10 October 2017

California Burning on Such A Snowy Day

Posted by Dan Satterfield

This the 3km WRF model at Midnight California time showing winds at 900 millibars (around 1 km above sea level). Winds over 50 knots are blowing from the East toward the coast, and warming as the air compresses.

Snow in Boulder today. Pic from NWS Denver.

The snow in Denver and the firestorm in California today are intimately connected. When a strong high-pressure system moves into Utah and Colorado, the winds blow from the northeast over the Sierra’s and the Coast Range in California. Air has weight and it accelerates as it rolls downhill and it also accelerates as it is funnelled into the canyons. The result is an air mass that was already dry, being warmed by compression as it falls, and this drops the relative humidity to even lower levels.

After that, all you need is dry fuel and a spark. Both were present early this morning near Santa Rosa California. The result: A deadly firestorm. This all happened Monday as cold air moved into the Rockies, giving Denver its first snowfall of the season and pushing strong winds over the mountains and through the canyons near Santa Rosa, Ca. In southern California, these winds are called Santa Ana’s, but they call them El Diablo (the Devil) in Northern California. (A fact I did not know and learned here.)

The image below is from the NASA Aqua satellite in true color. Click the image for 500-meter resolution.

It looks more and more likely that this will be the future of California (as the climate continues to warm) because research shows that the increasing number of warm years make it more likely that they will coincide with drought years. The paper to read is here. An exc. commentary on this paper was published with it by Dr’s Peter Gleick and Michael Mann.

After you read these papers, congratulate yourself. You now understand more science than the head of the Environmental Protection Agency.