Weather Observations Near The Yarnell Hills Wildfire

Above is a regional radar chart from NCAR RAL for about 3 pm MST yesterday afternoon. The line of thunderstorms is more or less over the Bradshaw Mountains, north of where the wild fire would occur. Note that Wickenburg is just south of the bend in the western portion of the line between Maricopa County to the south and Yavapai County to the north. The dark blue echo, southwest of the arc of storms over Yavapai County, is near Yarnell. At 4 pm (below) the echoes in Yavapai County have weakened markedly, although a weak echo remains near Yarnell.

There is a BLM RAWS weather station (ID - Stanton Arziona) at 34.17N and 112.73W at an elevation of 3600 ft MSL. This RAWS site is approximately 3 miles south-southeast of Yarnell. At 4 pm yesterday the RAWS station reported a temperature of 103 F and RH of 14%. The wind was 216/22 mph, i.e. from the southwest at 22 mph. However at 5 pm the wind had shifted markedly to 020/41, i.e., from the north-northeast at 41 mph, apparently as a gust from the weakening convection passed the site. At 5 pm the direction remained nearly the same with speeds of 43 mph. Obviously, the rapidly changing winds and a downburst/outflow from thunderstorms played some role in the tragedy reported below. The map below shows the location of the BLM RAWS station relative to Yarnell.