Strong Winds Cause Major Expansion of Eastern Washington Wildfires

As feared, the great enhancement of cool, westerly winds caused a large increase in eastern Washington wildfires, with the Little Giant Fire expanding to Lake Chelan.

The change in visible satellite imagery yesterday shows the major changes

Early in the day Saturday, you can see the smoke from a few fires in eastern Washington, with the Little Giant Fire possessing only a modest amount of smoke.  Lots of low clouds in western Washington.

But later in the afternoon, as strong winds surged into eastern Washington, the fires exploded, with massive smoke plumes.

Here is a close-up at the same time.

The satellite image this morning shows a massive smoke cloud from the Little Giant fire extending into Montana and beyond.

Satellite sensors can pick up the emission from fires, and this morning's image of the Little Giant fire indicates a rapid spread of flames to the east, with some fire reaching Lake Chelan.

As noted earlier, this major fire blowup was associated with strong winds resulting from the movement of cooler, onshore flow into the region.  Cooler air associated with a Pacific weather system.

Below are the maximum winds over the region on Saturday.   At several locations,  wind reached 40-50 mph.

Zooming in to the area of the Little Giant fire, multiple locations surged to around 50 mph.

The strong winds were accompanied by profound cooling, something shown by the 24-hour temperature change (ending 6 AM this morning).  

Many locations were 20F cooler!  

The strong winds also resulted in some fire expansion near Spokane, which was picked up by weather radar yesterday:

The winds will calm down today, and the fire growth should greatly decline.   

In any case, this event illustrated the profound danger of lightning, dry fuels, and wind.  Often our big fires are associated with cooling weather, not heat waves.

But one thing has profoundly changed.   Our ability to PREDICT the winds is immensely better than 20 years ago, allowing far more effective preparation and protection for such events.

The question is whether society will properly take advantage of this forecasting prowess, including de-energizing powerlines.

Precipitation During the Driest Time of the Year: But a Threat Exists

Rain is coming to western Washington and the Cascades during the climatologically driest time of the year.

But there is an accompanying risk that needs to be mentioned.  

A severe enough risk that at least one local power company (Chelan PUD) may de-energize its lines:

A winter-looking system is off our coast, including an impressive cold front (indicated by a red arrow) and a low center at the center of swirling clouds.

This impressive summer system is associated with a relatively strong upper-level trough, as shown by the 500 hPa heights (think pressure at 18,000 ft) tomorrow at 11 AM.

Not your typical mid-summer pattern 😊

Precipitation will move in on Saturday morning.   The predicted totals through 5 PM Saturday (shown below) will be most substantial on the windward sides of regional terrain (up to about .5 inches).  

Accompanied by cool air, this event should greatly reduce the potential for wildfires west of the Cascade crests for a week or so.    

Some light showers will continue into Sunday, but the totals through Monday morning will be only a bit more:

So far, good news.  Reduce westside fire potential and lessen water needs for days.

However, there is a risk factor that needs to be mentioned: increased surface westerly winds east of the Cascade crests, which are driven by the accumulated cool air over western Washington, as well as increased winds at crest level.

Consider the forecast wind gusts on Saturday afternoon.  Strong westerly winds from Yakima to Omak, with substantial gusts extending into the Columbia Basin.  Maybe even some dust storms.

Winds that could damage powerlines and contribute to new wildfires.

Here are the forecast winds from the UW's highest resolution model.  The biggest threat east of Lake Chelan and Wenachee. 

Consider Camp 4 on Lake Chelan ( red dot below)

The predicted sustained winds by the UW modeling system at this location are substantial, with sustained winds reaching 20 kt or more.

The threat is that some of the fires in eastern WA could be enhanced and rapidly spread by these strong westerly winds on Saturday.  

 If you are located east of a current fire, great caution is advisable.