Today will be a transitional day with low clouds slowly burning off and few residual showers (see satellite pic at 10:15 AM). Want sunny skies for sure? Head just east of the Cascade crest and down into eastern Washington. The air is still cold aloft so we could get some instability and cumulus development, but that will be increasingly suppressed by high pressure building aloft.
Here is the 2 PM Satellite picture.... you see the mottled effect over land...but not clouds over water? A beautiful exam of surface heating causing lots of cumulus!
Here is the upper level (500 mb for tomorrow)--strong ridging over us and ridges are associated with sinking motion, which works against cloud formation.
With strong sun (the intensity today is like mid-August!) and warming temperatures aloft as the winds in the lower atmosphere turn southerly, temperatures will jump on Sunday into the 60s and even some lower 70s west of the Washington and Oregon Cascades. (see forecast for tomorrow afternoon from probcast). Summer will hit the Willamette Valley!
But another trough and an accompanying Pacific front will arrive on Monday...so this warmth won't last.
It is now certain that we will have the coldest April (maximum temperature) on record for Sea Tac (since 1948). And their are a whole collection of other regional cold records that will be broken as well. This month will be Portland's coldest April in 36 years as well as third wettest in history (1940-2011) at the Portland Airport. Astoria, Oregon has still not reached 60 degrees this calendar year, smashing the old record of April 19th 1945. I could go on and on, but I suspect you don't need much convincing.
Many of you have asked what this all portends for this summer's weather. To be honest, I can't tell you--there is simply no relationship that I know of that can provide a useful answer. One thing for sure...there will be plenty of water supply this summer for irrigation and power generation. And this says NOTHING about global warming.