Wednesday, July 16, 2014

Dry-Out Underway

The storms yesterday morning were the main show in town and brought locally heavy rains to western parts of the Tucson metro area. The plot of CG flash locations above (24-hours through 05 UTC on the 16th of July) indicates much diminished storm activity across southeastern Arizona. The MesoWest plot below shows rainfall reports for 24-hours ending 7 am MST this morning. Apparently the afternoon rains off to the southeast of Tucson were not associated with storms producing lightning.

Across the Pima County ALERT network 49 of 92 sites had rainfall yesterday and these were mostly in the western half of the network. Here at the house morning storms brought only 0.11". But in the ALERT network 17 sites had 1/2" or more, 8 sites had 1" or more, and one station reported over 2" of rain. TUS had 0.56" but DM had only .29" and Atmo reported only 0.2".

The dry-out the models have been forecasting is underway this morning. Although the TUS sounding is still very moist with CAPE, the morning soundings from Yuma (above) and Phoenix (below) show considerable drying. The dry air at Phoenix is below 700 mb but winds in the dry layer are west to northwest, bringing that air in our direction. Surface observations from MesoWest indicate that dry air at the surface extends east of Ajo and reaches into the west metro portions of Phoenix.

It is likely that any storms in southeast Arizona today will occur to the east and south of the Tucson metro area. The next couple of days will be hotter and dry, and the next key weather question will be that of how long will it take for low-level moisture to return.

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