Labor Day Weekend - Heat, wind, elevated fire concerns, and potential dust

Have plans for the Labor Day Weekend?  We have heat, potentially critical fire weather concerns as well as blowing dust to discuss.

First let's talk about the dry conditions.  The Inland NW has been very dry since July 1st as noted by this graphic.

% of normal precipitation July-August 2020

Central Washington has been bone dry.  The NE Washington Mountains and the Idaho Panhandle has received only about half of normal precipitation.  That said, the fire danger class rating from Sept 2nd indicated high to very high very danger across much of the western US including Central and Eastern Washington and north Idaho.

Thankfully, despite the high fire danger, most of the current large fires are south of our region with air quality not looking too bad.   The exception is the Evans Canyon Fire near Naches, WA which has been producing a continuous feed of smoke the past few days and occasionally impacting air quality in some areas.  Part of the reason for the lack of fires in Washington so far is below normal lightning where NWCC (Northwest Interagency Coordination Center) has reported only 30% of normal lightning strikes for Washington and Oregon combined from June through August. 

Air Quality readings at 12 PM PDT Sept 3rd, 2020

For the current version of this map, click here

So what about the Labor Day Weekend?  Strong high pressure over the western US (as shown below) will deliver temperatures well above normal, with Friday likely one of the hottest days.

GEFS 500mb heights and anomlies valid 11 AM PDT Friday, Sept 4th, 2020

In fact, records may be in jeopardy at some locations.  Here is a look at our forecast for Friday compared to records for the day.

Now, look at the change by the end of the Labor Day Weekend.  Dust and fire concerns will increase significantly.  Saturday and Sunday locally breezy winds will occur near the Cascades.  On Monday strong high pressure shifts west off the coast, allowing a cold front to drop in from the north.

GEFS 500mb heights and anomlies valid 11 AM PDT Monday, Sept 7th, 2020

The combination of increased winds and dry conditions will further increase fire danger.  A summary of fire concerns is listed below along with burn ban information

Here is a clickable version of the burn restriction links from above graphic

WA DNR

Idaho DEQ

Here is one model depiction for Monday showing windy conditions over much of the region out of the north to northeast.  The numbers depict free air wind speeds near 5000 feet MSL and a general representation of wind gust potential.  This pattern typical favors the Okanogan Valley, Columbia Basin, and the North Idaho Panhandle from Sandpoint down to Coeur d'Alene with the windiest conditions.

GFS 850mb winds and heights valid 11 AM PDT Monday, Sept 7th, 2020

These winds combined with low relative humidity will elevate concerns for rapid fire spread with any new fire starts.  The winds may also bring choppy water on area lakes.

Blowing dust is also a concern due to several freshly plowed fields across the Columbia Basin and Waterville Plateau.  Soil moisture is very dry over the region especially Central WA and across the Columbia Basin with little to rain over the past 60 days

Total precipitation July 5th-Sept 2nd, 2020.  Blue numbers on map are observed values from area weather stations.

To summarize, heat will initially be the main concern with record highs possible Friday in some areas.  Focus then shifts towards blowing dust, increased fire danger, and rough lakes by Labor Day.  

Have a fun and safe Labor Day weekend!