Drier With Gap Winds, Then A Return To Rain

After 2-5 inches of rain to start January, we have come to a small break in the rain.

Thursday will be a dry day, with patchy fog around the area in the morning.

Starting Thursday afternoon, a cross-Cascade pressure gradient will build, due to a low pressure system offshore and a high pressure ridge inland. 

Winds will accelerate through the gaps in the Cascades Thursday afternoon through early Friday morning. In favored locations, these easterly winds will gust 30-50 mph, strongest closer to the foothills.

These winds are very localized, with current guidance showing the strongest winds to be around North Bend. Expect a possibility of gusty east winds in the outlined area.

Following the gusty winds, the next round of rain will move in to the area late Thursday night into Friday. The UW model for precipitation shows light rain, totaling 0.05-0.2 inches through Friday afternoon.

A chance of rain remains through the weekend, with rain likely again to begin next week.

Additionally, there is an elevated threat of landslides in Western Washington due to recent heavy rain. Soils are saturated and any winds (possibly the upcoming gap winds) could result in some tree damage.

More Rain, Winds, and Mountain Snow

After a very wet day on Saturday, the weather has calmed a bit across Western Washington. 

Most locations in the South Sound recorded 0.1-0.5 inches of rain Sunday morning. After a short break, more rain is coming from Sunday night to Wednesday night. 

Below is the UW forecast model showing rain through 4 AM Wednesday.

Expect 0.5-2.5 inches of rain in the lowlands, with more on the coast & in the mountains.

Most rain will fall between Sunday night and Monday night, with rain much lighter than Saturday. Then, expect another wave of rain from Tuesday morning through Wednesday afternoon. 

In addition, the mountains will get another walloping of snow. The UW forecast through 4 AM Wednesday is below.

Wow. Expect snowfall of 8-18 inches over the mountain passes and 2-4 FEET in the higher elevations.

It looks like another couple days of difficult mountain pass travel. Be prepared for winter storm conditions if you’re traveling over the passes.

One more component of the weather systems on Monday and Tuesday will be wind.

The wind forecast (above) for Puyallup shows a chance of winds gusting 20-40 mph on Monday. Similar winds are possible on Tuesday as well. 

Due to the very saturated ground, some localized tree damage is possible.

Large amounts of rain have fallen across Western Washington, which is leading to high soil moisture/instability and an increased threat of landslides. (Graphic from NWS Seattle)

The rain has also led to rises on rivers flowing off the Cascades. 

A break from the rain is likely by Thursday, when some partly sunny weather (yes, you did read that right) is possible!

Heavy Rain, Mountain Snow Impacting Western Washington

Heavy rain, totaling 0.75-2 inches, has fallen across Western Washington on Saturday. 

This rain has prompted an Urban & Small Stream Flood Advisory until 11:45 PM Saturday. The alert is below.

Flooding is possible on streets, in streams, in low-lying areas, and in areas with poor drainage. Additionally, rises are occurring on area rivers.

How much rain has fallen?

In the 6-hour period of 4:30-10:30 PM Saturday, over a half inch fell across most of the South Sound!

The 24 hour totals (10:30 PM Friday-10:30 PM Saturday) are below. (Rain is still falling as I write this Saturday night).

Wow! Widespread amounts of 0.5-2 inches!

But wait, there’s more...

Heavy snow and downright messy travel conditions prompted the closure of I-90 over Snoqualmie Pass. Conditions had been bad all day, with gridlock in this 5:30 PM snapshot from a WSDOT camera.

About 2 hours later, the pass was closed both directions. As of 10:35 PM, I-90 is closed from North Bend to Ellensburg, nearly 75 miles, with no estimated reopening.

Mountain snow and lowland rain will continue through early Sunday morning, with 0.1-0.5 inches of lowland rain and 5-10 inches of mountain snow.

More weather systems will impact the area through the middle of the week, with another 0.5-2 inches of rain likely through Wednesday night.

This large amount of rain will bring an increased threat of landslides to Western Washington, outlined by this graphic from NWS Seattle.

Be safe, stay dry, and stay tuned!