Sun and Warm Weather Is Here!

April 22, 2013

What a huge change in the past 24 hours!  We’ve from gloomy, cool, & damp to bright, sunny, & warm.  The long-awaited dry spell is here:

  • Dry weather is likely for at least 5 days, possibly through Saturday…possibly
  • Warmest weather should be Wednesday…somewhere in the mid 70s.
  • Onshore flow brings cooler temps and/or more cloud cover Thursday/Friday.

Hard to believe that 5 days ago models were showing an upper-level ridge building directly over us today through Wednesday.  Instead it has decided to park itself out around 140W, well offshore:

MarkSat_Sfc

That location is just about the “sweet spot” in winter that you want to get arctic air moving south into the Pacific Northwest on the back side of the upper level high.  In fact today’s dewpoints in the 20s with a NORTHERLY wind instead of more easterly is an obvious indication that a “cool” Canadian air mass has descended on the Pacific Northwest.  That’s similar to an October east wind period when we get frosty mornings and  cool afternoons in the 60s.  The huge difference is that we get as much energy from the sun in late April as we do in mid August!  Far different from October.  So our temps will jump the next two days by 7-10 degrees.

Nighttime temps will remain chilly; those areas that go calm will drop well down into the 30s.

I was tempted to make Thursday and Friday’s temps much cooler on our 7 Day forecast due to onshore flow developing ahead of an approaching upper-level trough.  But both our RPM and the WRF-GFS aren’t getting too crazy with the low-level moisture yet, so I left it alone.  Just be aware that Tuesday-Wednesday are the guaranteed nice days, Thursday-Friday are a bit up in the air.

Models are keying in on a cold trough swinging through the Pacific Northwest early next week (Sunday-Monday).  The ECMWF was very chilly and now the 18z GFS looks real cool as well.  So yes, another cool and possibly wet weekend is on the way.  Here are the two latest GFS/ECMWF ensemble charts:

tseries_850t_000-384_Portland_2

tseries_850t_000-360_Portland

 

That 18z GFS sure says SPRING with the up and down troughs and ridges doesn’t it?

Here are the 4 weekly maps from last night’s ECMWF monthly run:

500za_week1_bg_NA

500za_week2_bg_NA

500za_week3_bg_NA

500za_week4_bg_NA

Nothing that really sticks out beyond the 2nd week.

Enjoy the warm spring weather the next few days!

Chief Meteorologist Mark Nelsen