The Puget Sound Convergence Zone is an important feature of Seattle's weather. In the convergence zone, air arriving from the north meets air flowing in from the south. Both streams of air originate over the Pacific Ocean; airflow is split by the Olympic Mountains to Seattle's west, then reunited to the east. When the air currents meet, they are forced upward, resulting in convection. Thunderstorms caused by this activity are usually weak and can occur north and south of town, but Seattle itself rarely receives more than occasional thunder and small hail showers. The Hanukkah Eve Wind Storm in December 2006 is an exception that brought heavy rain and winds gusting up to 69 mph (111 km/h), an event that was not caused by the Puget Sound Convergence Zone and was widespread across the Pacific Northwest. COUNT 5
QSN1 What is a very significant part of Seattle's weather system? ANS1 Puget Sound Convergence Zone QSN2 Of what is the Convergence Zone comprised? ANS2 streams of air QSN3 From where do the two streams of air come? ANS3 Pacific Ocean QSN4 What mountain Range splits the wind stream in the west of Seattle? ANS4 Olympic Mountains QSN5 What bad wind and rain event was not caused by the Convergence Zone? ANS5 Hanukkah Eve Wind Storm