This is a good example of over-warning...something that does happen occasionally. Why does it occur? Well sometimes it is due to faulty forecasts...not the case this time. Other times there is a tendency to try to cover a low-probability dangerous situation...better safe than sorry kind of philosophy. And then there are the psychological elements. Perhaps meteorologists are the last people you want forecasting the weather, because many of us love severe weather and subconsciously want it to happen. When you want something to happen....well you can guess the result. And lets face it...when one goes for a severe forecast, the media takes notice...another positive feedback for some. When I give my forecasting class I tell students they have to think like Spock or Data of Star Trek...put the emotions aside..put this is more easily said then done. Anyway, meteorologists are human and you have to factor that in. Certainlywe are no worst than economists...and I think you can argue that our track record is a lot better. I mean A LOT better.
How can you get into the head of a meteorologist to decide whether you believe their forecast? Well, for me you have this blog and my Friday 9:50 AM segment on KUOW. For the NWS, they have very useful forecast discussions...something a few of you mentioned in the comments. The lead NWS forecaster on each shift pens a description of what she or he thinks is happening and will happen and why. A great product. The only issue is that there is often some technical jargon in there (like CWA--Coordinated Warning Area--and some weather terminology you might not be familiar with like 1000-850 mb thickness). But 50-75% should be understandable. The forecasters also identify themselves and if you read them frequently enough you learn about their "quirks." (I won't say any more or will certainly get into trouble) You can find the forecast discussion on the web....for the Seattle office: http://www.wrh.noaa.gov/sew/get.php?wfo=sew&pil=AFD&sid=SEW
I find it useful to read the discussions of neighboring offices (e.g., Portland) as well.
There are other useful discussions to look at. The Northwest Avalanche Center does a mountain weather forecast and discussion...and these individuals are very skillful and knowledgeable about mountain weather: http://www.nwac.us/forecasts.htm
Scott Sistek of KOMO TV--a past UW Atmos graduate and the chief behind the scenes weather staffer at that station--has a wonderful weather blog (http://www.komonews.com/weather/blog). Great information from a very insightful guy. King5 weathercasters also do blogs and some of them have substantial backgrounds (Jeff Renner, Sharon O'Donnell, and Rich Marriott all have professional degrees in the field).
And of course you can watch the TV weather broadcasts--where you often hear some of the logic and uncertainty underlying the forecast.
In any case, there is valuable information regarding the confidence and nature of the forecast that you can glean from the above sources. It pays to be an intelligent consumer of weather information.
PS: A great example of a Puget Sound convergence zone on the latest radar:
