We have some fairly unstable air over us....meaning that with a little lift, convection (including thunderstorms) can form. And we had the lift in the form of a weak upper level disturbance (a short wave trough) moving through this AM. The images from the UW cam showed the development of the convection (the images run from around 5:30 AM to 9:30 AM.
Most of this convection was high-based and only light rain reached the surface. Here is a wonderful picture from local meteorologist Mark Stoelinga that beautifully illustrated the mid-level bases of the thunderstorm and the evaporating rain falling out of it:
You can see the convection in the latest visible image (11 AM). Most impressive storms are over the Cascades. You can also see low stratus along the coast.
The latest NWS/NOAA HRRR (high-resolution rapid refresh) forecast suggests that the southern/central Puget Sound convection should now be dying off....so SeaFair fun should be fine after 1-2 PM.
Yesterday afternoon we had a REAL thunderstorm over the central Cascades that reached 45,000 ft--unusual for our region, which usually experiences wimpy thunderstorms.
Here is the visible satellite picture at 4 PM Friday and the radar echo top product a half-hour earlier from the Camano Is radar. You see the yellow color--45K feet or higher!
As noted in my earlier blogs, there is a lot of potential for lightning-initiated fires with this short wave passage. Here is the lightning strikes for a half-hour ending 10 AM...the central Cascades are getting lit up.
Update: Some of the lightning appears to have taken out power to several thousand Seattle City Light Customers. Here is the 1 PM map: