Warm Weekend Is Here!

April 20, 2012

What a beautiful weekend on the way with abundant sunshine and temperatures topping out between 72 and 82 Saturday, Sunday, and Monday too!  The next chance for any rain would be Monday evening, just a slight chance of a thunderstorm or shower at that time.

The last two years we’ve had to wait until June to see 80 degree temperatures.  This year should be different; I think it’s very likely we hit 80 in most spots west of the Cascades either Saturday and/or Sunday.

Everything is working out as models anticipated this evening.  The baroclinic band of clouds and rain is lifting north, a warm atmosphere is poised to move in overhead tomorrow, and skies are starting to clear.  Due to models continuing to show 850mb temps around +12 to +14 Sunday and Monday afternoons, I figured it was time to push high temps to 80 on the 7 Day forecast.  I could see as high as 83 in the metro area Sunday too since there appears to be very light offshore flow in the lower levels of the atmosphere; you can see it nicely (wind barbs from the east) on the WRF-GFS cross-section from 00z this evening from tomorrow evening through Monday morning:

You can see a total lack of low-level moisture from late morning tomorrow through Monday night…lots of sun and bright skies.  Enjoy the best weekend of 2012!

Both our RPM and the WRF-GFS definitely imply some afternoon convection at least over the Cascades Monday afternoon/evening, possibly spreading north Monday night.  With such a warm atmosphere and moist southerly flow, it sure seems possible.  Something to keep an eye on…

There are hints that we get a marine push for Tuesday west of the Cascades (it shows up on that cross-section above too).  If so, temps will be MUCH cooler, but forecasting a big push 4 days ahead of time is tough.

A cold upper-level trough is still forecast to approach the Pacific Northwest the 2nd half of next week, bringing back the normal weather, that would be much cooler with showers.

Here’s the latest 12z ECMWF ensemble chart:

It shows cooler than average weather continuing beyond late next week.  The GFS keeps trying to bring back at least weak ridging for the last weekend of April…here’s the 18z version:

Chief Meteorologist Mark Nelsen