Puget Sound Convergence Zone Puget Sound Convergence Zone The Puget Sound Convergence Zone (PSCZ) is a meteorological phenomenon that occurs over Puget Sound in the U.S. state of Washington. It is formed when the large-scale air flow splits around the Olympic Mountains and then converges over Puget Sound. This convergence zone generally occurs between north Seattle and Everett and can cause updrafts and convection, which leads to a narrow band of precipitation. A second, weaker convergence zone can occur between approximately Victoria, British Columbia, and Bellingham, Washington, over the San Juan Islands, as a result of southwesterly air blowing from the Strait of Juan
Puget Sound Central Basin. Puget Sound's sills, a kind of submarine terminal moraine, separate the basins from one another, and Puget Sound from the Strait of Juan de Fuca. Three sills are particularly significant—the one at Admiralty Inlet which checks the flow of water between the Strait of Juan de Fuca and Puget Sound, the one at the entrance to Hood Canal (about below the surface), and the one at the Tacoma Narrows (about ). Other sills that present less of a barrier include the ones at Blake Island, Agate Pass, Rich Passage, and Hammersley Inlet. The depth of the basins is