What is happening now is really amazing. The atmosphere above us has warmed substantially during the past 24-h. Seattle is 5F warmer than it was a day ago and the air aloft (measured by the Sand Point profiler) is about 6F warmer. The minimum temperatures this morning are considerable warmer this morning compared to yesterday morning. Clearly, today will be substantially warmer and SEA-TAC will get close to 100F today. Some warmer Puget Sound locations will get to the century mark. And remember, the Willamette Valley got to 100F yesterday...although they have done that many times (they don't have the cooling influence of the water that the Puget Sound region enjoys. My book has a section on the heat of the Willamette Valley and the major temp records around here)
We way well break another major record....the high low temperature record...which until now has been 69F. Will know in a few hours whether that record is gone.
Probcast is still going for over 100F tomorrow...and Thursday as well.
One unusual aspect of this heat wave...and something that has made it feel much worse....is the humidity. Dewpoints are very high for around here...generally in the 60sF and in some places close to 70F. Feels like an east coast summer. Dewpoint is a good measure of the amount of moisture in the air (much better than relative humidity which varies during the day as temperature changes). More moisture in the air makes us feel warmer by lessening our ability to evaporate water from our skin (sweat) and the moisture partially blocks the infrared radiation leaving the surface....thereby keeping the temperatures up.
Anyway, this is a very serious weather event, and the National Weather Service has upped their predictions to the century mark. People don't think about heat waves in the same vain as storms, but heat kills more people around the world. So drink lots of liquids and check on the elderly, who are particularly vulnerable. Another risk is for kids in sports camps, where heat prostration can strike even the young. I am going to bike to work as usual, but will go early and my route is in the trees.