First Major Convergence Zone of the "Fall"

Today was a wet day around Puget Sound, with some locations getting as much rain in the last12 hr as all of July and August.  The reason?  An upper trough passage with a strong Puget Sound Convergence Zone.  There was torrential rain, lightning and thunder, and even a report of funnel cloud.

 Here is the 12 hour total ending 7 PM Friday for rainfall from Seattle Rainwatch.  A huge gradient of rain from virtually nothing over the south Sound to as much as 2-4 inches within a southwest-northeast band.

This band was mainly associated with our local favorite weather feature, the Puget Sound Convergence Zone, which is produced by converging airstreams over Puget Sound.  Converging air causes upward motion...and with relatively unstable air aloft...lots of convection and thunderstorms.  You could view the convergence zone in action from this radar image around 3 PM.  You see the band over Puget Sound?  Red colors are pouring rain or hail.

During the same period, the lightning detection network showed similarly oriented lightning activity.

The SpaceNeedle Cam got a good luck at the scary looking cumulonimbus clouds associated with the convergence zone.  Here is at image around 3 PM looking north.  You can see the precipitation falling out of the clouds.

A visible satellite image around 2:30 PM shows the convergence zone and the characteristic dry zones to the north and south (caused by air sinking off the Olympics and Vancouver Is. mountains.)

The western slopes of the Cascades and Olympics also received plenty of rain today as shown by the 24 rainfall totals ending 8 PM Friday.  A few favored locations (east of Monroe) got washed away with 2-3 inches.

The summer drought is over..... we will miss it.

Announcement: My Climate Surprise Talk on September 28.

During the evening of September 28, I will be giving a talk in Seattle at UW's Kane Hall on Climate Surprise: Unexpected Impacts of Global Warming on the Pacific Northwest.   You think global warming will simply bring warmer temperatures, drought,  less snow, and more storms?  Think again. The latest climate model simulations provide a far more nuanced prediction of what will happen here, with some of the results quite surprising.   This talk is sponsored by CarbonWa and the Audubon Society To find out more or to secure tickets, please go here.