Wednesday, August 25, 2010

Chopped Up Pattern Today

This morning strong easterly winds continue near the surface. The Tucson morning sounding (top) shows an onion shape indicating serious mesoscale contamination. So the nice increase in middle level winds indicated may be due to the MCV that is passing by this morning, and a return to L/V may occur this afternoon (the Marana profiler already shows a weakening of the middle level winds). The Ft. Huachuca wind profiler indicates strong southeasterly low-level winds, with the flow becoming westerly at 500 mb. So, a chopped up pattern with several smaller scale features wandering around that aren't captured in the larger-scale analyses (see 500 mb chart middle). The 500 mb NAM forecast indicates another weak shortwave around southeast Arizona this evening, with the more pronounced one translated out to western part of the state. Surface dewpoints are much lower across the border in New Mexico. I am going to assume that the downslope winds will prevail today and that storms, if any, will be on higher mountains, as the lower levels dry out some. Tropical storm Frank has strengthened some (see bottom image) and is expected to become a hurricane today. Frank's track is forecast to take the storm up southwest of the tip of Baja, and then it will begin interacting with the next Pacific trough. Both the GFS and ECMWF are now forecasting that the trough will come ashore and not pick up Frank, leaving it to head west out into the Pacific. We should keep a close eye on Frank's track the next several day's. Since I feel quite snakebit, I'll keep an eye on the cloud masses still to our east and south and try to follow the mescale swirls during the day today.

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