High-based thunderstorms and light showers have been drifting around southeast Arizona during the night. Photo at top is from a bit before 6:00 am MST and is looking across Redington Pass toward San Pedro Valley. The NWS composite radar display just above is from 7:00 am, with strongest storm over near Kitt Peak. View below is looking south from Kitt Peak at 7:17 am. The CG flash density plot second below is for 12-hours ending at 7:00 am this morning (from weather.graphics and Vaisala). Even the puny Cb shown at top produced a few CG flashes.
The morning skew-T plot for TWC upper-air data (above) has PW of 1.23" (31 mm) and a moist layer from 600 to 500 mb that has some CAPE (see MU - most unstable) calculation above. The PW had briefly dropped to around an inch late yesterday, with dewpoints in the upper 40s F. Winds in middle-levels are are light as intense anticyclone edges westward toward our area.
The two WRF forecast runs from 06 UTC last night are quite different. The GFS version above forecasted the early am shower activity reasonably well, but forecasts little activity during the afternoon today (forecast of composite radar echoes above valid at 7:00 pm - model does forecast some nocturnal activity again tonight over mostly Cochise County). Note that the GFS forecast sounding for TWC at 6:00 pm has 26 mm PW and mixed layer CAPE of 20 J/Kg.
The NAM version (below, also valid at 7:00 pm) forecasts strong thunderstorm activity over eastern Pima County. However, the NAM forecast sounding for TWC at 6:00 pm has PW of 36 mm and mixed layer CAPE of almost 500 J/Kg, accounting for the differing forecasts.
My guess would be that the GFS version of WRF will play out closer to reality this afternoon and tonight.
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