Wednesday, June 23, 2010
Finally! The 75F Ceiling is Broken
Today, temperature at Seattle Tacoma Airport has reached the the magic number--75F-- in fact later this afternoon temperature climbed to 77F. This is the latest into the summer season that Sea Tac has reached 75F for the first time. As apparent in the high resolution visible satellite image below--a clear zone existed today over western Oregon and Washington. Offshore extensive low-level cloudiness was in place, while eastern Washington was generally cloud with some convective showers over the northern portions.
Significant pressure changes have occurred during the past several hours, with the onshore pressure gradient reversing: pressure is now higher on the coast than inland, and some cooler ocean air will move in. Tomorrow will not only be cooler, but there will be considerable clouds and some light showers over the region.
I have gotten a large number of comments suggesting that the Iceland volcano has been the cause for our cool weather. Let me be absolutely clear on this...there is no reason to think this is true. None. The continuing eruption is NOT putting large amounts of sulfuric acid aerosol into the stratosphere---which is the only way that volcanic eruptions can have climatic impacts. Remember--Mt. St. Helens had virtually no climatic signal for the same reason.
Posted by Cliff Mass at 8:34 PM