Saturday, January 23, 2021

First Significant Storm This Winter

Bit of morning sun hitting campus about 7:40 am MST today. Down at bottom is snow stake in Forest Lakes, Arizona, which is in the Rim Country east of Payson.

GFS forecast (from 00 UTC last evening) above valid at 11:00 am MST tomorrow indicating sharp, 500 mb trough approaching southern Arizona. As this system, and following short wave, impact Arizona, models continue to forecast a significant precipitation event. Plumes below from GEFS are for QPF at the airport. The members indicate measurable precipitation at airport tomorrow and then again Monday morning continuing through the day on Tuesday.
The plumes for temperature at the airport above indicate falling temperatures tomorrow through Wednesday, with drops of 30 F or more - given our fairly mild January to date, this will be a very pronounced turn toward more wintry weather.

In fact, the ensembles forecast a high probability of snow mixed with the rain at the airport (below) Tuesday night into Wednesday morning.

The 06 UTC runs of the WRF-GFS at Atmo are indicating very strong winds at the airport Monday afternoon (above), as second short wave approaches. The same forecast runs indicate light snow accumulations in the far east and south portions of the metro area during Monday night (below), which could bring some hazardous driving conditions, especially on two lane highways such as 83 south toward Sonoita, and 86 west toward Sells, as well as 90 south toward Sierra Vista. Will follow up re these possibilities tomorrow.

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