Notable Atmospheric River Events

Events are listed in chronological order and are required to have appeared in a peer-reviewed publication in order to be included on this page. Click gray bar to expand details of event.

1986 Northern and Central CA

Photo by Mark Holloway

11–24 February

Precipitation
  • Event rainfall total of 49.6 inches at Bucks Lake in Feather River Basin
  • Event rainfall totals of 20–30 inches were common throughout central and northern CA
  • 24-h rainfall total of 17.60 inches on 17 Feb at Four Trees, CA
  • 29 inches over 10 days at Calistoga, CA
Streamflow
  • Several rivers above flood stage.
  • 23% of streamflow gaging stations in CA reported significant discharges
  • Russian River near Guerneville, CA crested at 48.56 ft with peak discharge of 102,000 ft3/s; >50 yr recurrence interval
  • Napa River near Napa, CA crested at 30.2 ft with peak discharge of 37,100 ft3/s; 75-100 yr recurrence interval
Societal Impacts
  • 13 fatalities, 67 injuries
  • 50,000 people displaced by flooding
  • $400 million in damages to property and infrastructure.
Related Publication
Leung L. R, and Y. Qian, 2009. Atmospheric rivers induced heavy precipitation and flooding in the Western U.S. simulated by the WRF regional climate model. Geophys. Res. Lett., 36, L03820, doi:10.1029/2008GL036445.
Related Links

1996/1997 Northern California and Western Nevada

Photo by Mark Holloway

29 December – 4 January

Precipitation
  • Event rainfall totals of >24 inches in many locations throughout northern California.
  • Heavy rain at high elevations in the Sierra Nevada fell on top of deep snow pack exacerbated runoff and river flooding
Streamflow
  • Several rivers above flood stage; record peak river flows were recorded at 106 gauging stations for event.
  • San Joaquin, Sacramento, Feather, Cosumnes, and Toulumne Rivers heavily impacted.
  • San Joaquin River near Auberry crested at 65.17 ft with a peak discharge of 99200 ft3/s; >75 year recurrence interval.
  • Sacramento River at Delta, CA crested at 25.21 ft with a peak discharge of 62,300 ft3/s; 50-75 yr recurrence interval.
  • North Fork Feather River at Grizzly Creek, CA crested at 29.97 ft with a peak discharge of 115,000 ft3/s; >100 yr recurrence interval.
  • Cosumnes River at Michigan Bar, CA crested at 18.54 ft with peak discharge of 93,000 ft3/s; >100 yr recurrence interval.
Societal Impacts
  • 250 square miles inundated by flood waters
  • 2 fatalities, 50 injuries.
  • 120,000 people displaced by flooding.
  • $1.6 billion in damages; 20000 homes and 1500 businesses destroyed or damaged.
  • Disaster areas declared in 43 counties in CA.
  • Multiple levees along the Sacramento and San Joaquin Rivers broke due to extremely high runoff from melting snow and heavy rainfall.
  • The Feather River fish hatchery and the San Joaquin River fish hatchery were virtually destroyed.
Related Publications
Galewsky, J., A. Sobel, 2005: Moist dynamics and orographic precipitation in northern and central California during the New Year's Flood of 1997. Mon. Wea. Rev., 133, 1594-1612, doi:10.1175/MWR2943.1.
Leung L. R, and Y. Qian, 2009. Atmospheric rivers induced heavy precipitation and flooding in the Western U.S. simulated by the WRF regional climate model. Geophys. Res. Lett., 36, L03820, doi:10.1029/2008GL036445.
Related Links

