The Northwest's Summer Drought Will End on Sunday

It has been an amazingly dry late summer, with very little rain during a period when showers typically return.

If you want to be impressed, here is the cumulative precipitation at Sea-Tac Airport for the last 6 months that actually occurred (purple) and which is normal (blue).   You might be startled to note that the precipitation for the past 6 months has actually been ABOVE normal, but that was due to an unusually wet spring.  For most of the warm season (since approximately 15 June), Seattle's precipitation has been essentially flatlined.  Earlier in the summer (before late August) this is not that unusual, but having nothing for the first half of Sept. is not a common occurrence.

Dry conditions will continue through Saturday, so enjoy the nice weather while you can.  Here is the cumulative precipitation for the entire country from the NWS GFS model through 11 AM Sunday.  Washington is pretty much dry.

But later on the day on Sunday, the first substantial frontal system will come through...one that will provide a real wetting-down of the region.  The 24-h precipitation ending 5 AM Monday provides the story, with 1-2 inches in the mountains and light rain east of the Cascade crest.  This event will provide substantial aid for reducing the wildfires that are still burning in our region.

The cooler weather of late has restrained the regional fires-- as shown by the MODIS satellite imagery yesterday, many of the fires are still burning, with local smoke.  But the huge plumes of the past few weeks are not apparent.

 The excellent weather.com forecasts for Seattle (partially based on National Weather Service models),  show that the really warm temperatures  (85F and more) are history for us, with 70s and then 60sF in our future.  The sun's radiation is rapidly weakening now as the day's shorten---and the atmosphere is finally responding.

from Cliff Mass Weather and Climate Blog http://ift.tt/2ff4DVp