The Current Status of the Most Important Water Source in the Northwest: The Columbia River

When it comes to our summer water supply, nothing is as important as the Columbia River.

It is the largest regional source of water for agriculture.

Its water is the largest source of power in the region.

Its water supports important salmon runs.  

And Columbia River water is used for drinking purposes in some communities.

This year, the water availability of the Columbia River should be very close to normal, with no hint of drought conditions.

Let's start at the water level of Lake Roosevelt behind Grand Coulee Dam on the Columbia River (below).   The blue color indicates this year's level, which is almost exactly at normal levels (red line).

 

Or we can look at the predicted water supply for April through September at Grand Coulee Dam, with the latest predictions on the right side.  The forecast is only slightly below normal (green line).    The water supply on the river looks quite adequate this summer.

The Columbia River is in good shape because precipitation over southern BC was near normal this year, and the snowpack in the Columbia headwaters is near normal (see below)

Also encouraging is the substantial precipitation predicted through July 4  over western Canada (see below).

As I have suggested in earlier blogs, there is little reason to talk about drought over the Pacific Northwest this year.

Grass Fires in Eastern Washington: Strong Winds and Human Ignition

June is the beginning of the grass wildfire season over the lowlands of eastern Washington.

By June, the extensive grass and range vegetation of the Columbia Basin has dried out and "seasoned" sufficiently to burn.  Also in June, strong westerly (from the west) winds can develop as weak Pacific weather systems move through.

Dry range vegetation, strong winds, and an ignition source are the ingredients for a large, fast-spreading fire. 

All of this has happened over the past few days, producing several significant grass and range fires, including the one at Juniper Dunes (13,000 acres!).   

The map below shows some of the recent fires.

Here is a satellite image of the Juniper Dune fire from two days ago.   Pretty impressive looking.

The grass fires are now history, but you can see the burned (brown) areas in today's visible satellite image.

So why the fires?  

The fuel moisture of small dead fuels was under 11% and thus flammable (see below).

Looking at the 100-hr dead fuel moisture (for larger dead debris) over the Columbia Basin (below), shows that fuel moisture (solid red line) dropped below normal with our short heat wave (the gray band shows the normal range of fuel moisture).  

Light dead fuels, such as grasses and small-diameter debris, can dry out within hours under the right conditions.

And then there are the winds resulting from the passage of a weak trough aloft.  To illustrate, here are the gusts yesterday---at several locations they exceeded 50 mph!

The strong winds are critical for the rapid expansion of such prairie fires.

It appears that these fires were initiated by careless humans, which is true of most eastern Washington grass fires.