Saturday, July 25, 2015

Significant Downturn Continues Into Weekend

Almost a completely down day yesterday, as per the early WRF model forecasts. The plot of detected CG flashes (above, from Vaisala and Atmo for 24-hours ending at midnight last night) shows a few flashes in the east end of Catalinas and also down in the Santa Ritas, with most activity in Cochise County. Across the ALERT network only 4 sites had very light rainfall during past 24-hours, so yesterday and last night were essentially zero POPs periods for almost all of Pima County.

There is abundant debris cloudiness from Mexico at middle and high levels across all of southeast Arizona this morning (visible image below from 6:45 am MST). A quick look at this image would lead one to believe that we should be in thick of the action today.

However, the 12 UTC sounding from TWC (skewT plot above from NCAR RAL) shows dry air within most of old boundary layer, i.e., up to 700 mb - only moisture is holding on near surface. The morning Phoenix sounding (below for 12 UTC) is even more dismal with very dry air below 700 mb. Note the northwest winds at 10 to 20 mph up at Phoenix, which will be pushing this drier air our way. So, it is not surprising that the model forecasts this morning indicate only isolated thunderstorms in Santa Cruz and Cochise Counties today.

While June was interesting, July has proven to be very depressing here in the local area.

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