Tuesday, September 15, 2015

Tuesday AM - Still Moist In Low-Levels

Thunderstorm activity was very much diminished yesterday over southeastern Arizona, as per flash density plot above (from Weather.Graphics and Vaisala) for 24-hours ending at 5:00 am MST this morning. Heaviest thunderstorm activity was off in far northwest Arizona and southern Utah, but with some strong storms in central Maricopa County. There were severe storm reports from Sky Harbor (damage on the airport) north to the Scottsdale Airport (gusts to 59 mph at Scottsdale and to 58 mph at Sky Harbor).

There were only 7 sites in the ALERT network with measured rainfall and amounts were light - we did get another brief storm off the Tucson Mountains and 0.06" here.

This morning dawned humid and hazy (as per 7:00 am view above) with moderate buildups all directions. Visible satellite image below is from 7:15 am.

The blended PW analysis from CIRA (above for 12 UTC) continues to indicate higher PW across south-central Arizona to our west. The morning sounding plot (below for TWC at 12 UTC) indicates moderate instability and CAPE present this morning, but dry air aloft has mixed down almost to 700 mb and temperatures are warm around 500 mb and above. It is another nice sounding, but the WRF forecasts for 00 and 06 UTC indicate some drying and and diminishing CAPE, as the BL deepens this morning. The net result is that all versions agree for this afternoon, with only very isolated storms forecast for Pima County.

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