The Fall Transition Has Begun

 One of the most remarkable aspects of Northwest climate is the rapid fall transition from summerlike conditions to cold and wet between September 1 and November 1.

This is illustrated by the average temperatures at Seattle (below).  

The current temperature forecasts are close to climatology, with no more 90s or 80s.

Climatological precipitation is on a very steep incline up (probability of measurable precipitation is shown below).  By November 1, we are about as wet as we get.

A wet weather system is now right off our coast and will move in tonight and tomorrow (see infrared satellite image for this evening).  Does not look like a summer pattern!

Rain totals through Thursday morning (shown below) will be significant.  Importantly,  precipitation will extend over eastern Washington, where some fires are still smoldering.

The official NOAA 6-10 day forecasts are for cooler-than-normal and wetter-than-normal conditions over the West Coast:

The timing of this cool/wet weather is perfect to facilitate an early end to the serious wildfire season.

With Cool/Wet Weather Ahead, The Wildfire Threat Will Rapidly Decline over the Pacific Northwest

For those concerned about the wildfire threat over the Pacific Northwest, there is good news. 

With the turn to cooler/wetter weather and a forecast for much more, the wildfire threat should rapidly decline over the Pacific Northwest.

Below is the latest wildfire satellite image, with active fires shown by red dots.  Only two fire areas are evident.  Currently, there is not much active fire activity over the entire West Coast.  California is having a very benign fire year, with roughly half the acreage of the five-year average.

Recent rainfall has greatly damped down the fires over the Pacific Northwest, and the US Forest Service is predicting that fuel moistures will decline to near climatological levels this week (see below).

Looking to the future, let's check out the latest forecasts (below).   For the next five days, the region is predicted to be substantially cooler than normal, indicated by green and blue colors.

The next five days?  Even cooler than normal  (below).  Eastern WA and Oregon, where most of the fire activity has occurred, will be particularly cold.

And there will be plenty of precipitation during that period as well.  Here is the European Center AI forecast for total precipitation through September 9.  Lots of precipitation.

The UW WRF model forecast, run by my group, is more detailed but similar (below).  Lots of rain will be falling.  Some higher elevations will get snow.

Furthermore, there are no forecasts for a major wind event on either side of the Cascades.

There are some folks claiming that we are now at the "peak"  of the wildfire season, but that is not correct.   

This is the endgame for the wildfire season for our region.    Yes, there will will be some smoldering for a few of the fires, but the big action will be over.