'Pineapple Express' storm for the weekend to bring heavy rains, potential flooding
SEATTLE -- What's already been a wet week in Seattle is expected to get even wetter this weekend as a potent "Pineapple Express" type storm is likely on the way.
The weather will remain showery for the rest of this week, with heavier rains returning on Saturday. Rain intensity will increase Saturday night into Sunday as a warm fetch of tropical moisture arrives from around Hawaii.
Initial forecasts suggests about 7-12 inches of rain will fall over the weekend in the Olympic Mountains and about 4-8 inches in the Cascades with snow levels around 5,500 feet. That could be enough rain to start driving some rivers over their flood banks. It's a bit early for Flood Watches yet but the National Weather Service in Seattle has issued a Hydrologic Outlook warning of the potential danger.
In the lowlands, as much as 1-4 inches of rain could fall on top of this week's soggy weather that had Seattle already reaching their monthly rain average. That could be enough to send urban streams to flood, plus ponding on roads. Forecast charts suggest about 2.5-3.0 inches are possible in Seattle from Saturday through Tuesday morning.
That much rain will also increase our risk of landslides. Soil conditions are already marginal for enhanced landslide risk and with that much rain incoming this weekend, the risk will grow.
Rainfall will taper off on Tuesday with a much cooler and less showery pattern expected for the rest of that week.