The NWS was certainly on track yesterday, ignoring the high-res model forecasts during Saturday night and continuing to emphasize the heat for Sunday. High temperatures at airport beginning Thursday and going through yesterday have been: 107, 107, 110, and 106 F.
The huge MCS forecast by the 06 UTC WRF-NAM developed, but was over northern Sonora this morning rather than southeast Arizona. Plot of CG flashes for last 24-hours through 3:00 am MST this morning (above from Vaisala and Atmo) shows the only lightning in eastern Pima County was over west end of Catalinas very early yesterday morning, and that yesterday afternoon and last night most thunderstorm activity stayed to east and south of Tucson area. The 5:00 am IR satellite image below shows two large MCSs over Mexico this morning. The 5:30 am composite radar chart (second below) indicated some light showers to the north of Tucson before sunrise. Only 1 ALERT site northwest of Catalinas reported rain during past 24-hours (0.04" before sunrise this morning).
The morning sounding from TWC (skewT below for 12 UTC, 17 August) was actually quite close to that predicted by the 06 UTC WRF-NAM yesterday (see previous post) with very high PW and substantial CAPE. Outflows were around but apparently unable to lift the near surface air to saturation and thus no significant storms in eastern Pima County. There are still some very light showers over Pinal County but today's 06 UTC WRF forecasts continue to keep showers and thunderstorms east and south of the Tucson area.
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