Wednesday, June 30, 2010

Westerlies and Subtropics Do Battle Next Several Days




Complicated situation continues. Yesterday there were storms and convection around southeast Arizona. NWS Tucson radar finally back in operation between 6 and 7 pm last evening. Thunderstorms/showers with strong winds at Douglas, Ft, Huachuca, and Nogales yesterday afternoon. Measurable rain at 5 RAWS stations in southeast Arizona, but max amount only 0.15" at Rucker.
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This morning the downslope flow continues, but moisture has gradually inched upward with values around 1 inch across the lower elevations. The TWC morning sounding data only a bit dry but with CAPE indicated very similar to yesterday morning. The NAM forecast runs this morning (12 UTC 30 Jun 2010) show the Pacific trough and the remnants of Hurricane Alex doing battle with southern Arizona sitting right in the middle of the two features. Right now the NAM seems to indicate the trough dominating.
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The images above show: the morning sounding at Guaymas (top) to be quite dry with less than an inch PW; the sounding at Mazatlan (middle) which is quite moist with PW well over 2 inches; the current NAM 700 mb forecast for 12 UTC Friday, July 2nd. I think that the remains of Alex moving into the lower GoC will have a good chance of triggering a moisture surge up the GoC. The cloudy and damp push at 700 mb, perhaps with areas of thunderstorms moving off the Sierra Madres, will bring dramatic cooling over the lower GoC. Such cooling at 700 mb, particularly with storms, often triggers a surge. So, what happens over the south half of GoC may well hold the key to local weather for the rest of the long weekend.


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