The figure above indicates the forecasted high in orange (with error bar denoting the range of ensemble forecast members), average high for this time of year in orange (dashed line), forecasted low in blue (with error bar), average low this time of year in blue (dashed line), and forecasted wind speed in purple. Note that the wind speed forecast is sustained wind (not gusts), and it is based on only one model (not an ensemble).
A large, strong cyclone will circulate moist, unstable air northward across Arizona from the subtropics for the next couple of days and slowly move across the state on Friday. An unusually strong subtropical jet stream aloft (winds up to 110 mph or more) will create very strong vertical wind shear. This pattern is reminiscent of the storm pattern that produced a number of large hail and a tornado outbreak across central and northern Arizona almost exactly two years ago (October 5-6, 2010), except that this system is a little colder, and faster moving.
Expect scattered thunderstorms to begin developing in the mid to late afternoon on Thursday, and become more widespread Thursday evening through Friday morning. Thursday afternoon and evening, one could expect strong gusty wind, especially near thunderstorms, gusting to 60 mph or more in isolated areas. Otherwise, wind will be generally 20-30 mph from the south, gusting up to 40 mph. Winds will die down gradually overnight on Thursday, but scattered thunderstorms are likely Thursday night – Friday afternoon. Some thunderstorms may become severe, with large hail or isolated tornadoes possible. Thunderstorm motion will generally be toward the north or north or northeast between 20 and 40 mph.
Temperatures will be about 15 degrees cooler on Friday, then gradually warm up this weekend and early next week as high pressure rebuilds over the Southwest.
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Official National Weather Service forecast: