Sunday, August 21, 2016

Sunday Morning Coming Down

I feel beat up after last 5 marginal storm days here in southeastern Arizona. Yesterday there were more storms around, but also lots of anvil shading with storms hugging higher elevations. The 06z WRF forecasts yesterday both tended toward too much storm activity in Pima County, although the NAM version was definitely more conservative than was the GFS version. The 24-hour rainfall map below (radar estimates adjusted by gauge data) is from Maricopa County Flood Control. It shows that most storm and rainfall activity at lower elevations was out along the Colorado River. There were several severe thunderstorms  in central and western Arizona.

Not much has changed today, except that MCS activity has helped spin-up a distinct MCV-type circulation that is moving northwestward over the lower Colorado River Basin. The 06 UTC WRF-NAM forecast of composite radar (2nd below) is valid at 1 pm MST today and is as active as the model forecasts for eastern Pima County.

The dismal large-scale pattern continues, with a westerly trough dominating the upper half of the troposphere over the Southwest - has been like this much of the month and begs the question of when did the deep monsoon pattern vanish? Several 300 mb charts are shown here - top 00 UTC on 9 August; just above 12 UTC this morning; bottom GFS forecast for 00 UTC 28 August. Argh - will a deep monsoonal pattern return at all this summer?

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