Wednesday, July 28, 2010

Active Storm Day Yesterday

Yesterday was an active storm day over many parts of southeastern Arizona. Storms developed early during the mid-to-late morning over higher terrain. Had a shower here around 2 pm and then light anvil rain later in afternoon. The Pima County ALERT network recorded rainfall at 64 of the 93 gauges - so a very definite up-turn day with high POPs. The storms did tend to stay at higher elevations and few gauges in the actual metro area recorded rainfall, and those that did had very light amounts. The heaviest storms skirted south of Tucson along higher elevations near Green Valley - as is often the case, especially with light steering flow. Here at house we had 0.08", which was a high total for the low elevation stations. Notable amounts during past 24-hours: 17 ALERT gauges had 0.50" or greater; 8 gauges had 1.00" or greater; and two ALERT gauges had more than 2.00"; Douglas reported 1.06" and Mt. Hopkins had 0.76." The Tucson NWS radar at 3 pm indicated a very large storm south of the city - this storm had tops well above 50,000 ft and produced wind damage near Sahuarita, downing poles and power lines. An hour or so earlier, a strong storm near Sonoita produced a rope-like tornado that was videotaped and shown on TV news this morning. The large storm shown on radar above produced a cool, strong outflow that moved north across the city, resulting in the low stratus band along the Catalinas shown in bottom image.
This morning it is very humid across almost all of Arizona with dewpoints in the upper 50s and 60s, even at high elevation stations. The GPS precipitable water data indicate 50.5 mm here at Tucson and 56.4 mm at Phoenix - very high values for here. The surface observations at Tucson indicate that it is 5F cooler than it was 24-hours ago; Td is up by 5F and the SLP is up by 3.5 mb. Similar changes were also noted at Phoenix this morning. Was a very sweaty walk at sunrise. I did see something that I have never seen before - I observed a hawk trying to grab a bat in flight. The bat got away. Even though it is late in July, I have yet to observe any spadefoot toads out and about - just not wet enough yet in this part of town to produce the large puddles of standing water that bring them up.

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