Seattle Weather Anomolies

Puget Sound Convergence Zone (PCSZ)

- Airflow passes around the Olympic Mountains to the west and merges over the Puget Sound before passing the Cascade Mountain Range to the east. The convergence of airflow results in localized weather cells, often in stable atmospheric conditions. The convergence zone is often no more than 10 Km deep and results in interesting instrument flying. Since this occurs in stable air, it is relatively safe. Occasionally the PCSZ can be seen on the SCN traffic cam series.

Effects related to the PSCZ

- I have seen on several occasions where a cloud layer follows a 3 degree slope along the KSEA glideslope over BFI, on the south side of Seattle (at Boeing Field). Other times, downtown Seattle will have rain, while partly cloudy conditions exist north and south of the city.

Rain Forest

- The region to the west of Seattle, which is the Olympic Penninsula, is a temperate rain forest, as are parts of British Columbia and the north coast of Oregon.

AIRMETs and SIGMETs

If some of the terminology seems arcane, that's because this webpage is from an aviation site. For example most pilots know that the broadcast media often call airport pilot advisory recordings to get conditions at different locations.

The "sun breaks" expression is a favorite of local wx-announcers. Fortunately, we don't hear them refer to "partly sunny" skys unless they really haven't the foggiest idea of a forecast. But then, why would any credible forecaster use non-weather terms like "partly sunny" unless he/she doesn't have the information? Some moron at KUOW sometimes pulls that "partly sunny" stunt. At night, is it "partly mooney" or "partly dark"?