Wednesday, July 20, 2016

More Of The Same?

Yesterday brought two rounds of storms and some rainfall around eastern Pima County. The afternoon round stayed mostly out of the metro area as per post below. Storms after dark moved in from Cochise County and provided a lightning show, but only light rainfall, as these storms also weakened at lower elevations. 

Across the ALERT network 60% of the sites measured 0.04" for the 24-hours ending at 5:00 am MST this morning - greatest coverage for quite a while, but amounts were generally light except for a couple of sites in the Catalinas. Evening event brought thunder and 0.01" here at the house.

For contrast/comparison here are the morphed and blended PW products from CIMSS (above) at Univ. of Wisconsin and from CIRA at Colorado State Univ. (below). Both are for 11 UTC this morning. Very high PW remains not too far to the south, just waiting for a real push. Amounts over 50 mm are shown in amber tints at top, but in red tones at bottom. Highest values above are with Tropical Storm Estelle.

The morning sounding plot for TWC (above) remains similar to last couple of days. However, mid-level temperatures have warmed a bit and the wind profile has weakened in speed, and become even more variable wrt the directions. So, another day favoring the higher elevations of southeastern Arizona.

Finally, out of curiosity, I looked at the GEFS plumes for next few days. The plot above is for CAPE, indicating a dry-down around the 23rd and 24th. The QPF forecasts below seem unresponsive to the fairly large CAPE fluctuations - some members manage, somehow, to forecast light showers at TUS, even during the period of almost no CAPE. The GFS (blue) forecasts a CAPE spike on the 25th.

As I had mentioned before, within a stagnant, summer 500 mb pattern, these forecasts probably mean little beyond days 1 and 2. All of this leads to the no-skill, default forecast of mostly climatological POPs at TUS for next seven days.

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