How Unusual Has This Winter Been?

It is now officially spring, and a good time to check on how unusual this winter has been. 

Meteorologists often do so by reviewing conditions over the water year (October-now), and I will do the same.

 First, consider Seattle's accumulated precipitation during the present water year (green line, observed; red line, climatological average).  

We have been a bit above normal overall!   Wet periods in December and March.

Yakima, on the east,  is similar, with a water year total near normal.  There is a reason I have been discouraging the drought talk.

Temperature?  See below, with blue being observed, tan showing the normal range, and red/light below showing the record highs and lows.

At Seattle, temperatures have been unremarkable, with periods of above and below normal warmth.  No records broken.

At Yakima, there is a clear warm bias this year, particularly in December and recently.  

These two warm periods are the reason the snowpack is now below normal for the Yakima Basin, but why the reservoirs are well above normal in water stored.    

I know some folks are interested in climate change, so what do the long-term trends for water year temperatures and precipitation look like? (October through February shown below)

Consider the situation for Western Washington from 1896 to the present.

For temperature, this year was warmer than normal but not a record. Over the past 130 years, there has been a slow warming of roughly 1.5 F.  

A modest global warming signal.

In contrast, a slight increase in precipitation....too small to be noticeable or significant.

Because of the two warm spells, the snowpack over the region is about 60% of normal (see below).   

Let me stress, this is mainly about the warm/wet periods associated with atmospheric rivers and Kona Storms, NOT global warming, as being claimed by some media and amateur YouTube channels. 

The Revenge of Kona Hits BOTH Hawaii and Washington State

 There has always been a close connection between Hawaii and Washington, and that relationship was on display over the past few days.

Kona does not kid around

A strong Kona storm, with powerful, southwesterly flow, rammed into the Hawaiian Islands, producing intense rainfall.   Check out the totals over the past 48 h  around Oahu (below)

Many locations received more than 10 inches, with some reaching as high as 20 inches.   Major flooding has resulted.

This moisture continued toward the Pacific Northwest (see the total atmospheric moisture from yesterday morning below).   As you know, these moisture plumes are also called atmospheric rivers.

When that moisture reached our region, it was forced to rise on our terrain, resulting in heavy precipitation.  To see how much...check out the 72 hr totals shown below.   

Wow.  Several locations received over 6 inches,

As a result, several of our rivers are at major flood stage, with the National Weather Service issuing serious flood warnings on BOTH sides of the Cascades.

The NOAA River Forecast Center is predicting serious flooding on many local rivers (see below).

For example, the Snoqualmie River near Carnation is now at major flood stage (see below), something that is unusual this late in the season.

According to the U.S. Drought Monitor, much of the heavy rain/flooding area is "abnormally dry."     I have some colorful language to describe their analysis, but this is a family-friendly blog.   I will Kona deal with them 😁