Saturday, May 30, 2015

Back-Door Front Approaches Southeast Arizona

A back-door front from the Plains is just pushing into the southeast corner of Arizona. The above surface analysis for 12 UTC this morning is from the Weather Prediction Center of the NWS. At 12 UTC the front was actually further west over southern New Mexico than has been analyzed.

Moisture at low-levels increases behind the front and the 06 UTC run of the WRF-NAM at Atmo just eases the air from the east across eastern Pima County tomorrow. The graphic above shows the forecast of PW valid at 11 am MST tomorrow morning (May 31st). The PW is forecast to increase to nearly an inch from this morning's value of just over half an inch. The skew-T forecast by the model for TWC at 10 am tomorrow morning (below) shows the cooler and more moist air from the surface to 850 mb, with today's old boundary layer above to about 600 mb. 

The front does not survive long, as westerly winds tomorrow afternoon push what's left of the Plains air mass back toward the east. The model does forecast some very light sprinkles tomorrow afternoon over in higher elevation parts of Cochise County.

As for today, the big question is whether the high this afternoon will hit or break 100 F - yesterday's heat peaked at 99 F at the airport.

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