URGENT – IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service Portland OR
529 AM PST Fri Dec 1 2023
…FLOOD WATCH IN EFFECT THROUGH TUESDAY AFTERNOON…

* WHAT…Flooding caused by excessive rainfall is possible.

* WHERE…Portions of northwest Oregon, including the following
areas, Cascade Foothills in Lane County, Central Coast Range of
Western Oregon, Central Oregon Coast, Central Willamette Valley,
Coast Range of Northwest Oregon, Greater Portland Metro Area,
Lower Columbia, North Oregon Coast, Northern Oregon Cascade
Foothills and South Willamette Valley and southwest Washington,
including the following areas, Greater Vancouver Area, I-5
Corridor in Cowlitz County, South Washington Cascade Foothills,
South Washington Coast and Willapa Hills.

* WHEN…Through Tuesday afternoon.

* IMPACTS…Excessive runoff may result in flooding of rivers,
creeks, streams, and other low-lying and flood-prone locations.
Creeks and streams may rise out of their banks. Flooding may occur
in poor drainage and urban areas.

* ADDITIONAL DETAILS…
– A series of atmospheric rivers will bring periods of
widespread heavy rain through early next week. Cascade snow
accumulations through Saturday morning will experience heavy
rain Saturday night into Sunday morning which will contribute
to excessive run off. Total rain amounts for the entire
weekend range between 3.0-5.0 inches along the coast, 4.5-6.5
inches over the Willapa Hills and Oregon Coast Range, and 3-4
inches across the interior lowlands, with 4.0-7.0 inches of
rain expected over the Cascades, Cascade foothills, and
western Columbia River Gorge. 2.5-3.5 inches of rain is
expected for central Columbia River Gorge and Upper Hood
River Valley. Localized heavy rain will lead to higher rain
totals.
– http://www.weather.gov/safety/flood

PRECAUTIONARY/PREPAREDNESS ACTIONS…

You should monitor later forecasts and be alert for possible Flood
Warnings. Those living in areas prone to flooding should be prepared
to take action should flooding develop. Given the aforementioned
rainfall amounts expected this weekend, river levels will be rising
quickly. Most rivers have anywhere from a 30-50% chance of reaching
at least minor flood stage, except the mainstem Columbia and
Willamette Rivers which is less than 10% chance. Coastal rivers
however have a 40-60% chance of reaching minor flood stage and
20-30% chance for reaching major.