Monday, August 17, 2009

Clear, Dry, and Hot


Delayed by yard work this morning. Skies over Arizona are as clear as they can be and it continues clear, dry and hot in the afternoons. The 1615Z visible image shows only a smoke plume from a fire about 13 miles southwest of Flagstaff - the Taylor fire.
The TWC sounding is unbelievably dry this morning at 850 mb with a 50+C T-Td spread and just 0.27" of precipitable water. Phoenix in contrast has a more realistic spread of 29C and precipitable water of 0.52". Of course these kind of values remain terribly low for August and the subtropical air mass has been pushed south past Guaymas this morning.
The 500 mb anticyclone has two nearby centers of circulation this morning - one over the Pacific just west of central Baja and the other over southeastern New Mexico. The morning NAM does not seem to have either of these centers initialized very well. The NAM forecasts are more dry than were yesterday's runs and tend to keep us under the influence of the Pacific anticyclonic circulation until late in the week. So goes the failed monsoon of 2009.

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