1998 Central California Coast, Santa Cruz Mountains

Photo by Kita

2–3 February

Precipitation
  • 14 inches in 45 h at many locations in the Santa Cruz Mountains
Streamflow
  • Various creeks and rivers at flood stage in the Santa Cruz Mountains.
  • Pescadero Creek at Pescadero, CA crested at 22.47 ft with a peak discharge of 10,600 ft3/s; 25-50 yr recurrence interval.
  • San Benito River at Hollister, CA crested at 13.48 ft with peak discharge of 34,500 ft3/s; 50-75 yr recurrence interval.
  • Tres Pinos Creek at Tres Pinos, CA crested at 16 ft with a peak discharge of 27,200 ft3/s; 75-100 yr recurrence interval.
  • San Lorenzo Creek at San Lorenzo, CA crested at 14.27 ft with a peak discharge of 10,300 ft3/s; 75-100 yr recurrence interval.
Societal Impacts
  • Worst flooding struck the relatively sparsely populated Pescadero Creek basin, resulting in limited adverse societal impacts.
  • Forecasters issued flood warning 6 h before flooding began, allowing residents to be evacuated before flooding began.
Related Publication
Ralph, F. M., P. J. Neiman, D. E. Kingsmill, P. O. G. Persson, A. B. White, E. T. Strem, E. D. Andrews, and R. C. Antweiler, 2003: The impact of a prominent rain shadow on flooding in California's Santa Cruz mountains: A CALJET case study and sensitivity to the ENSO cycle. J. Hydrometeor., 4, 1243-1264, doi:10.1175/1525-7541(2003)004<1243:TIOAPR>2.0.CO;2.
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  • Worst flooding struck the relatively sparsely populated Pescadero Creek basin, resulting in limited adverse societal impacts.
  • Forecasters issued flood warning 6 h before flooding began, allowing residents to be evacuated before flooding began.

2004 Northern California, Russian River Basin

Russian River, Photo by Finlay McWalter

16–18 February

Precipitation
  • >10 inches of rainfall in 60 h over the coastal mountains
  • Rainfall totals of 4–7 inches throughout the Russian river watershed
Streamflow
  • Many rivers throughout coastal northern CA had flows within the top 0.2% of the historical observations during the event.
  • The Russian River's discharge on 18 Feb ranked 35th among all days on record.
Sociental Impacts
  • No major societal impacts
Related Publication
Ralph, F. M., P. J. Neiman, G. A. Wick, S. I. Gutman, M. D. Dettinger, D. R. Cayan, and A. B. White, 2006: Flooding on California's Russian River: Role of atmospheric rivers. Geophys. Res. Lett., 33, L13801, doi:10.1029/2006GL026689.

2005 Southern California

rockslide on road

7–11 January

Precipitation
  • Event rainfall totals of 10–20+ inches throughout southern CA, with heaviest rainfall focused north and east of Los Angeles, CA.
Streamflow
  • Several rivers throughout southern CA exceeded flood stage.
  • Ventura River at Ventura, CA crested at 17.5 feet with a peak discharge of 152,560 ft3/s.
  • Santa Ynez River at Narrows, CA crested at 18.1 ft with a peak discharge of 27,386 ft3/s.
  • Santa Clara River at Freeman Diversion crested at 171 ft with a peak discharge of 383,164 ft3/s.
Societal Impacts
  • 14 fatalities, 9 injuries.
  • Several hundred people displaced by flooding.
  • $200–300 million in damages.
  • Several structures destroyed by flash flooding.
  • Several road ways compromised by mudslides and flooding.
  • Major mudslide at La Conchita in Ventura County, CA, resulted in 10 fatalities and destroyed 15 homes.
Related Publication
Ralph, F. M., P. J. Neiman, G. N. Kiladis, K. Weickman, and D. W. Reynolds, 2011: A multi-scale observational case study of a Pacific atmospheric river exhibiting tropical-extratropical connections and a mesoscale frontal wave. Mon. Wea. Rev., 139, 1169-1189, doi:10.1175/2010MWR3596.1.
Related Links

2005 Western Oregon and Western Washington

25–27 March

Precipitation
  • Event rainfall totals of 2–8 inches throughout western Oregon and western Washington
Streamflow
  • Due to antecedent drought conditions, streamflow in most rivers did not reach significant flooding levels.
  • The Nehalem River stream gauge near Foss, OR recorded a peak discharge of 15,662 ft3/s, just surpassing flood level.
Societal Impacts
  • No major societal impacts
Related Publication
Ralph, F. M., P. J. Neiman, G. N. Kiladis, K. Weickman, and D. W. Reynolds, 2011: A multi-scale observational case study of a Pacific atmospheric river exhibiting tropical-extratropical connections and a mesoscale frontal wave. Mon. Wea. Rev., 139, 1169-1189, doi:10.1175/2010MWR3596.1.

