The big news yesterday was that the high in Tucson reached only to a relatively cool 98F. The storms and rainfall yesterday avoided the low elevation deserts - although there were widespread sprinkles and traces of rain. One of those days where the model day 2 forecasts proved a bit better than the day 1 forecasts. Across the ALERT network 40 sites (a bit over 40% areal coverage) had rainfall between 6 pm MST last evening and 7 am this morning - of interest was the complete lack of rainfall (0% coverage) across eastern Pima County during the 6-hours from noon to 6 pm. Most rain in the ALERT network during the night was 0.55" at Arivaca. The above image shows regional radar (from NCAR RAL) at 7 pm last evening. Storms that approached Tucson from the east decayed over the mountains - apparently outflows across Tucson were not strong enough to produce new storms at lower elevations. The 00 UTC Tucson sounding indicated no CAPE, however, comparison to GPS PW (below) shows that the sounding was nearly a half inch too dry - a seriously bad RRS sounding. So, it remains a bit of a mystery what the CAPE situation was last evening. The heaviest rains were along the Borderlands - Nogales had 1.49" (with a severe wind gust to 58 mph just after 7 pm) and Ft. Huachuca had 0.94".
This morning (7 am MST IR image below), a decaying MCS was present south of Douglas, and an intense complex of storms was active over the southern GoC. There was heavy morning cloud cover over all of southern Arizona and northwest Mexico at sunrise, indicating another forecasting challenge for today.
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