... Flooding threat increasing Saturday night through Monday for
northwest Oregon and southwest Washington rivers...
Strong and deep moist westerly flow will begin crossing the pacnw
coast Saturday morning. A very long fetch of moisture is stretching
across the Pacific with origins west to the South China Sea and has
above average potential to bring heavy rains to the area. As
such... this continues to give the appearance of a classic high
precipitation atmospheric river event where the deep moist flow will
spend a significant amount of time on a nearly perpendicular course
against the Coast Range with the Cascades taking a bit higher of the
impact. Latest forecasts for Friday night through Monday afternoon
bring 8 to 12 inches of rain to the Cascades and foothills... 7 to
11 inches for the Coast Range... 5 to 7 inches along the immediate
coast... and 3 to 4 inches along the I-5 corridor.
Given latest data... it appears multiple Coast Range rivers have a
moderate potential of exceeding flood stage. Additionally... this
event has sufficient depth to bring significant rains to the north
Oregon and South Washington Cascades where rivers will also see
potential for notable flooding.
Keep in mind that details will always be in flux under these
scenarios as subtle north or south shifts cold make dramatic
differences in which basins receive extended periods of moderate to
heavy rain. Please continue to follow the latest forecasts and
impacts as conditions warrant.
Stay up to date with the latest NWS forecasts at
weather.Gov/Portland or Mobile.Weather.Gov
River forecasts are available on our web Page at
http://water.Weather.Gov/ahps2/index.Php?Wfo=pqr (all lower case)