WSDOT photo of a big tree blocking parts of I5
First, what were the wind speeds like? Here is a map of the max winds during the past 24 h; virtually all of the high winds occurred this afternoon. Plenty of folks experienced gusts of 30-45 mph, with some marine locations to 50 or a bit more. Interestingly, the winds were worse over the inland waters than along the coast. Strong winds are a problem now because trees have their leaves and thus are more prone to catching the wind. Furthermore, this has been a pretty wimpy windstorm season, so there was only modest "pruning" by winter winds.
The UW WRF model forecast substantial winds during the afternoon (gusts reaching 25-35 kt, see below), although it did underplay them by 5-10 mph in places. That is unfortunately typical.
Here is the radar image right before it hit the UW (1:20 PM). Pretty impressive line. You don't see reds (very, very heavy rain) on Northwest radar imagery very often.
Winds picked up modestly with the first band, but the REALLY strong winds followed the second band, which was not associated with much rain. Thus, this front was distributed over two steps, each associated with a rain band. Here is a plot of the weather at the UW to illustrate. The top panel shows sustained winds at gusts. The sixth panel is rainfall. A short spike of wind with the first band (around 21z), but the real winds were later (around 00z--5 PM) following the second band.