Last evening's precipitation event was widespread across eastern Pima County - areal coverage across the ALERT network was between 90 and 100 percent. The uncertainty is caused by some higher elevation stations receiving only snowfall, which is not measured by the system. The heaviest amounts of rain were recorded in the Redington Pass area (above - 24-h rain through 5 am MST this morning). Amounts over low elevations of the metro area were quite light - 0.06" here at the house.
The strongest wind gusts I found for yesterday afternoon were at middle elevations, e.g., Pioneer Airfield (4767 ft MSL) gusts to 49 mph and Douglas (4154 ft MSL) gusts to 47 mph. Higher and lower elevations tended to have gusts around 30-35 mph. Early this morning some of the stations in Cochise County have been reporting light snow.
On tap are more cold, frosty December mornings. Shown above is the early WRF-NAM forecast of surface conditions across metro Tucson valid at 6:00 am MST tomorrow morning (Saturday, December 27th). Model forecasts the temperature at many spots to fall into the upper 20s - means that lows here along the Rillito wash will likely be in the 15 to 20 F range.
The model forecast of the sounding (at TWC on campus) shown below is also valid at 6:00 am. The very cold and stable surface inversion layer is the layer within which weak, cold air drainage flows develop within and near the Rillito wash.
The ECMWF continues to forecast another weather event for the Southwest for the New Years holiday next week. I've shown here the model's 500 mb forecasts for 96-hours and 168-hours (these are valid at 5:00 pm MST on Monday and then at 5:00 pm on New Years Day. The model forecasts a very strong short wave and attendant vorticity maximum to dig southward on the east side of the Pacific ridge and to evolve into a very cold, closed low over southern California on New Years. Snow levels with this system will drop to very low elevations.
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