You are likely aware of the deadly Yarnell, Arizona fire that killed 19 firefighters, including young men from here in the Northwest. Below is a depiction of the seasonal weather pattern that produced the blaze.
The fire was sparked by lightning. Strong winds, dry air, record heat and severe drought conditions all led to the intensity of the blaze. Lightning storms are common in the Southwest during the summer months due to a seasonal or monsoon weather pattern. As the Arizona sun creates intense summer heat, the hot air rises. An area of low pressure develops and winds shift to fill in the vacuum. This seasonal weather pattern develops the low pressure center promoting rising air and thunderstorm development.
The monsoon pattern does bring much needed rainfall but also produces deadly lightning. In the Southwest, lightning has ignited more than 2,300 fires annually since the year 2001. These fires have burned some 277,000 acres per year.
During the Yarnell fire, Prescott, Arizona reported gusty winds to 28 mph. The Sunday afternoon in question reported thunderstorms that are thought to have switched the wind direction and produced strong wind gusts, helping the fire to grow rapidly. Thunderstorms in the area were mostly dry and temperatures in the area soared to 102 degrees, tying a record high in nearby Prescott. A large area of high pressure aloft continues to be anchored over the area, producing the heat. The high is seen above with the enclosed circle and orange color over the Southwest. Much of Arizona continues to experience severe to extreme drought conditions.
KGW Meteorologist Rod Hill, follow me @