Very Complicated Situation Today

Brief overview of the situation today follows:

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Sounding at Tucson this morning (top) indicates little to no CAPE; as did the sounding last evening before the thunderstorms at the airport. However, wrt GPS PW the sounding last evening was over 1 cm too dry and this morning's sounding is a bit more than 5 mm too dry. So, throw out all those indices computed by the sounding analysis software. There appear to be enhanced southeast winds at low-levels (both Tucson and El Paso) affected by both outflows and a decaying, backdoor front to the south. The Guaymas sounding this morning has moistened nicely and shows a good surge signal, enhanced by very strong outflow from the strong MCS that collapsed just to the south this early morning, in low-levels. Around the area, GPS PW values are: Yuma 19 mm; Tucson 32 mm; and Hemosillo 51 mm. So, highest moisture values extend northward from GoC into southeast Arizona. The vertical wind profile is not great for organized storms with winds from 600 mb up being from the south-southwest at 20 to 30 knots, indicating that anvils will try to spread out directly ahead of storms. this is a poor profile for rainfall in this part of town - unless, as I noted below, something develops very close to the south. Convective cloud bases indicated around 600 mb or so, with threat of gusty winds remaining because of the deep, hot boundary layer.

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At 500 mb, the morning NAM analyzes (middle graphic) a nice inverted trough over the southern half of GoC, with a convectively enhanced vorticity maxima (see IR image of MCS activity over south GoC at 08Z this morning) southwest of Hermosillo. The Pacific trough remains along the California coast, and the center of the 500 mb anticyclone has slipped just south of the border in the Southwest. Further south, TD Seven E is spinning fairly vigorously south of Cabo Correntes - this system is forecast to become a TS and to move off to the west, passing southwest of the end of Baja. Many aspects of the current setting look like it's September rather than early August.

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The NAM appears to forecast an afternoon and evening similar to yesterday and holds off the increased moisture and heavier rains until tomorrow. I'm inclined to think that better moisture may be in southeastern Arizona by evening and that there should be another increase in activity relative to last two days. However, the details of today are complicated by the cool outflows that have affected the area, and by clouds and even some midmorning storms. Thus, a very difficult day to forecast for specific points.