After a very wet winter and early spring, I can't believe that I am looking forward to some rain....but it is true. Digging in my garden, the soil is dry to some depth and many folks are already starting to water. And the recent warm temperatures have greatly increased evaporation from the surface.
The precipitation for the past 4 weeks at Sea Tac (see below, red line is observed precipitation, blue line is normal), tells the story. After a relatively wet period during mid-May, the rain gauge nearly flatlined during the last two weeks.
Today's temps were well above normal, with a number of sites getting into the mid-80s around Puget Sound and SW Washington. You don't want to know about Portland and the Willamette Valley.
However, the latest infrared satellite image (see below) suggests major change, as an impressive area of clouds approaches the West Coast. Rain will arrive late Wednesday night.
The clouds are associated with a huge upper trough of low pressure that will amplify over the eastern Pacific. Here is the impressive upper level height forecast for 8 AM Friday---pretty amazing for this time of year. A strong jet stream (where the lines are close together) pushes far south into northern CA.
The forecast 24h precipitation totals ending 5 AM Thursday show the initial pulse of overnight precipitation.
You won't need an air conditioner or a fan after tomorrow for quite a while.
Wednesday will get near 80F for some, but after that we will fall into the 60s for a least a week.