Thursday, February 20, 2020

Second Weather Event Of February Looms

Snowy afternoon in the Ben Nevis Range of the Scottish Highlands - above. Locally, it appears that our second precipitation event of February is developing for Friday night and Saturday.

These three forecasts are from the 06 UTC run of the WRF-GFS model at Atmo. Above is a forecast for the 500 mb level valid at midnight on Saturday. Cold, closed low centered over northwestern Arizona forecast for that time. Forecast skew-T plot below for Tucson at noon on Saturday - PW has increased in the forecast to 30 mm (from current value of a bit less than 10 mm), with a bit of low-level CAPE. Second below is forecast for precipitation amounts through 5:00 am MST on Sunday morning, the 23rd. This, if forecast verifies, would be a significant event for much of Arizona, including the Tucson metro area.

The bottom three forecasts are from the 06 UTC GEFS forecasts. The wind speed plumes above indicated strong and gusty winds ahead of the system on Friday and then again on Saturday during the precipitation. 

Plumes below also show a large jump in PW beginning this afternoon and peaking during the morning on Saturday. The GEFS forecast for QPF at the airport (bottom) indicate a very focussed event lasting from around 5:00 pm tomorrow through 5:00 pm on Saturday. The GEFS forecasts may be a bit faster than the WRF-GFS forecasts, but it should be an interesting start to the weekend, weatherwise.

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