Tuesday, August 02, 2016

Very Moist This Morning

Light showers were washing the west end of the Catalinas at about 7:30 am MST this morning. My morning walk was like being in a sauna.

Most of south-central Arizona was suppressed yesterday, with the exception of several thunderstorms on and near higher elevations. Phoenix and Tucson metro areas were devoid of CG flashes as per 24-hour plot above ending at 5:00 am (from Atmo and Vaisala).

The Pima County ALERT network seems to be operating normally this morning. Sector plot below is for 24-hours ending at 7:30 am. Across the network for this period 45% of the sites measured rainfall. There were 4 sites with over an inch and the 2.13" at Big Wash was the maximum amount - falling around 3:00 pm yesterday afternoon.

It's hard to interpret exactly what the coverages were for the 12-hour NWS forecast periods. There was rainfall both yesterday afternoon and then again early this morning. Many of the rain reports were in the high-elevation zones, while the low elevations were mostly suppressed. Appears areal coverage was probably highest for the yesterday period at high elevations.

The morning sounding plot for TWC (above from SPC) is amazingly wet with PW of two inches. The winds are light and variable through the entire troposphere - so a continuing threat of locally heavy rains, where storms do develop. The forecast models try to develop a weak - almost tropical warm-core - cyclone at 500 mb over eastern Pima County.

There were showers and a couple of thunderstorms across eastern Pima County at 7:00 am MST, as per the composite radar chart above. The 06 UTC NAM version of the WRF model was handling the location and timing of these showers better than the GFS version. The WRF-NAM forecasts showers and thunderstorms to continue through the morning and into early afternoon (composite radar forecast below valid at noon), with some impressive local rain amounts.

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