Three Types of Drought in the Pacific Northwest – 2001, 2003, &

2005Karin Bumbaco

Philip MoteOffice of the Washington State Climatologist

University of WashingtonMarch 21, 2009

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What is drought?• “insufficient

water to meet needs”

(Redmond, 2002)

• Defined in terms of its impacts

• Difficult to quantify

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1999-2008 water years compared to 1950-1995 normal

Composite % of normal precipitation

Methods

• Yearly total precipitation and average temperature were ranked (1895-2005) for DJF and JJA for WA and OR

• Monthly average streamflow data at 216 gauges in WA and OR (55 years) were also ranked relative to 2001 and 2003

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2001

• November to March had below average precipitation leading to low snowpack

• 2nd driest DJF 7

2001

• Record low precipitation in Portland, Astoria, Corvallis, and Eugene for the water year– 41-67% of normal

• Driest water year in Hoquiam and Vancouver, 2nd driest in Spokane, 4th driest in Seattle

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WA

OR

• Rank of 2001 DJF streamflow with 55 yrs

• Low streamflow in western WA and OR (many ranking 2nd to 1977)

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Fig: Rob Norheim

2001 Impacts – Agricultural Drought

• Pro-ratable junior water users in Yakima Basin, WA only received 37% of their entitlement– $130 million loss in agriculture revenues

• Klamath Basin, OR had a showdown over water– Suckerfish vs. irrigated water for farmers– $157 million loss in agriculture revenues

• Low river flows resulted in 5,300 MW loss in hydropower in WA ($3.5 billion)

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2003

• May through Sept had below average precipitation• 4th warmest DJF – low snowpack in OR• 2nd warmest and driest JJA

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2003 Impacts

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• 2003 JJA flows low in western WA and OR

• Many forest fires in OR– Booth and

Bear Butte fire – 3.7 million

square meters– State of

emergency Fig: Rob Norheim

2005 - WA• DJF Precipitation was below normal (70-80%)• Snowpack was 20% of normal for the winter

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2005 Impacts - WA• Snowmelt-dominated

streams were low• Drought declared March

10, 2005– Hurt horticulture

industry (lost 8-20% revenue in western WA)

• Ski areas lost 1 million visitors (69% of average 10 yr visitation) = $43 million

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2005 - OR

• More serious precipitation deficit in OR limiting snowpack like 2001

• “Drought plan” was implemented in Klamath Basin in March 2005 – Limited water to 2nd and 3rd priority holders (e.g.

city parks)

• Rains in March and April eased the burden

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Relation to ENSO and PDO?

• 2001 had cold ENSO, cold PDO, and dry Southwest– Indian Ocean warmth in 1999-2002 was

associated with drought in large area of mid-latitudes including the PNW (Hoerling and Kumar, 2003)

– Warmer Indian Ocean could be responsible for drought in recent years

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Summary

• Some droughts form in winter by low precipitation (2001) or a combination of low precipitation and high temperatures (2005) producing low snowpack– Impacts can be anticipated in most cases

• Some form unexpectedly in summer (2003)– Points to the need for better timely information in

summer

• Implications for climate change17

Thanks!

Questions?

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