Saturday, February 26, 2011

WRF Forecasts Light Snow Across Tucson

The U of A Atmo version of the WRF (WRF-GFS run at midnight last night) forecasts a very distinct and strong frontal passage across metro Tucson between midnight and 1 am Sunday morninig the 27th (top graphic). The total forecast model precipitation ending at noon Sunday (second graphic) indicates widespread precipitation with heaviest amounts at higher elevations (0.4" at TUS). Interestingly, the model forecast total snowfall by noon Sunday (third graphic) forecasts light snow across the Tucson metro - except here at house which is in the lowest elevations of metro area along the Rillito! The model forecast Tucson sounding for 3 am on Sunday (bottom graphic) shows a cold, saturated environment below a very low tropopause - note surface temp forecast of 33 or 34F. So, the WRF forecasts a very wild early morning here in Tucson, with the model forecasting the event locally (except in mountains) to have ended by midmorning.
The cold, 500 mb low is now over land in northern California, northwest of Reno, Nevada, with coldest temperatures at its core a bit colder than -36C, according to the morning analyses - 12 UTC Saturday February 26, 2011.

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