Flood Potential Outlook
Issued by NWS Portland, OR

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FGUS76 KPQR 192221

Hydrologic Outlook
National Weather Service Portland OR
321 PM PDT Thu Oct 19 2017


Heavy rain appears likely this weekend across southwest Washington
and northwest Oregon, as a warm front lifts northeast across
Oregon and stalls near the Washington border. Meanwhile, a strong
and moist Pacific jet stream will run parallel to this front,
resulting in areas of heavy rainfall across the Pacific Northwest.

While some details remain uncertain, forecast models are showing
fairly good agreement in placing the heaviest rain from this event
in the higher terrain of southwest Washington and far northwest
Oregon. These areas stand to see 4 to 8 inches of rain this
weekend, though this precipitation may start out as snow in the
higher elevations of the Cascades. Coastal areas of southwest
Washington and far northern Oregon are expected to receive 3 to 6
inches of rain this weekend. Meanwhile, the Willamette Valley and
Lane County will generally receive 1 to 3 inches of rain with
areas farther north in the Willamette and lower Columbia River
Valleys most likely to experience the highest rainfall totals.
These numbers may still change depending on where the frontal zone

Rainfall intensity may be enough to trigger flash flooding and debris
flows downstream of burn scars, particularly near the Eagle Creek
Fire in the Columbia River Gorge.

While significant rises are expected on many area rivers, mainstem
river flooding is not currently forecast at this time. Smaller
rivers such as the Grays River near Rosburg will likely be prone
to flooding as well. In addition, rainfall rates late Saturday
night and Sunday may be high enough to produce urban flooding due
to clogged storm drains.

The National Weather Service will continue to monitor the rivers
closely and issue watches and warnings if needed. People living
near southwest Washington and northwest Oregon rivers should
monitor the latest weather and river conditions for the next week.
Listen to NOAA weather radio or check weather.gov/portland for
further updates.



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