Tuesday, June 20, 2017

Very Hot But Interesting Day On Tap

Third hottest day on record here in Tucson yesterday at 115 F. Was very warm at sunrise (one of my warmest morning walks ever), with hazy, dusty, smokey skies and lingering clouds.

Middle and high level moisture increases have brought PW up to around an inch and the 6 UTC forecasts from Atmo's WRF-GFS model are indicating an interesting day, even with the very high temperatures. The forecast of composite radar echoes above is valid at 06:00 pm MST this evening. The model forecasts storms to surround a low-elevation, metro donut hole. The forecast sounding (below) is valid at 03:00 pm. The sounding has just over an inch of PW and mixed layer CAPE greater than 500 J/Kg. Cloud base would be way up at about 550 mb indicating strong potential for local downbursts.

The 10m wind forecasts from the model (above valid at 05:00 pm and below valid at 08:00 pm) indicate strong outflows across the metro area before dark, with some winds to our north and northeast possibly reaching severe levels.

However, the model forecasts little cooling with the outflows - 2m T forecasts here are valid at 03:00 pm (above) and at 8:00 pm (below). Airport does drop from 111 to 95 F and the accompanying increase in RH would make for a miserable evening. Time will tell how all this actually evolves.

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