Rain Event Update Shows Some Improvement

By Rod Hill on 2021-11-11

Flood Watch for most of western Oregon and southwest Washington through Friday night.  Waves of steady
rain will generally push north up through Portland this morning as warm air advection continues. Heavy
rain rates at times up to .50” of rain an hour with embedded convective activity.  There were lightning strikes
near the coast last night.  Spotty thunder continues to be possible. 

(Flood Watch in dark green)

Early morning temps are near and above 50 degrees including the gorge.  Winds today
will be south 10-20 mph, gusty to 35 in elevation and easterly at times in the gorge to 20 mph. 
I expect rain to pick up in the north valley through mid-morning.  The main rain zone will life north 
to Longview early this afternoon, bringing a rain break with showers this afternoon to Portland and Salem.   
The rain break will help limit high water spots.  24-hour rainfall today near 1.00” in the flat
of the valley. Temps across the region will be near and above 60 degrees. 

TONIGHT:  Rain picks up with waves of steady rain overnight, with steady temps in the mid 50s to 60 degrees and south breezes. 

FRIDAY:  THE MAIN RAIN EVENT as a cold front drops southward into the valley and stalls with the upper
flow pattern overriding.  This will be the so called atmospheric river plume of moisture.  I expect steady rain, 
much of the day and into early evening.  24-hour rainfall amounts will likely exceed and inch and could be 
much higher if the front stalls for hours. Temps will hold 60-64 degrees across the region with southwest winds
10-20 mph. 

FRIDAY NIGHT:  Current timing as the rain dropping southeast of our region during the evening hours and the 
rain event coming to a close.  Low temps 46-53 degrees.  Total rainfall for the 60 hour event will exceed 2.00 inches in Portland. 

As of 10:00 a.m. Thursday morning, area rivers are projected to remain below flood stage through the event. 

Rod Hill