Friday, June 26, 2015

Thunder Again

Thunderstorms did move across parts of the metro yesterday afternoon. View of Catalinas above at 6:00 pm MST shows how very high the cloud bases were. Radar image below from just before 6:00 pm shows a strong storm cell (centered over word "TUCSON") that produced a strong outflow that moved across much of the city. The airport recorded a severe gust to 60 mph from this storm; Davis-Monthan AFB had 47 mph; and here at house I estimated 50 mph just before 6:00 pm. We had thunder for second straight day and there was a brief spritz of light rain that gave us 0.01" - so, the summer thunderstorm season has now begun along the Rillito.

Rainfall amounts from the storms were very light. Across the ALERT network 33 sites had rainfall of .04" or more. Maximum amount reported was only 0.24" at two sites. The rain here at house was just enough to wet the courtyard flagstone for a brief period, but the ground along the Rillito this morning remains powder dry.

As the WRF model runs had predicted, most of the thunderstorm activity remained to the east and south of Tucson - the above plot of CG flash detections (from Atmo and Vaisala) is through 11:00 pm yesterday. The 00 UTC sounding from TWC (below) indicates that moderate convection had eaten away the morning inversion above 500 mb; that there was a sliver of CAPE over town; and that the WRF-GFS forecast of the afternoon thermodynamics was better than that from the NAM version. The wind profile below 400 mb remained essentially light and variable - so a real mixed-bag of a day.

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