Winds Drive the Explosive Substation Fire Near the Dalles

One of the most explosively growing fires in the nation occurred during the past two days near the Dalles, Oregon, just south of the Columbia River...and winds have been a big factor.  It appears to have begun about 5 miles SE of the Dalles around 3:30 PM Tuesday and has grown to over 50,000 acres (see map)

To get a feeling for the growth, let me show you a series of MODIS satellite images.  Below is a series of satellite images using wavelengths the show burned areas.  The Columbia River is evident, as is Mt. Hood.

 On Tuesday...nothing...but you can see some indication of the Columbia Gorge fire of last year.

 Wednesday.... a big area is evident, with a run of roughly 18 miles

Today around noon--extensive growth of the fire.

The fire is growing in grass, sage, and in some of the extensive wheat fields of the region.   Such fuels burn explosively and are known as "flashy".

The first was apparently human caused, with the media suggesting some kind of  criminal investigation.   Eastside grasses are typically dry this time of the year, so that is particularly unusual.    But looking at the temperature and humidity at the Dalles, temperatures were quite warm (around 100F) for the daya leading to the incident.

With warm, dry conditions over northeastern Oregon for the past month, the crop moisture index showed very dry conditions in the area of the fire.

But what about the winds, which can stoke a fire and cause it to run rapidly in space.  Winds really surged later on Tuesday, and have been blowing since then--sustained winds around 20-25 mph with gusts above 30 mph.  Highly predictable.

Ironically, the wind acceleration was associated with cool air moving into western Oregon and Washington, enhancing the pressure difference across the Columbia Gorge.  The winds should weaken tomorrow, as the west side of the region begins to warm.   Thus, there is a substantial hope that the fire will slow and hopefully brought under control.




from Cliff Mass Weather and Climate Blog https://ift.tt/2uRawz1