May 28, 2009 in Washington Voices

Spring is season for regional flooding

Randy Mann
 

Although many of us certainly enjoyed the nice weather over the Memorial Day weekend, warm temperatures did raise some flooding concerns along the upper Yakima River and the Stehekin River due to rapid snowmelt.

Many of us have seen lowland flooding in the winter months, but the Inland Northwest sees its greatest risk of high waters during the spring season. They typically result from thunderstorms or warm rains falling on melting snowpacks in the higher elevations.

Much of this flooding occurs in the foothills of the Cascade Mountains and in the highlands of northeastern Washington, as well as across portions of North Idaho and Western Montana around this time of year. A disastrous flood hit the Flathead Valley in northwestern Montana in June 1964.

Historically, Western Washington and the Inland Northwest have seen their share of high waters. In November 1990, there was widespread major flooding on Western Washington and several Eastern Washington rivers. The Interstate 90 Lake Washington floating bridge actually sank. Two deaths were recorded and damage was estimated at $250 million.

In February 1996, widespread flooding was seen in Washington, Oregon and Idaho. Major flooding occurred in North Idaho. Three deaths were reported in Washington with overall damage in the region estimated at a staggering $800 million.

Perhaps the worst flood in recent times across our region happened in May and June of 1948. Known as the “Greatest Spring Snowmelt Flooding,” this event is listed as the second-biggest weather event in Washington’s history.

During that time, there was widespread flooding in North Idaho and Eastern Washington, especially along the Columbia River. Below Priest Rapids in Eastern Washington, the Columbia River topped at 458.65 feet, an all-time record. Flood stage is 432 feet.

At Lake Pend Oreille near Hope, Idaho, a crest of 2,071.2 feet was measured with a flood stage of 2,063.5 feet. From now into late June, there may be a few flood advisories along lowland areas near streams and rivers due to occasional showers, thunderstorm activity and snowmelt. May is coming to an end, but there is still some snow left in the higher elevations.

Contact Randy Mann at www.longrangeweather.com.


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