Very Warm And Dry

Another very warm day here in Tucson with cloudless skies, as per above view of Catalinas from U of A campus. Temperature at 3 pm at TUS was 90F with the RH down at 8 %.  That's a diurnal swing of 50F here at the house today, since morning low was 40F. Big changes are on the way for the weekend however

The morning 500 mb analysis is shown above, indicating an anticyclone over southern Nevada with heights a bit over 5880 m - height here at Tucson this morning was 5870 m. The ECMWF 500 mb forecast valid at 5 am MST on Sunday the 11th is shown below. Very large height falls forecast to occur as the short wave currently in the Gulf of Alaska digs southeastward and sharpens up. The model forecast heights at TUS appear to be about 5580 m - a fall of almost 300 m. For certain we'll have wind and perhaps dust as the system approaches late in the week. The chances for showers at low elevations appear somewhat iffy at this time. But, it will certainly feel like winter has come in for a weekend visit, with a distinct frontal passage late Saturday.