The latest statistics on energy production in the Northwest are available from the Bonneville Power Administration, and they are troubling:Wind power generation (green line) has collapsed over the past few days (see below). Spring is usually a time when wind output increases sharply, but not this year.
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What’s happening?
Something happened between March 25 and March 27. But what?
Wind is driven by pressure differences, so consider changes in the regional pressure field.
At 5 p.m. on March 25, there was high pressure offshore and low pressure over eastern Washington, resulting in a westerly flow (from the west) over eastern Washington (see pressure map below ). Good for generating wind power.
A look at winds at 5 p.m. on March 25 (below, with gusts in red), shows strong winds (greater than 20 knots) across many of the major wind generating areas in eastern Washington and Oregon.
But the pressure situation at 5pm on the 27th was completely different, with a strong offshore low pressure (see below).
This significantly weakens the pressure difference between the Cascades and therefore weakens the winds. To see this clearly, here is the zonal wind at 5pm on the 27th. Can you see the difference?
This winter we have repeatedly fallen into low pressure areas off the coast. As noted in my previous blogs, This is a classic situation during El Nino years, this is shown by a composite analysis of the pressure difference from normal during El Niño years (see below, from the NOAA website). Blue indicates increased low pressure offshore.
For those hoping wind power will lead the way to independence from other energy sources, This situation is a warning.Wind power alone cannot fill the gap: it is too variable, both by season and by weather regimes.
