Monday night update: the TLDR is, rain and breezy winds will continue...though we'll get a brief break tomorrow.
Even though we were in the rain shadow midday, we're over an inch of rain since this afternoon. We'll get a brief break overnight tonight thru tomorrow, as the rain sags south and takes aim at southern Washington / northern Oregon...but it doesn't last long, as it'll move northward tomorrow evening thru Wednesday. The Wind Advisory expires tonight at 10pm - shouldn't be as windy the next couple days, but still will be breezy. Rain will taper off by Thursday, leaving us with showers to end the week...but we need to get through the next few days first.
As for flooding...area rivers and creeks are expected to get to flood stage. (I'll drop a few links in the comments, and I've attached a couple pics here too.) Issaquah Creek is expected to crest in "Action" stage late Wednesday night / early Thursday morning, while the Snoqualmie River is forecasted to reach Major Flood stage tomorrow thru Thursday night.
Forecast over...a little educational tidbit right now. You've probably heard the term "Atmospheric River" being used to describe this event - it's not a new phrase, it's actually a meteorological term that's been around for a long time. It describes a very long, relatively narrow stream of moisture in the atmosphere that transports tremendous amounts of water vapor - that's why I've sometimes called these a "fire hose" of moisture! Looking at the satellite view, this one has its origins well west of Hawaii, thousands of miles away. They're also concentrated in the lower atmosphere, typically within the first mile or two above the surface. When this moisture plume hits mountains and is forced upward, the air cools and wrings out the moisture like a sponge...which results in moderate to heavy rainfall for long periods of time - but also the rain-shadowing on the backside of the Olympics (and Cascades). They aren't inherently bad - they can actually be very beneficial, and are crucial for building our water supplies...but they can cause problems when they last for a long time, or bring more moisture than the ground can handle - besides flooding, overly-saturated ground can cause downed trees and mudslides. This event is one of the stronger ones we've had in the past few years.