Atmospheric River Update: Heavy Rain & Breezy on Thursday

 FastCast—Thursday, Oct. 28 to Friday, Oct. 29:

Steady light rain has been falling since late Wednesday afternoon from Seattle southward. Expect a break in the rain on Thursday morning & into the early afternoon. The atmospheric river will impact areas north of Seattle earlier in the day, and will shift south by Thursday evening, bringing steady rain, heavy at times, from Everett southward. Rain may linger into Friday, but will likely end by Friday afternoon. Rain totals will be in the 1 to 2.5 inch range for much of the interior lowlands, with some isolated higher totals. River flooding is possible due to high mountain rain totals and very high snow levels. Winds gusting up to 30-40 mph are possible on Thursday as well, strongest near water. Expect highs in the low 60s on Thursday and only around 50 on Friday. Thursday will also feel muggy, as dewpoints will rise into the upper 50s. Lows by Saturday morning will be in the upper 30s to low 40s as clouds clear out. For more information about rain totals, continue reading below.

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Continue reading the full blog below!

An atmospheric river is beginning to impact Western Washington. Steady light rain has been falling since Wednesday evening, mainly south of Everett. Rain will continue through early Thursday morning. 

From Seattle southward, a break in the rain is likely from early Thursday morning through early afternoon. The atmospheric river will bring heavy rain to the Northwest Interior before shifting south. From Everett southward, the heaviest rain will fall from around 1 PM Thursday to around 5 AM Friday.

Below is the UW forecast for rain totals by Friday evening.

Rain totals will be substantial to say the least. Expect 1-2.5 inches in the interior lowlands, with isolated higher amounts possible. On the coast, 2-3 inches are likely north of Aberdeen, and in the mountains, 3-10 inches are expected, most in the Olympics and Cascades north of Snoqualmie Pass. 

High mountain rain totals and snow levels around 9,000 feet will contribute to potential river flooding. See river observations here: 

https://water.weather.gov/ahps2/index.php?wfo=sew

In addition to river flooding, urban flooding is possible due to all the leaves in and around storm drains. Be aware of standing water and ponding, especially from Thursday evening to Friday morning.

A weak low center will move past Western Washington on Thursday as well, with gusty winds possible. See the Windy app forecast for Federal Way below.

(How to read: big numbers are sustained winds, small numbers are gusts, arrows are wind direction.)

Expect winds gusting up to 30-40 mph from Thursday morning to evening, strongest near the water. As always, there’s a chance of tree damage and isolated power outages…so be prepared!

A break in the rain & clouds is coming soon. Sunny weather is expected for the weekend!