Tuesday, July 24, 2012

Considerable Downturn Yesterday


Thunderstorm activity over eastern Pima County was considerably less yesterday than on Sunday. Storms were slow moving and around the edges of town. The storm above at 4:30 pm MST was one of several cells just to the east and northeast of the house. We had lots of lightning and thunder, with outflow gusts of 40 to 50 mph, but the rain remained nearly stationary. So another day with spits and a trace. Across the ALERT network only 31 sites had rainfall during past 24-hours. There were only 4 stations with a half inch or more and two of these had over an inch. This morning heavy cloud cover has moved in from the northwest and there are morning showers occurring between here and Phoenix.



The morning Tucson sounding remains very wet and with potential for decent CAPE - appears there may be a bit of elevated CAPE present also. Almost no winds aloft again today. Remnants of the old 500 mb short-wave trough will hang over eastern Arizona today. Looks like a tough day for the models - the NAM forecasts widespread rain across eastern and southeastern Arizona from now through noon and then increases amounts and coverage in the afternoon. The early WRF-GFS forecast doesn't have the cloud cover initialized right and it forecasts widespread showers and storms in the afternoon. Both models focus on the east as drier and warmer air eases in from the west. The graphic below is WRF-GFS rainfall through midnight tonight.


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