Looking at the hourly data at Sea-Tac Airport, it appears that we have broken the record for highest minimum temperature in Seattle history. It was 69F and so far today the airport has only dropped to 71F, and it has subsequently rise...so that is probably it. This is a major record to break. At 9 AM Sea-Tac is 88F, 10F ahead of yesterday (due to the downslope flow). We are probably going to break the all-time record high--will be hard to stop it now.
Now, what about the high temperature record--of 100F. Yesterday probcast was giving the most probable maximum for the airport of 101F (by the way, so many of you have hit the site that it appears to be unavailable now--there is a major power failure on campus, probably heat related, and the building with the computer server is affected). If we do this, it will be close.
The sand point profiler and surface observations indicates that temps are warmer the lowest thousand feet or so, but slightly cooler air has moved in aloft (see figure, time in UTC, 2912 is 5 AM, heights on left in meters, red lines are temps in C). This air is associated with southeasterly flow that has developed aloft. This was forecast yesterday--high pressure building in east of the mountains has reversed the east-west pressure gradient, producing offshore and downslope flow. Downslope flow produces compressional warming and works against the cooling northerlies that often develop in the afternoon over the central Sound. But cooler air aloft obviously works against it. The models and probcast suggest the balance will be towards warming today. Below is the latest night's high resolution (4-km, WRF model) run for this afternoon at 5 PM, showing temperatures at 2 meters (surface temps). Note the zone of above 100F than includes Sea-Tac.
The Willamette Valley is much hotter--several locations will get to 105F. Their lack of proximity to water makes that area an oven in these situations and they are often 5-15F warmer than the Puget Sound region.
Anyway, more later...this is going to be close.