Thursday, July 07, 2011

Thunderstorm Activity Down Considerably Yesterday


The 0000 UTC (5 pm MST - above) regional radar chart from NCAR indicates considerably diminished thunderstorm activity yesterday. The strongest storms in southeast Arizona were the two cells over the San Pedro Valley and the eastern Catalinas/Redington Pass area. The Redington Pass storm moved into the northeast fringe of town while it was decaying. It sent a strong otflow across parts of town - the east winds pushing the afternoon's dirty air back toward Phoenix. Here at house we had some wind, a nice rainbow, and a slight spit of rain - Trace. The 0000 UTC Tucson sounding, below, indicates slight CAPE and considerable CIN atop the rebuilt boundary layer, as well as a continuing poor, vertical wind shear profile. The sounding was about 5 mm too dry wrt GFS data, making the exact situation unknown regarding CAPE and CIN. Clearly the marginal sounding and anvil shading combined to keep the storms at higher elevations.


The Pima County ALERT network only had 17 stations with rainfall (less than 20% areal coverage) and the sites with rain were in the Catalina and Redington Pass areas. The map below shows most of the rainfall reports, as well as the heavy amounts along Redington Road - 0.55" at Italian Trap, 0.98" at White Tank, and 1.06" at Bellota Ranch Road. Most of the runoff went toward the San Pedro apparently, since the Rillito was not running this morning. The 20 ALERT gauges in the Tucson metro area had 1 station with rain - that was the station with 0.12" near the confluence of Tanque Verde and Sabino Creeks.

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