× Hydrologic Outlook
Until 2024-11-18T14:00:00-08:00 • National Weather Service
ESFPQR A series of storms will bring ample precipitation to Northwest Oregon and Southwest Washington this week. Of particular concern is the potential for heavy rain Tuesday night through Friday morning, which could result in some flooding for area creeks and rivers. The latest projections of the most likely amounts for storm total precipitation are a little lower today than yesterday's forecasts. Amounts range from 3.5 to 6 inches for the Coast, Coast Range, and Cascades, with 1.5 to 3 inches for inland valley locations, including Portland, Salem, and Eugene. Upper end projections, with about a 10 percent chance of occurring, range from 6 to 10 inches for the Coast, Coast Range, and Cascades, and 2.5 to 3.5 inches for inland valleys. Snowmelt in the Cascades from 2000 to 4000 feet elevation could add runoff, although runoff from heavy rain would be the main driver for any flooding that occurs. Rivers will rise starting Wednesday. Small streams and fast-responding rivers could see flooding as early as Wednesday night or Thursday, with slow-responding rivers potentially flooding by this weekend. Heavy rainfall will also cause water ponding in low lying areas and other areas of poor drainage. Monitor weather.gov/portland for the latest updates and any watches, warnings, or advisories that may be issued for this event.