rainfall Storm Total
    Bend 2.72 4.98
    Brookings 4.68 11.50
    Cascade Locks 2.31 4.89
    Cottage Grove 4.15 7.73
    Crater Lake 5.17 9.30
    Chemult 2.00 4.10
    Glendale 4.49 11.81
    Grants Pass 5.27 10.76
    Illahe 5.42 14.80
    Odell Lake 5.01 9.06
    Persist 4.78 10.04
    Sexton Summit 4.22 9.52

  9. December 26 to 29, 1945
    This rainstorm began over western Oregon late on the 26th and was over by late on the 28th. Most rainfall fell on the 27th and 28th. During the peak of the storm, western Oregon 24-hour rainfall totals of 3 to 5 inches were not uncommon. Illahe, located in southwestern Oregon in eastern Curry county, reported a 24-hour rainfall total of 8.25 inches of rain, and received 12.91 inches during the entire storm. Heavy precipitation fell across central Oregon as well. Several observing stations in north-central Oregon reported 24-hour rainfall totals of 3 to 5 inches, and storm totals of 4 to 6 inches.

  10. December 26 to 30, 1937
    While the entire state received some precipitation from the storm, it was only in the northwestern Oregon that rainfall amounts were heavy. Two-thirds of the observing stations in northwestern Oregon reported 24-hour rainfall totals of 2 inches or more and at least a third of those stations had 24-hour rainfall totals of 3 inches or more. Here are some of the rainfall totals from around northwestern Oregon:

    Some December 1937 Rainstorm Totals (inches)
    Location 1 day Rainfall Storm Total
    Falls City 5.50 15.35
    Portland Headworks 4.20 10.17
    McNamers 5.15 17.13
    Newport 3.83 8.90
    Portland 5.01 9.34
    Valsetz 7.86 24.00
    Zigzag 3.91 11.50
    Corvallis 5.37 16.24

  11. November 19 to 21, 1921
    Unusually heavy rainfall occurred over most of the state, but the heaviest was over the northwest and north-central Oregon. Here are some of the rainfall totals:

    Some November 1921 Rainstorm Totals (inches)
    Location 1 day Rainfall Storm Total
    Cascadia 4.69 8.59
    Estacada 4.50 8.56
    Government Camp 4.96 11.19
    Portland Headworks 5.13 11.22
    Mount Angel 5.10 9.00
    Portland 4.13 6.71
    Welches 6.55 11.93
    Hood River 4.05 8.64
    The Dalles 4.20 8.90
    Moro 2.25 3.20
    Wasco 2.23 3.69

  12. November 18 to 24, 1909
    This was actually two storms following each other in rapid succession with no significant break in the weather between the first and second. During the seven days period, rainfall totals were 10 to 20 inches along the coast, 4 to 6 inches in the western inland valleys, 7 to 14 inches along the western Cascades slopes, and only 1 to 3 inches in eastern Oregon. Along the coast and in the upper western Cascades, 24-hour totals of 4.50 to 5.50 inches were common. At least 80% of the stations west of the Cascades received one inch or more and 24-hour totals of at least 2 inches, with several stations receiving 3.00 inches or more.

  13. June 14, 1903, near Heppner and Ione [historical photo]
    This was surely the most deadly natural disaster in Oregon's recorded history. A strong thunderstorm, accompanied by extremely heavy rain and hail, moved near Heppner, Oregon. The storm covered a very small area, probably no more than 50 square miles. Heavy rain fell in a very short time, creating severe flash flooding along Willow Creek, normally a peaceful stream flowing through the town center. The entire town was swept away in just a few short minutes, drowning nearly 247 people. Eyewitnesses say thunderstorm rains arrived as a 40-foot wall of water and the ensuing flood raged through town for over an hour. In all, one-third of the towns' structures were wiped out. The massive runoff of water was a result of heavy rain falling on the barren rocky hills, then flowing into the Willow Creek watershed. Only fifteen minutes separated the first rainwater in Willow Creek at Heppner and the flood crest! There are no rainfall records available for this storm because the weather observing station was completely destroyed, drowning the observer and his entire family.

    A similar fate would have been in store for the citizens of Ione, just 20 miles downstream. However, telephoned warnings prompted an immediate evacuation and residents escaped to high ground. At least 150 homes were destroyed at Ione and bodies were washed more than 40 miles downstream to the Columbia River.

  14. November 12 to 17, 1896
    Heavy precipitation fell over the full length of the Oregon coast and inland over the northern three-fourths of the state west of the Cascades. Between the 12th and 17th of November 1896, 15 to 20 inches fell in the coastal areas, and 5 to 10 inches fell further inland. Maximum 24-hour totals of five to seven inches were observed at many coastal observing stations. Most of the Willamette valley locations reported 24-hour totals were of at least two inches.

  15. January 28 to February 3, 1890
    Very heavy rainfall fell over most of western Oregon, particularly along the coast and in the Willamette valley. The seven-day totals ranged from 15 to 20 inches along the coast with 26.52 inches at Glenora in Tillamook County. Rainfall in the Willamette valley was generally between 10 and 15 inches, while 5 to 10 inches fell in the southwestern interior valleys. Precipitation east of the Cascades was light.

  16. December 12 to 13, 1882
    In Portland, one 24-hour period had 7.66 inches of rain and the two-day total was 10.75 inches. It is not known how widespread precipitation approaching this intensity may have been due to the very few existing observing stations at that time. From the limited information available, however, it appears that the heavy rainfall was only in northwest Oregon.

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