Statement as of 10:38 AM PDT on September 14, 2013 ... A vigorous low pressure system will bring showers and scattered thunderstorms to western Washington Sunday into Sunday night... A big change to the western Washington weather pattern will unfold Sunday. Low pressure off the Oregon coast Sunday morning will lift northward bringing a change to unsettled weather across western Washington. A strong marine push is expected ahead of this system around late morning or midday Sunday producing a burst of breezy southwesterly winds. Securing loose items like garbage cans and patio furniture is recommended. Those on the water in watercraft should be especially cautious of the rapid onset of winds. The air mass aloft will become unstable during the day Sunday. Monsoon moisture over the northern Great Basin will also be pulled into the Pacific northwest. This combination will result in widespread showers and scattered thunderstorms. General rainfall amounts from noon Sunday through midnight Sunday night will range from a quarter to a half inch across the area. However... some thunderstorms could produce locally heavy rain amounts over an inch in a short period of time. This could result in localized ponding of water on roadways and may overwhelm drainage systems. Monitor the latest forecast and statements from the National Weather Service. The latest information can be found on www.Weather.Gov/Seattle/ ... listening to NOAA Weather Radio and National Weather Service social media.