Mixed Signals

Nice view of Catalinas from campus just after sunrise this morning.

The 500 mb analysis this morning (above) continues to be a chopped up mess due to weak height gradients and light winds. Main anticyclone center appears to be over eastern Oklahoma. There are several weak troughs and inverted troughs, and even a weak cyclone over the lower Colorado River Basin. The main feature of interest though is the weak disturbance moving into southern Texas. This feature is forecast to move steadily westward and would begin affecting our area by Wednesday, if the forecasts verify well.

The morning sounding from TWC/TUS (above) is also a mess with a cool surface layer overlain by a meso-downdraft  signature that extends up to 600 mb. I can not forecast an evolution of this sounding during the day that would have much convective potential.

The 06 UTC WRF-GFS forecast (above for rainfall through midnight) develops storms and very heavy rains in the metro area. However, the 09 UTC WRF-RR forecast for precipitation through midnight (below) forecasts essentially a large donut hole across eastern Pima and Pinal Counties.

At bottom (from NWS Forecast Office web page) is an excessive rainfall outlook for today - this forecast originated at the national Weather Prediction Center in DC.

Definitely mixed signals - I favor the the WRF-RR (below) based on the really ugly morning sounding. Of course time will tell.