20160824

Initializations

Relatively simple situation with clear skies over almost all of Arizona. The IPW errors are no larger than 2 mm, but unfortunately many of the SuomiNet sites didn’t make it into the data assimilation routine. We'll check on that later. Overall, confidence is high today.

12Z WRF GFS IPW initialization

Day 1

The Arizona is now on the back side of the trough and under northwesterly flow.

Storms form on the rim in the mid afternoon.

While northwesterly steering flow is generally not favorable for organized convection in the lower deserts, the storms are still somewhat able to “move” off the rim on outflow boundaries. Prime time in the deserts is between 4 and 6 PM today. Dust storms are likely in Pinal county.

The PBL is well mixed in Phoenix, 500 mb temperatures are a cool -11 C, and the vertical profile exhibits good directional shear. 12Z WRFNAM followed by 12Z WRFGFS.

Below, the 12Z WRF GFS shows a handful of isolated storms in the lower deserts around 6 PM.

12Z WRF GFS

It looks like it will be a little too dry in the lower levels and a little too warm in the mid levels for Tucson to see much activity.

Day 2

Isolated storms possible in southeastern AZ, mostly over higher terrain, with a few stronger storms in northern AZ.