While attention in Tucson is on record high temperatures over the next several days, and an eventual increase in moisture, the screaming message from analyses and model forecasts is that there will be a weak or nonexistent mid-level capping inversion by the time the moisture arrives. The 500 mbar temperature this afternoon was -5 deg C. It will probably creep up to -3 C or so at times over the next two or three days. But by Tuesday afternoon the GFS run from 18Z has 500 mbar temperatures around -8 C in a pocket around Tucson. There is also at the same time a bit of an easterly wave racing along the southern extremity of the 500-mbar high. I like to loop the model soundings for Tucson at the NCEP models site. The GFS would have a SW-NE oriented line of storms moving through the Tucson region Tuesday mid afternoon, with measurable rain to the southwest, and significant cooling in Tucson by 5 pm. Things may not work out that way, but it is one of many interesting possibilities.
