Improving Weekend Forecast

April 6, 2012

Here’s the latest forecast for the weekend, it looks like a pretty decent Easter Weekend on the way:

We’ve been waffling around a bit on the weekend forecast, generally going for a dry Saturday and a few showers Sunday.  4 days ago we had a nice Sunday as well.  That original forecast might turn out okay.

So why the changing forecasts?  The general weather pattern has been well agreed on by models; a cold upper-level trough lingering in the eastern Pacific this weekend and early next week, with a warm and building upper-level ridge just to our east.  We are inbetween the two, meaning that slight changes in the models east or westward with clouds and/or bands of rain makes a huge difference in the forecast.

The 00z models seem to be holding the clouds and rain slightly farther to the west (offshore) as the trough’s main energy remains offshore, it can be seen the in the 500mb forecast heights over us; thus the improving forecast.  We will be in upper level southerly flow for about 3 days from tomorrow afternoon through Tuesday afternoon.  In the spring, that’s a very mild pattern and you’ll notice our 7 day forecast is quite a bit warmer than what we’ve been seeing lately.  Instead of high temps around 50, we’ll be 60 or so.  And after tonight, low temps jump a good 10-15 degrees too.

One “fly in the ointment” is an east wind developing through the Gorge tonight through Easter Sunday due to high pressure over SW Canada and deep low pressure offshore seen here on the image to the left.    Those of you out in Corbett, Camas, Troutdale, Washougal; sorry, but it won’t feel too much warmer due to the gusty wind.  Of course that’s offshore flow which helps to warm up the rest of us.

Big Picture:  It’s finally going to feel like April!

Weekend high temperatures are totally dependent on cloud cover.  With that offshore flow and 850mb temps around +5 on Sunday, we could be well into the mid 60s or even higher if skies are mostly sunny.  I’m assuming there will be plenty of cloud cover and temps in the lower 60s.  Our 00z RPM came in significantly warmer with a high somewhere in the upper 60s Sunday.   It also shows very little rainfall through Monday afternoon, once again due to slightly higher upper level heights over us keeping most action offshore.  The 00z WRF-GFS keeps all rainfall to our southwest through at least Sunday morning too: 

Here is the latest ensemble chart from the GFS, normal or above normal (average) for 7-10 days, that would be nice:

And the ECMWF, seems to be a little cooler in general:

10:20pm Late Breaking Weather Picture:  Wow, Don Best did it again…sunset tonight at Rockaway Beach.  That INCLUDES, a couple holding hands, sun between the rocks, vivid color, and a happy dog nearby.


Chief Meteorologist Mark Nelsen