Sunday, June 28, 2015

Quick Look At Today

Pattern remains stagnant with nasty 500 mb anticyclone centered southwest of Salt Lake City with core heights of about 5960 m. Moisture has moved around the west side of the anticyclone and extends from west Mexico to the Canadian border. Really quite amazing for June. Forecast from latest NAM for 06 UTC tonight indicates little change, and weak vorticity maxima far removed from southeast Arizona. Little forcing for vertical motion, leaving storm initiations relying upon local circulations related to complex terrain.

Mike Leuthold has already done a discussion based on the 06 UTC WRF forecast runs - those with access should refer to his analysis.

Above is the TWC morning sounding, which I have modified for mid-afternoon conditions. Moisture in the well-mixed BL seems to have increased a bit, offsetting a bit of warming around 500 mb. The lifted BL parcel this morning has theta-W of ~23 C - a fair value for more strong storms today (24 C and higher brings us our strongest summer storms). The wind profile is supportive of organized storms and the WRF forecasts take storms today far west into the low desert. The warm inversion aloft, above 500 mb, seems to have vanished for today. The culprit today would be upper-tropospheric subsidence, renewing the warm air aloft. However, I have scanned the nearby soundings at 400 and 300 mb and don't find any indications of warm advection, nor do any of the upstream soundings indicate the warm inversion. Another day whose outcomes will be determined by where the strongest initial storms develop and how they propagate.

Visible image below (from 1540 UTC) illustrates the remarkable moisture and cloud plumes over the west that I mentioned above.

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