Average Spring So Far Plus May Starts Warm

May 1, 2018

7pm Tuesday

Ahhh, I see we’ve entered the warm season now with a typical “clouds lasted all day” forecast bust.  Seems appropriate for the first day of May.  There was enough onshore flow to keep the clouds locked in most areas west of the Cascades today; I had expected widespread clearing this afternoon.  You can find plenty of clearing on the satellite image…but it’s east of the Cascades and in the eastern Gorge.

vis

That led to a cool day of course

Todays Observed Highs OrWa 2017

 

Tonight the clouds will linger some areas and partially break up in others.

Weak offshore flow tomorrow should clear us out.  That plus a warming atmosphere overhead means a MUCH warmer day.  We’ll go from around 60 today to mid 70s tomorrow!

Tomorrow marks the beginning of another prolonged stretch of warm & dry weather. Most likely we’ll see mainly above average temperatures through the 10th of the month.  That’s because upper-level ridging develops the 2nd half of the week; note the 500 millibar height anomaly from the ECMWF ensembles (EPS).  This is Friday:

Friday_500

Then next Monday afternoon, the 7th:

Monday_500

Notice the ridging is a little farther east.  Then next Thursday, the 10th:

Thursday_500

By later next week the ridging is centered over the Rockies but this is still a very warm pattern for us anytime during the warm season.

Take a look at ensemble rain forecasts. Each of the horizontal lines on the top half of the chart below is just ONE of the ensemble’s 51 members.  Time goes from now through the 15th of May.  The blue on the bottom is the average of all the members.  Note that we’re just about guaranteed dry through Friday now.  A few ensemble members are still trying to develop (light) showers over us Saturday & Sunday.  But in general things are looking dry through about next Tuesday.  The chance for showers/rain goes up the 2nd half of next week as that ridge pushes farther east.  Looks like more than half the members produce rain at some point late next week.

KPDX_2018050112_eps24_precip_360

So enjoy another taste of June over the next week.  It could be a lot wetter/cooler this time of year!

By the way, check out spring so far…as normal as it gets!

TEMPERATURE: A cool March but warm April (2nd warmest April of the past 10 years)

Mark Spring So Far 1

RAIN:  After all that complaining early in April???  We’re back to normal or slightly DRY for the season.  Hard to believe isn’t it?  Drier than normal in March and then just a little above average in April.

Mark Spring So Far 2

Chief Meteorologist Mark Nelsen