A Dry May and a Warm Weekend Ahead

May was a relatively dry month for much of the Northwest, with the area getting about 65% of normal precipitation.  Not the driest May on record by any means, but drier than normal at most locations.

The climatological average rainfall for May over the Northwest is shown below.  About 2 inches over the western lowlands and 3-6 inches over the mountains.  Less than an inch over much of the Columbia Basin.

Here is what actually fell. Yes, we got some rain, but clearly less than normal...about a half inch less than normal over Puget Sound and even drier over the Willamette Valley.   Some decent totals in the mountains.

Looking at Seattle for May (green, this year, brown line, normal), precipitation was about half of normal. Felt like a dry month.

Hoquiam was about three-quarters of normal (below).  Bellingham (not shown) was similar.

In contrast, the Tri-Cities were wetter than normal.

Even with a drier than normal May, western Washington reservoirs are in good shape.  Seattle, for example, has normal storage at this time.

The latest forecasts predict generally dry conditions over the next week, except southeast Oregon (see total precipitation forecast below).  The reason:  a big ridge of high pressure over our region.

Warm Temperatures Ahead

This weekend, a ridge of high pressure will develop aloft over our area (see the upper-level map for 11 AM Saturday).  And it is going to hang around for several days.

As a result, temperatures will soar into the mid-80s on Sunday and Monday, as illustrated by the forecast temperatures at Seattle below:

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The next serious rain?  The latest forecasts suggest on June 17th!

Announcement

I will hold a special online Zoom session at 10 AM on Saturday for Patreon supporters.  Will talk about the summer outlook, hurricane outlook, and more.  And spend plenty of time answering your questions.