Thursday, August 27, 2015

Strong Cold Front on Saturday

You've probably already heard about the change in the weather for this weekend.  Yet another strong summer front will be moving through the Pacific NW.  And yes, it will bring the potential for rain to the area.  Unfortunately, it doesn't look like much for our side of the Cascades.  Let's take a look at 4 models forecast of 24 hour rainfall for Saturday and Saturday night.  First, here's the GFS

GFS forecast of 24 hour precipitation ending 5am Sunday 30 Aug

The GFS shows the majority of the rain falling over western WA and into BC.  This would bring rain to the Cascade fires, but not as much to the rest of the fires in the Inland Northwest.  Here's the NAM forecast:

NAM forecast of 24 hour precipitation ending 5am Sunday 30 Aug
The NAM paints a similar picture.  But you'll notice more rain that is forecast east of the Cascades near Omak.  This would obviously be great new for the Okanogan Complex and North Star fire.  It's also a bit wetter in the Idaho Panhandle, which would be equally good news.  Now let's look at the Canadian forecast:
GEM forecast of 24 hour precipitation ending 5am Sunday 30 Aug

The Canadian GEM model has been consistently the driest for the Inland NW. This would bring less than 0.10" of rain to the fires.  And one last model to look at:
Forecast of 24 hour precipitation ending 5am Sunday 30 Aug

Similar to the other models.  Heavy rain in western Washington and the Cascades, much less in eastern Washington.

But the bigger story will be the wind.  This storm will be similar to the system we had 2 weeks ago on August 14th.  Here's the current wind forecast:

These are sustained winds, and will be 30-40 mph in much of the Basin, Palouse, and Spokane area.  And here's the forecast wind gust:

Wind gusts of 45 to 55 mph.  This is a strong front.  The winds might actually subside a bit in the afternoon after the front moves through the area.

These kind of winds will cause more blowing dust, similar to August 14th.  Here's what the satellite looked like on that day:

MODIS satellite image showing wild fire smoke and blowing dust on 14 August
The blowing dust in the light brown streaks in the middle of the image.  This event closed down Interstate 90 and Highway 395.  Here's some images from the metroforensics blog:

The wind may also cause problems with the numerous wild fires in our area.  Here's a map showing the active fires that are currently burning.  

Wildfires in the Inland NW 27 August

The cold front will move through the region in the morning with very strong winds.  These winds could cause wild fires to spread quickly.  Eventually the atmosphere will become moister as the temperature falls and moisture arrives.  This could help the fire situation.  The window between the frontal passage and the moisture arrival will hopefully be short, keeping fire danger to a minimum.  But if there are several hours in that window, some of the fires could make significant runs to the north and east.

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