Northwest Weather: Darkest Before the Dawn

Announcement

   I will be giving a talk on Northwest Weather and signing copies of my updated book (Weather of the Pacific Northwest) at the Northgate (Seattle) Barnes and Noble at 1 PM on Saturday, June 25th.  

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It is a well-known aphorism that it is always darkest before the dawn.   

And this wisdom may prove particularly applicable to the weather situation this week.  A major  improvement will soon occur

But first, let's talk about darkness.

330 PM Friday in Seattle.  It rarely gets worse than this in June.

On Friday, Seattle only received 4.64 MegaJoules per square meter of the surface (Joules are a unit of energy).    This is the darkest June day since June 2014.  June 9th was almost as dark.  And Saturday was only slightly brighter.  

Full sun this time of year should be around 900 watts per square meter.  

We have had several days with half that much

With cool, cloudy air over us, soil temperatures have stopped rising and started to decline, as shown by the soil temperatures at 8 inches in Seattle (below).   Your tomato plants are not happy.   No one is happy.

But I have good news.   Leading weather forecast models suggest we are going to break out of this infernal situation, at least for a while.

The Key Problem

The main reason we have been so cloudy, wet, and murky has been persistent low pressure or troughing along or just offshore of the West Coast.   Below is the upper level (about 18,000 ft) weather map for 11 AM Friday.   

Mama Mia!   A huge, high amplitude trough along the West Coast.  No wonder it was dark and abysmal around here.   

A persistent trough of one kind or another has been in place the last few months.  And this situation is about to change.

Examining the most potent, skillfull extended forecasting modeling system is the European Center's ensemble forecasting system.   Its latest forecast suggests that the upper-level trough will move inland a bit and weaken by Tuesday morning (pink indicates higher pressure--ridging, brown indicates lower pressure--troughing).  That will produce improving weather over the Northwest.

 On Thursday, a strong trough will pass to our north and a weak trough will remain over California. This will produce some decline in our weather.

But things look better on Saturday, as a deep trough develops well offshore and weak ridging extends along the coast.  A very different and MUCH more favorable pattern.

Sit down before I tell you the forecast for next weekend.    Saturday's temperatures, predicted by the National Weather Service Blend of Models (below), show the upper 70s in western WA and mid to upper 80s in the Columbia Basin.  Sunday will be nice as well.    It will seem like Paradise after what we went through the last few months.

And one more thing, based on the latest extended models, there is no hint of any possibility of getting a crazy heat wave like last June.   That was a black-swan event that will probably not happen again for many decades.