The current trend continues to be driven by the various models' forecasts of available moisture. Shown here are the 06 UTC WRF-GFS forecasts of PW valid at 05:00 am MST (above) and at noon (below) for tomorrow on the 5.4 km grid. The AR from west-southwest of San Diego now is forecast to weaken very rapidly and apparently leads to the drier trend.
The high resolution WRF forecasts valid at midnight tomorrow night both are forecasting little at the the airport (GFS version above and NAM version below). However, the WRF-GFS sounding forecast for Tucson (second below and valid at 10:00 am tomorrow morning) appears favorable for showers and perhaps even thunder, so the WRF variants may have gone a bit too dry. These models continue to forecast some gusty winds with this system, particularly tomorrow in Cochise County. All we can do now is watch how things evolve.