Back when we were in the thralls of a riveting snow event in late February, We trotted out these maps from the University of Washington forecast models that showed predicted snow totals for the lowlands. Sure, they didn't bat 1.000 but overall, these maps do OK.
With lowland snow but a distant memory and heavy rains now in the forecast, you might be interested to know the UW model also puts out similar charts for anticipated 24 hour rainfall.
And for this event, the models do a great job of highlighting an expected rain shadow that could form over the greater Seattle area.
This particular map shows expected 24 hour rain accumulation from 5 a.m. Wednesday through 5 a.m. Thursday.
The legend is on the right side and it's for hundredths of an inch of rain. So when it says "8" that's 0.08" of rain. "128" is 1.28".
Note for Seattle proper, it's only expecting anywhere from 0.04" to 0.16" as we're near the heart of the rain shadow. (Some spots on North Kitsap may not get any rain beyond some drizzle?) Meanwhile, just go a little bit outside the Seattle area go well over 1/2" and into several inches once you reach the mountains.
This is typically the dry benefit that Sequim receives with our predominant southwesterly flow during rainy events. But this time, the rain train is coming from the due west, meaning Seattle gets the benefit of the natural umbrella. (Ironically in my using the snow maps as a reference to these maps, it was a similar "snow shadow" that flunked the Seattle snow in late February.)
If you want to search these maps yourself, you can check out these links: