How Bad Was May? Could June Be A Continuation?

 May 2022 will go down as one of the wettest and coolest in Northwest history, setting the stage for a delay in the regional wildfire season.

To provide some perspective, here are the lower atmosphere temperature differences from normal (°C) for the month, courtesy of Dr. John Christy of the University of Alabama in Huntsville.    A cold bullseye is apparent over the Pacific Northwest (medium blue colors, more than 1.5C below normal).  Only one place is colder:  eastern Russian (I could make a comment here, but won't).

The eastern U.S. was warmer than normal in May. The yin and yang of weather.

The snowpack over our region is amazingly deep (see below).  For example, the snowpack on the southeastern side of the WA Cascades is EIGHTEEN HUNDRED FIFTY percent of normal.   Yes, 18 times normal.  The snowpack east of central Puget Sound is 319% of normal.   Just crazy.

And if that does not impress you, Seattle had its wettest May since 1948 (see below).   You will notice there is little long-term trend in Seattle precipitation.

The entire region was frigid during the past month, with temperatures over much of the Northwest averaging 4-6F below normal for the month.   The cold extends eastward to Idaho, Montana, and Wyoming....and beyond.

Why so cold and wet?  

Because of a persistent trough of low pressure than has been hanging around over the region.  

To illustrate, below is a map of the difference from normal (the anomaly) of heights at the 500 hPa pressure level (you can think of it as the difference from normal of the pressures at 18, 000 ft) for the past 30 days  Blue and purple indicate much lower than normal pressures/heights-- called a trough.

A very large, strong trough is over our region--and that produces cool/moist conditions.  In contrast, there is ridging...higher than normal heights and pressures-- over the eastern U.S. where temperatures are above normal.   There is a very wavelike pattern of alternating low and high pressure.  Not an unusual pattern.

Now the depressing part.

The latest model runs suggest June is going to continue the cool/wet regime.  Sorry.

For example, the latest UW model forecast for the accumulated precipitation over the next week shows bountiful rain over the region, with many of the mountain areas getting more than 2 inches.  That is a lot for June.   Even northern CA gets a piece of the wet action.

And the temperatures are predicted to be substantially cooler than normal over the next week (see European Center ensemble forecast for temperature difference from normal below).  The entire Northwest will be cooler than typical (blue colors).

It appears that the old adage about Northwest weather will be true this year:  Northwest summers start on July 12th. Only a month and a half away!