8 AM update
Lots of heavy showers and thunderstorms moving through here is the latest radar. Yellow are heavy showers....and there are even some reds (downpours or hail) in a few cells.
and the lightning during the half-hour ending 7 AM in shown below. Not much lighting in easternWA yet. Lots on the eastern side of Puget Sound.
*We are now entering the climatologically driest period of the year, with the last week of July/first week of August being the most arid of the year. July is usually our driest month, and this year has been drier than most (only a trace of rain so far at Sea-Tac airport).
But everything changes tomorrow, when a July deluge is forecast by our weather forecasting models.
Just to impress you. Here is the 48h total precipitation predictions to occur starting 5 PM Tuesday and ending 5 PM Thursday. Wow. The western slopes and crest of the Cascades get hammered, with totals of 1-3 inches. Even the western lowlands get quite wet, with modest amounts extending into eastern Washington. Not a good time for hiking or camping in the Cascades.
This heavy rain is associated with the approach of a sharp upper-level trough/low (see upper-level map for 5 PM on Wednesday.) Pretty impressive this time of the year.
This air is potentially unstable and there could well be some embedded thunderstorms.
The rain should start moving in around 8 AM
Strengthen and move northward during the day
And then we get more rain on the backside of the low on Thursday AM
I expect several local stations to exceed their daily records if the models are right.