Hurricane Jimena (IR image at 14Z above) will move north of 20N tonight and low-level moisture will push strongly into the lower Colorado River Basin. Note that Jimena has a very large cloud shield associated with it. Moisture continues a slow increase over southern AZ with quite a bit of cloud cover and a few showers over the southwest part of the state and drier conditions to the southeast. Impacts from Hurricanes moving along Jimena's predicted path usually occur sooner than expected here. Later, when the decaying storm moves north, the details are determined by the final path of the disturbance.
There was a slight uptick in storms yesterday - thunder and outflows around town with some rain on the Catalinas. Five of 93 ALERT stations had measurable rain but amounts were light. The really strong push of GoC moisture has yet to materialize, but the morning soundings at Tucson and Phoenix have very steep lapse rates and with the current amount of moisture present it appears that there will be CAPE in the lower elevations this afternoon. The NAM forecasts increasing easterly steering winds during the evening as the first disturbance over the GoC squeezes north - thus, there will be a good chance for storms with downbursts during the late afternoon and evening, and some of these may produce severe winds and dust.
Tomorrow, and beyond, depends upon a myriad of complex mesoscale details that will be determined by storms today, cloud cover, strength of easterly winds, exact track of Jimena, and etc. Hurricanes Nora in September 1997 and Javier in September 2004 provide nice examples of how the final impact of tropical storms can differ widely here in southeast Arizona.
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