August 05, 2025

A Summertime Atmospheric River Will Reach the Northwest Tomorrow

 The coastal radar is already picking up the incoming rain offshore (see below).


Impressively, the UW modeling system shows a moderate atmospheric river heading for our coast at 5 PM today.

And the San Diego Atmospheric River (AR) center at Scripps is forecasting AR-1 conditions on our coast!


Note scared yet? 

You will be.

Below is the predicted total rainfall through 5 AM Thursday.  Wow.

All of western Washington is soaked and large portions of northeastern WA gets thoroughly wetted down.   

Some locations on the western side of the Cascades will receive 1.5- 2 inches.  That is a LOT for this time of the year.    Importantly, the Olympics will get enough to slow the Bear Gulch fire.



What about time and uncertainty?   The best tool for this is to look at the UW ensemble forecasts from many model runs (below) for Seattle.

All the forecasts are going for rain, with the wet fun starting around 3 AM and continuing into early or mid-afternoon tomorrow (Wednesday).


The mean total for the entire event in Seattle is about 0.4 inches.

Folks...this is unusual.  

Below are the record precipitation totals for August 6 at Seattle.   It is quite possible that tomorrow could be the third wettest August 6th on record at that location.


You will tell your grandchildren about it someday. 😀  And yes, you better find that umbrella.




8 comments:

  1. Sounds great. Should refill my water barrel!

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  2. This is early enough it should avoid splitting our tomatoes, and will be very welcomed by the rest of our garden and yard.

    There's even a little bit of snow showing in the UW GFS maps for the top of Rainier.

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  3. Were the models for this event a little too optimistic? I understand that showers are still going on in a few places, but it seems that we received far less than forecasted in North Seattle. Pretty disappointing that we didn't get a better soaking.

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  4. well that was a bust, barely showed on my rsin gauge

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  5. hardly any rain, barely showed on my rain gauge

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  6. First “Autumn” storm, judging the rain, wind, humidity and temperature. This may be August, and over a month from the Equinox, but as this system passes it has the character of Fall.

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    Replies
    1. By the way, Prof, at least here in NE Seattle, we are well over 0.6 inches, but in a gauge right now unsuitable and, due to construction, in a second choice location. I’d say the forecast was accurate for our location. This storm makes this August already unusual and August is just getting started. What are long range models looking for the rest of this month as solar energy declines as we head toward the equinox?

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  7. Ahh, most excellent. Got half an inch so far n the foothills which we badly needed. Does the unusually warm Pacific have anything to do with this weather?

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Please make sure your comments are civil. Name calling and personal attacks are not appropriate.

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