Fig. 1 An AR on 9 January 1995 caused substantial damages on the west coast of the United States. (A) 4 National Center of Environmental Prediction–National Center for Atmospheric Research (NCEP-NCAR) precipitable water preceded peak damages in California. (B) Maximum coastal IVT (given here over the entire west coast), generated peak precipitation over Sonoma County (see Materials and Methods), streamflow at the U.S. Geological Survey Guerneville gauge, and total insured losses in Sonoma County. (C) Flood insurance claims along the lower reach of the Russian River in Sonoma County are marked as red dots; the 100-year flood plain is indicated in blue.
Fig. 3 Flood damages increase exponentially with AR category. (A) The Ralph et al. AR scale (20) classifies ARs into five categories depending on IVT and duration. For example, an AR with a peak IVT of 800 kg m−1 s−1 and a duration of 78 hours is classified as a category 4 or extreme AR. (B) NDJFM flood damages increase exponentially with AR category: Vertical scale is logarithmic; black bars are medians; boxes are 25th and 75th percentiles, and whiskers are 5th and 95th percentiles; dots are extrema; numbers in parentheses are the number of NDJFM events in each category. Note that the total number of ARs in the Gershunov AR catalog (1603) is greater than the number of ARs over the sample period using the Ralph et al. AR scale (1134), which classifies events with a duration of less than 24 hours as non-ARs.
- Table 1 Most damaging atmospheric rivers 1978–2017.
Start date Initial landfall
regionInitial landfall
latitudeAR category Peak IVT
(kg m−1 s−1)Claims Insured losses
($m)Total damages
($b)4 January 1995 S. CA 32.5°N 4 966 4725 125.8 3.7 29 December
2005N. CA 40°N 4 825 2554 117.6 3.5 29 December 1996 Central CA 35°N 5 1260 3407 104.6 3.1 5 February 1996 N. OR 45°N 3 729 2695 99.3 3.0 2 December 2007 N. OR 45°N 5 1258 1447 83.9 2.5 15 February 1986 WA 47.5°N 4 870 2048 66.6 2.0 7 March 1995 S. OR 42.5°N 4 928 2343 58.7 1.8 5 January 2009 S. OR 42.5°N 4 831 1636 53.9 1.6 1 February 1998 Bay Area 37.5°N 4 795 2417 46.8 1.4 1 November 2006 N. CA 40°N 5 1041 1184 38.7 1.2 25 January 1983 Bay Area 37.5°N 5 1013 1545 34.9 1.0 25 February 1983 Bay Area 37.5°N 3 658 1832 30.0 0.9 12 February 1980 Baja CA 30°N 3 721 2059 28.5 0.9 3 January 1982 N. CA 40°N 3 525 1422 28.1 0.8 11 February 1986 N. CA 40°N 4 904 848 23.9 0.7 21 November
1990WA 47.5°N 4 943 939 23.3 0.7 - Table 2 Proportion of losses caused by ARs in top counties.
County AR proportion of
insured lossesClaims Insured losses ($m) Total damages ($b) AR damages ($b) Sonoma, CA 0.998 6650 172.0 5.2 5.2 Los Angeles, CA 0.846 8280 106.1 3.2 2.7 Lewis, WA 0.989 1979 101.4 3.0 3.0 Marin, CA 0.987 3152 73.2 2.2 2.2 King, WA 0.970 2915 69.0 2.1 2.0 Sacramento, CA 0.977 3609 56.9 1.7 1.7 Snohomish, WA 0.903 1818 43.7 1.3 1.2 Monterey, CA 0.989 1253 43.5 1.3 1.3 Napa, CA 0.997 1331 43.2 1.3 1.3 Washoe, NV 0.998 720 42.4 1.3 1.3 Maricopa, AZ 0.628 2368 33.7 1.0 0.6 Santa Clara, CA 0.971 1557 33.4 1.0 1.0 Clackamas, OR 0.970 730 31.5 0.9 0.9 San Diego, CA 0.912 1945 30.7 0.9 0.8 Orange, CA 0.899 3619 29.3 0.9 0.8 Pierce, WA 0.974 934 28.4 0.9 0.9 Riverside, CA 0.624 1619 27.9 0.8 0.5 Cowlitz, WA 0.596 709 26.6 0.8 0.5 Placer, CA 0.990 598 26.5 0.8 0.8 Columbia, OR 0.998 414 24.7 0.7 0.7 - Table 3 Summary statistics of damages by atmospheric river category, November to March, in millions of dollars.
Damages under $50,000 are rounded down to $0.
AR CAT Number of
eventsMinimum
($m)5% ($m) 25% ($m) Median ($m) 75% ($m) 95% ($m) Maximum
($m)CAT 1 130 0 0 0 0.1 1 24 208 CAT 2 168 0 0 0 0.3 4 48 844 CAT 3 201 0 0 0.1 2 10 94 2930 CAT 4 99 0 0.1 3 19 85 1424 3773 CAT 5 11 3 5 24 259 1102 2821 3126 All ARs 609 0 0 0 2 10 197 3773
Supplementary Materials
Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/12/eaax4631/DC1
Supplementary Text
Fig. S1. Coastal grid cells.
Fig. S2. NFIP payments versus NWS damages.
Fig. S3. Distribution and time course of insured losses.
Fig. S4. Spatial footprints of ARs.
Fig. S5. Seasonality of insured losses.
Fig. S6. Days with over $1 million in insured losses.
Table S1. Damages by AR category by month, in millions of dollars.
Table S2. Effect of antecedent ARs on mean flood damages by AR event.
Table S3. Average claims and insured losses per latitude-day by AR intensity (quartiles).
Table S4. Daily average insured losses by latitude band by AR intensity.
Data S1.
Reference (41)
Additional Files
Supplementary Materials
The PDFset includes:
- Supplementary Text
- Fig. S1. Coastal grid cells.
- Fig. S2. NFIP payments versus NWS damages.
- Fig. S3. Distribution and time course of insured losses.
- Fig. S4. Spatial footprints of ARs.
- Fig. S5. Seasonality of insured losses.
- Fig. S6. Days with over $1 million in insured losses.
- Table S1. Damages by AR category by month, in millions of dollars.
- Table S2. Effect of antecedent ARs on mean flood damages by AR event.
- Table S3. Average claims and insured losses per latitude-day by AR intensity (quartiles).
- Table S4. Daily average insured losses by latitude band by AR intensity.
- Reference (41)
Other Supplementary Material for this manuscript includes the following:
- Data S1 (Microsoft Excel format).
Files in this Data Supplement:
