Originally Published: October 11, 2012 4:01 p.m.
Prescott is likely to get its first rain today since monsoon season ended exactly one month ago, and it could be accompanied by severe weather.
A strong fall storm system has moved off the Pacific Ocean and is headed through Arizona today and Friday.
It could bring three-quarters of an inch of rain to northern Arizona, strong gusty winds, a 15-20 degree drop in temperatures by Friday, and even the possibility of a tornado.
The storm system is similar to one that struck northern Arizona on Oct. 5-6, 2010. It produced hail and numerous tornadoes in the Flagstaff area, as well as a few smaller tornadoes in eastern Yavapai County.
"Our severe weather expert Dave Blanchard thinks there may actually be a tornado somewhere in northern Arizona" with this storm as well, said Dave Vonderheide at the National Weather Service office in Flagstaff.
The Weather Service expects a 50 percent chance of scattered thunderstorms by this afternoon in Prescott, followed by a 90 percent chance of rain tonight.
Gusty winds of 30 mph today could tear fall leaves prematurely from trees and ruin Halloween décor.
Friday's forecast calls for a 60 percent chance of rain in Prescott and high temperature of only 60 degrees. The low could drop to 40 degrees. The storm should move out by early afternoon.
Areas above 7,500 feet could get snow Friday.
This is the first time the Prescott area has seen any precipitation since the monsoon weather pattern brought its final rains on Sept. 11.
The monsoon produced a total of 5.84 inches of rain at Prescott's Sundog measuring site in July through September. That's only 76 percent of the 104-year average of 7.76 inches.
July saw 3.19 inches of rain or 111 percent of the average, followed by 1.8 inches in August (56 percent of average) and 0.85 inches in September (50 percent of average).
Monsoon rainfall totals were highly variable across northern Arizona, with 18 of 31 sites on a National Weather Service list getting above-average rains.
Monsoon rainfall totals in Yavapai County included 10 inches in Bagdad (187 percent of 30-year average), 5.05 inches in Castle Hot Springs (102 percent), 5.99 inches in Cottonwood (112 percent), 11.51 inches in Jerome (157 percent), 4.51 inches at Montezuma Castle National Monument near Camp Verde (76 percent), 6.53 inches at the Prescott airport (100 percent) and 8.6 inches at Seligman (154 percent).
Bagdad recorded the most rain over its 30-year average of any of the 31 sites.