May 31, 2023

Wind Speed "Hot Spots' In Eastern Washington Produced by Gaps in the Cascades

This has been a very windy period over portions of eastern Washington due to a large pressure difference across the Cascades (higher pressure to the west, lower pressure to the east).

The maximum winds today since midnight  (see below) reached 51 mph near Ellensburg.  Winds were mainly strong near and downstream of Ellensburg and east of the eastern terminus of the Columbia River gorge.

A model forecast for this afternoon shows the two main wind plumes over eastern Washington.  One east of Cle Elum and Ellensburg and the other downstream of the Columbia Gorge (stronger winds shown by the blue and greenish colors).

So why are the strong winds in eastern Washington localized?

It has to do with the variable height of the Cascades and specifically two lower areas in the north-south barrier.  Below is a terrain map for Washington and northern Oregon, with the green colors representing lower elevations.  Note there are two lower regions across the Cascades:  a near-sea-level Columbia Gorge between Oregon and Washington, and the "Stampede Gap" region of the central Cascades (with lowest elevations around 3000 ft), which also includes Snoqualmie Pass.

 Both are indicated by red arrows.

When a large pressure develops across the Cascades, with higher pressure to the west and lower pressures to the east, winds surge through these gaps, creating two major westerly wind swaths over eastern Washington.  A minor wind swath can also be produced downstream (east) of Stevens Pass.

The winds exiting these Cascade gaps strengthen during the evening after the daytime heating in eastern Washington causes the pressure to fall there (and thus increasing the pressure difference across the Cascades0. To illustrate, below are the winds forecast for this evening (in mph)...a lot more greens in eastern Washington, which means stronger winds.

With cool/high pressure to the west of the Cascade crest the last few days, the pressure pattern has been very favorable for consistent westerly winds over the wind turbines of eastern Washington, producing consistently high wind energy availability (see the Bonneville statistics below, wind plus solar shown by the green line).

As noted in my earlier blog, the total of wind and solar is roughly one-third of the demand
 (red line).  Hydro generation (blue line) has been allowed to decline because of the bountiful wind energy.

The latest forecasts suggest the west side will warm and wind energy will thus decline substantially over the next few days.

May 29, 2023

Unusually Cool Weather in the West Means Lots of Wind Energy in the East

 This is a good time to charge up your electric car...particularly during the evenings.

The reason?  

Unusually cool weather is forecast for the next few days in western Washington and Oregon.  Seattle will be firmly into cool, marine air the next few days, with highs only reaching the LOWER 60s.

In contrast, it will remain warm over the Columbia Basin, with 80s for the first part of the week, climbing into the 90s by week's end.

This pattern is very favorable for producing healthy westerly winds along the eastern slopes of the Cascades and across the wind farms east of the Cascade crest.

Taken by Jeffrey Katz

The sea level pressure (solid lines), surface winds, and low-level temperature (colors) forecast for 2 PM Tuesday (below) show the story.  High pressure and cool temperatures (green) offshore, warmer temperatures (orange and red colors) east of the Cascade Crest.  You will notice a large pressure difference across the Cascades, which will produce strong winds over the east of the barrier.

A similar, but attenuated, version of this situation was in place today (Monday) and winds were gusting to 30-40 mph around Ellenburg and other eastern slope locations (see max gusts on Monday below).

Even stronger winds will occur on Tuesday and Wednesday.    The result will be lots of wind energy generation.  The Bonneville Power summary shows increasing wind generation the past few days (green line)...getting to roughly one-third of demand (red line).   Will do even better tomorrow and Wednesday.

Wind energy generation in our region is unfortunately out of phase with demand.  When we have mild temperatures--and little need for AC-- there is lots of wind energy.  But when we really cook, wind energy is quite small since the westerly winds are absent then.

The cool temperatures in the west won't last forever.  The latest forecast suggests that we will warm up to near-perfect temperatures in western Washington by next weekend.

And relatively toasty (upper 90s) over the Columbia Basin

Wind Speed "Hot Spots' In Eastern Washington Produced by Gaps in the Cascades

This has been a very windy period over portions of eastern Washington due to a large pressure difference across the Cascades (higher pressur...