Friday, August 22, 2014

Mostly Suppressed Yesterday Over Southeast Arizona

One of the big "ifs" yesterday was how long the dreary and thick cloud cover would persist and, unfortunately, the answer was basically all day. As a result there was little in the way of thunderstorms and rainfall here in southeast Arizona. Only 14 of 92 ALERT stations had rainfall yesterday. The metro west sector of the ALERT network is shown above for the 24-hours ending at 7 am this morning (August 22nd). This was the most active sector and the 2/10s of an inch at the Santa Cruz and Ina site was the ONLY report of a tenth of an inch or more. Here at the house we had 0.01" from several brief periods of very light showers. So, a serious down day.

Most of the heavy storm activity was out in the southwest and west part of the state, as shown by the CG flash plot for the 24-hours ending at midnight last night. There were  numerous heavy storms out there and they were rotating rapidly around the mid-level cyclone - some radar loops were quite spectacular. The rainfall was also most significant west and northwest of the Tucson area - below is MesoWest plot of 24-hour rain reports through 7 am MST this morning.

The morning sounding at Tucson has some CAPE left this morning and there may be a bit more mid-level cooling before the 500 mb trough passes around noon. So, there will be a chance for isolated thunderstorms, mostly on and to east side of the mountains through early afternoon.

The models show marginal amounts of low-level moisture sloshing back and forth across southern Arizona for next several days. The global models are a bit at odds for the longer-term. The ECMWF keeps enough troughiness over the west to bring the summer storm season to a close. The GFS is bit more ambiguous, but definitely marginal for southern Arizona.

The wild card during the next 7 days will be Hurricane Marie - this is forecast to be a large storm and, even though it stays well west of Baja, the GFS forecasts a significant push of moisture into the Southwest associated with the storm. Will have to watch how this evolves.

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