2005 Western Norway

missing bridge from flood

13–14 September

Precipitation
  • Rainfall total of 6.16 inches in 24 h at the Bergen-Florida weather, the most daily rainfall ever recorded at the site since observations began there.
  • Rainfall total of 7.06 inches in 24 h at Opstveit, the most daily rainfall ever recorded in September in Norway.
Societal Impacts
  • Landslides at Hatlestad Terrasse near Bergen caused 3 fatalities and 7 injuries and destroyed several homes, displacing several people.
  • Flooding and landslides caused severe damage to buildings and infrastructure around the city of Bergen.
  • Strong winds downed powerlines and trees, adversely affecting communications and transportation.
Related Publication
Stohl, A., C. Forster, and H. Sodemann, 2008: Remote sources of water vapor forming precipitation on the Norwegian west coast at 60° N - a tale of hurricanes and an atmospheric river. J. Geophys. Res., 113, D05102, doi:10.1029/2007JD009006.
Related Links

2005/2006 Northern California

29 December – 2 January

Precipitation
  • Event rainfall totals >20 inches throughout the Sierra Nevada.
  • Locations in the Coastal Range in the Russian and Napa River basins received 18–30 inches.
  • Widespread 24-h rainfall totals in excess of 5 inches on 31 Dec throughout Northern CA.
Streamflow
  • Several rivers above flood stage throughout northern CA.
  • Recurrence intervals for peak discharges throughout northern CA ranged from 10-25 yrs.
  • Russian River near Guerneville, CA crested at 44.21 ft with peak discharge of 85,800 ft3/s; 10-25 yr recurrence interval.
  • Napa River near Napa, CA crested at 29.85 ft with peak discharge of 29,600 ft3/s; 10-25 yr recurrence interval.
  • Sonoma Creek at Agua Liente, CA crested at 32.51 ft with peak discharge of 17,600 ft3/s; >100 yr recurrence interval.
  • Kalmath River near Kalmath, CA crested at 47.12 ft with peak discharge of 416,000 ft3/s; 25-50 yr recurrence interval.
Societal Impacts
  • Major flooding concentrated in Napa and Russian River basins.
  • No fatalities reported.
  • $300 million in damages.
  • 10 counties declared federal disaster areas.
  • 1000 homes were flooded in Napa, CA.
  • Various local evacuations, road closures, slope failures (i.e., mudslides).
Related Publication
Smith, B.L., S.E. Yuter, P.J. Neiman, and D.E. Kingsmill, 2010: Water vapor fluxes and orographic precipitation over northern California associated with a land-falling atmospheric river. Mon. Wea. Rev., 138, 74-100, doi:10.1175/2009MWR2939.1.
Related Links

2006 Western Washington and Northern Oregon

Photo by Kimberly White

6–7 November

Precipitation
  • Event rainfall totals of 8–20 inches over the Cascades and Coastal Mountains
  • Local rainfall maxima near 28 inches in the Coastal Mountains and near 24 inches in the Cascades
Streamflow
  • Several rivers above flood stage in western WA.
  • Several stream gauges throughout the Coastal and Cascade mountain ranges in western WA and northern OR recorded 1-day discharges in the top 1% of those historically recorded, with 6 gauges reporting record discharges.
Societal Impacts
  • No fatalities reported.
  • ~$50 million in damages.
  • Several roadways washed away by flood waters.
  • Mudslides blocked roadways leading to road closures.
Related Publication
Neiman, P. J., F.M. Ralph, G.A. Wick, Y.-H. Kuo, T.-K. Wee, Z. Ma, G.H. Taylor, and M.D. Dettinger, 2008b: Diagnosis of an intense atmospheric river impacting the Pacific Northwest: Storm summary and offshore vertical structure observed with COSMIC satellite retrievals. Mon. Wea. Rev., 136, 4398-4420, doi:10.1175/2008MWR2550.1.
Related Links

