October 26, 2018

Unusually Dry Pacific Northwest on Track to See Much-Needed Rainfall, But Not Enough

We don't really get the chance to talk about rain out west these days. A recurring story across much of the past...well, several years...is that the west is thirsty for any drop of water it can wring from the sky while areas east of the Rocky Mountains have more rain than they can handle. Fortunately, the Pacific Northwest is in the midst of a much-needed rainy spell, but the region is also grappling with a hefty rainfall deficit, and it'll take more than a couple of days of rain to make a dent in the region's drought.

NOAA's latest precipitation analysis really tells the tale of this year's weather patterns. The above map shows the departure from normal precipitation since January 1. The departure from normal is measured in inches. Vast swaths of land east of the Rockies have seen feet more rain than they typically see through the end of October—isolated pockets of North Carolina have seen more than 100" of rain this year—while the West Coast between northern California and Washington stands out for having fallen more than a foot below normal in rainfall so far this year.

Thursday's update of the U.S. Drought Monitor shows drought conditions overspreading almost everyone along and west of the Continental Divide. The very worst drought conditions exist over the Four Corners region, but parts of the Pacific Northwest—especially in Oregon—continue to slip into deeper levels of drought. Conditions have actually improved somewhat in northwestern Washington, where some areas have managed to escape drought over the past month or so.

We have the chance to erase some of those rainfall deficits over the next couple of days. Several rounds of rain will move ashore in the Pacific Northwest through early next week, bringing a general swath of 3-5" of rain to western Washington. The highest totals will fall in the mountains, where the highest elevations will see some precip fall as snow, while the Weather Prediction Center predicts about 3" of rain around the Puget Sound in the coming days.

Long-range models continue to show waves of rain moving across western Washington over the next week or so. While this will help erase some of that steep precipitation deficit in some areas, it won't do much to ameliorate the worsening drought in Oregon. The Climate Prediction Center's latest precipitation forecast for the next three months shows heightened chances of below-average rainfall in interior parts of Washington and Oregon, while equal chances for above- or below-normal precipitation exist along the coast.

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I graduated from the University of South Alabama in 2014 with a degree in political science and a minor in meteorology. I contribute to The Weather Network as a digital writer, and I've written for Forbes, the Washington Post's Capital Weather Gang, Popular Science, Mental Floss, and Gawker's The Vane. My latest book, The Skies Above, is now available. My first book, The Extreme Weather Survival Manual, arrived in October 2015.