Monday, July 27, 2009
Major Heat Wave and Possible Record
Today is running 7F ahead of yesterday, which got to 89F. It is clear that temps will get into the lower to mid 90s around the region today. Our most skillful tool for predicting temps...probcast..is now forecasting 102 for sea tac on Wed...this would be the all time record for any date in any year. Above is the probcast forecast for the max temps on Wednesday (you can see it yourself at www.probcast.com. The purple colors indicate where temps should be higher than 97F). Amazingly, this heat wave could last into the weekend (although the temps should modify a bit on Friday into Sunday, but still in the 80s). And remember, it will be hotter in Portland and the Willamette Valley, where temperatures well into the 100s will occur.
The heat wave is made worse by the high dewpoints today. Many locations are in the sixties, some in the upper 60s and near 70F. Dewpoint is a measure of the absolute amount of moisture in the air..we are usually in the lower 50s in the summer. High dewpoints keep nighttime temperatures up--which makes a heat wave much worse.
In short, we are about to enter an historic heat wave for our region. One day, your grandchildren will ask you... did you really experience the temperatures of July 29th, 2009? What was it like? How did you survive it?
Posted by Cliff Mass at 11:30 AM