Spring is prime time for Puget Sound Convergence Zone
Apr 9, 2014, 9:40 PM | Updated: Apr 10, 2014, 10:28 am
The convergence zone can occur any time of the year, but the spring season is when it occurs most often. (AP)
(AP)
Spring is prime time for the Puget Sound Convergence Zone. The convergence zone can occur any time of the year, but the spring season is when it occurs most often.
What is the Puget Sound Convergence Zone? It is similar to water moving down a stream with water wrapping around a large rock in the water. The water flows around the rock and converges on the downstream side.
In the case of the atmosphere, the convergence zone occurs when westerly airflow off the Pacific Ocean, below about 7,000 feet, wraps around the Olympic Mountains, converging usually in a line across northern Kitsap Peninsula, south Whidbey Island and Snohomish County. The colliding air rises, produces clouds, rain and if cold enough, even snow. If the air mass is unstable enough, thunderstorms can occur as well.
Usually the westerly air flow is stronger down the Strait of Juan de Fuca resulting in the convergence zone drifting southward through Kitsap County and into King County. In the meantime, skies tend to have clearing to the north and south of the convergence zone.
The National Weather Service in Seattle put together a short 6-minute video about the Puget Sound Convergence Zone, great for the classroom, at work or at home.
