Mostly Winds And Dust Yesterday

There were a number of severe thunderstorm reports across the West yesterday (above plot is of reports received at SPC), showing a classic "ring of fire" pattern around the mid-level anticyclone. Here in southeast Arizona there were probably many more events than were reported to SPC. Davis Monthan AFB had a gust to 64 mph as the wind and dust moved across town around 9:30 pm MST. The paper this morning indicates numerous lines down and power outages, mostly on the east side. The airport carried a gust to 51 mph. Here at the house I estimated only 30 to 40 mph. Most of the BLM RAWS stations in this part of the state had gusts over 50 mph. The WRF 12 UTC morning runs at atmo yesterday did an excellent job forecasting the severe wind event.

Mike Leuthold's tailored version of the WRF also did an excellent job forecasting the big decrease in precipitation probabilities yesterday (see earlier post below). The official forecasts of 50 to 80% for last evening were considerably too high. Only 11 ALERT stations (12%) had rainfall after 6 pm last evening. These reports were along the eastern edge of the network and were very light, generally a tenth of an inch or less. So, a serious downturn in the rainfall - I noted here at house that the soil was again powder dry by noon yesterday.

This morning PW is down some due to fairly brisk, low-level, downslope winds from the east to southeast. The morning sounding is chopped up again, but the early WRF-GFS forecasts small amounts of CAPE by afternoon at lower elevations. The forecast of composite radar echoes valid at 5 pm MST this afternoon (above) again indicates storms mostly to the east, with some just clipping the southeast corner of Pima County. However, the model forecasts the surface winds to become westerly this afternoon (below is forecast of 10-m winds valid at 5 pm). This puts a strong convergence zone over the metro area as another outflow comes in from the east. So, a tricky forecast for later today. The model forecast of total rainfall through 6 am tomorrow morning (graphic down at bottom) keeps most of the metro area dry, with the rains mostly to the south and east. Will need to keep an eye on how the moisture and winds evolve during the day.