Yesterday was mostly hot (TUS high 108F) and dry, but some isolated showers and thundershowers got going late, after a moist outflow from the west pushed back across Tucson. At 5:30 pm none of the 93 ALERT sites had any recorded rainfall. However, this morning's data show that 8 sites had measured very light amounts during the evening hours - areal coverage of a bit less than 10%.
The above webcam view of the Catalinas at 6 pm MST yesterday shows a very light shower on the right side of image. This shower was just to the north of the house - we had not a drop here and no thunder or lightning.
The time series of T and Td from Atmo is above - note the outflow around 5 pm that kicked the dewpoint up from middle 40s to upper 50s, and then a second outflow around 8:30 pm pushed it into the low 60s. Activity yesterday was mostly as predicted by the models, with most significant storms to the west and northwest.
This morning's sounding (above from Univ. of Wyoming) shows a shallow, cool layer near the surface and a deep, old BL above. There will be a bit of CAPE again this afternoon. Any convection will be very high-based with potential for producing gusty winds. The deep easterlies will dry things out again, but there may be more outflows sloshing around.
The early WRF-GFS (and NAM) again forecast significant storms to occur out to west and northwest (above is 7 pm WRF-GFS composite radar), where the moist and drier air butt heads this afternoon. The WRF-GFS doesn't let moist low-level air push in across metro area from the west until 8 pm or so. So, mostly another hot and dry day over southeast Arizona as August winds down.
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