2009 Western Washington

Photo by John Gorton

6–8 January

Precipitation
  • Event rainfall totals of 3–8 inches throughout western Washington.
  • Rainfall totals alone didn't lead to flooding; melting snow and saturated soils lead to increased runoff into several river basins.
Streamflow
  • Several rivers above flood stage, with near record crests recorded throughout western WA.
  • The Snoqualmie River near Carnation, WA crested at 62.31 ft (>7 ft above flood stage), breaking the previous record of 61.17 ft.
Societal Impacts
  • No fatalities reported.
  • 30,000 people were instructed to evacuate.
  • $125 million in damages.
  • Flooding lead to the closure of a 20 mile stretch of Interstate Highway 5 and to the closure of Amtrak lines out of Seattle, WA.
Related Publication
Neiman, P. J., L. J. Schick, F. M. Ralph, M. Hughes, and G. A. Wick, 2011: Flooding in western Washington: The connection to atmospheric rivers. J. Hydrometeor., (in press), doi:10.1175/2011JHM1358.1.
Related Links

2009 Northern and Central California

Photo by Marvin Walley

13–14 October

Precipitation
  • Widespread rainfall totals >2 inches throughout central and northern CA
  • Maximum 24-h rainfall totals near 19 inches along central CA coast
  • Maximum 24-h rainfall totals >10 inches in the southern Sierra Nevada
Streamflow
  • Due to dry antecedent conditions, no flood stages were reported.
  • Flash flood warning issued for Dinkey Creek in the southern Sierra Nevada, but it did not reach flood stage.
  • Salinas River, Russian River, and Merced River all reported daily record flows compared to historical 14 October values
Societal Impacts
  • No fatalities reported.
  • Several evacuations due to landslide threat.
  • Landslides reported in the Santa Cruz Mountains and in Sequoia National Park in the Sierra Nevada.
  • Estimated $10 million in damages.
  • High wind gusts (>50 mph) downed trees and power lines.
Related Publication
Ralph, F. M., P. J. Neiman, G. N. Kiladis, K. Weickman, and D. W. Reynolds, 2011: A multi-scale observational case study of a Pacific atmospheric river exhibiting tropical-extratropical connections and a mesoscale frontal wave. Mon. Wea. Rev., 139, 1169-1189, doi:10.1175/2010MWR3596.1.
Related Links

2010 "Snowmageddon" Event, Mid-Atlantic U.S.

Photo by Julian Colton

5–6 February

Precipitation
  • Widespread snowfall totals of 2–3 feet across region.
  • 26.5 inches of snow at Wilmington, DE (all-time record).
  • 28.5 inches at Philadelphia, PA (second all-time heaviest snowfall).
  • 18.2 inches at Atlantic City, NJ (second all-time heaviest snowfall).
  • 24.8 inches at Baltimore, MD (third all-time heaviest snowfall).
  • 17.8 inches at Washington, D.C. (fourth all-time heaviest snowfall).
  • Some locations in Maryland had snowfall totals exceeding 3 ft.
Societal Impacts
  • The U.S. Government temporarily closed its offices.
  • Widespread school closures throughout the Mid-Atlantic region.
  • Nearly 300,000 power outages across Virginia and Maryland.
  • Train, automobile, and air travel was significantly hindered as snow rapidly accumulated on railways roadways, and runways; several automobile accidents reported, widespread flight cancellations.
  • Heavy, wet snow caused several roof collapses throughout the Mid-Atlantic region.
Related Publication
Halverson, J. B. and T. D. Rabenhorst, 2010: Mega-snow in the Megalopolis: The Mid-Atlantic's blockbuster winter of 2009-2010. Weatherwise, 63, 16-23, doi:10.1080/00431672.2010.490164.
Related Links

AR Animation Loop

Animation of GFS forecast of integrated water vapor showing Atmospheric Rivers
Animation of atmospheric river event, February 2014. (CREDIT: NOAA/ESRL Physical Sciences Division)
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