Extremely Dry; Any Hope For A Soaking?

August 6, 2015

9pm Thursday…

You are living through the driest late spring and early summer we’ve seen in many years.  In fact it’s the driest in 23 years!  Do you realize here in Portland we’ve seen less than 2″ of rain in 3 months?

MarkRain_DrySpellFacts

There have been 5 years (including this year) in which we’ve seen less than 2″ of rain during that May-July period.  That includes 1938, 1944, 1992, 2003, & 2015.  So if you depend on a well for water like I am, you might be wondering if there is any sort of significant rain in sight.  I’m getting a bit nervous; worried about what happens if we go 5-6 months without significant rain (April-September).  Good question.

It’s as if we’ve been transported to the Hood River or Rogue Valley.  Of course vegetation (trees and bushes) are adapted to those drier climates, but it’s quite a shock to our native vegetation.  So you should probably be watering trees/bushes that you don’t normally water

History tells us that extremely dry years often continue dry right on through August and often in September too.  In every year mentioned above, plus a few others with just over 2″, the dry conditions continued into early fall!  That’s not good news.  That said, there’s no reason the pattern can’t change and we get a week or two of cool and wet weather within the next month.

So will the pattern change?  Short term we have a cooler and wetter pattern Sunday through Tuesday (and maybe Wednesday) of next week.

MarkJetStream

Take a look at the pattern; a cool upper-level trough moves to just offshore, sending surges of showers up over the Pacific Northwest.  This would be the June weather that we missed this year…in August.  After Tuesday models are in total disagreement; the ECMWF gets the trough out of there, the GFS keeps it around through late week.  Note the much higher rain totals on the GFS, especially in the southern half of Oregon:

gfs_00z_pcp

vs. the ECMWF which just gives the valleys of western Oregon light showers here and there:

ecmwf_12z_pcp

How about further into the future?  The monthly run from the ECMWF is very dry, showing 1″ or less in the next month over most of the western lowlands in Oregon.  That takes us into the first week of September.  The CFS model latest run shows less than 1″ through the end of August:

cfs_aug

So, most likely we don’t have a week or two of rain ahead, at least rain that would make a meaningful contribution to our yards and veggies.

The good news is that the cool and moist/wet weather for next week is EXCELLENT news for the fires burning around the region.  I have a feeling that one week from now there might not be any big blazes “out of control” in Oregon.  In fact the NW Interagency Fire Center forecast shows lots of green and yellow (low fire danger) as we go into next week.  Eastside that forecast is a bit tougher because of lightning with the showers.  In general though the next 7 days should put quite a damper on fire action at just the right time.

Chief Meteorologist Mark Nelsen