Thursday, September 06, 2012

Suppressed Again In Eastern Pima County


The graphic above is the WRF-GFS 12 UTC forecast of total rainfall through 5 am MST this morning (Thursday 6 September). The forecast was quite accurate for eastern Pima County - forecast zip and zip is what we got. Another day with some forecasts being far too optimistic. Only 2 ALERT stations had very light rainfall - Mt. Lemmon and Arivaca. Across all of the main observing networks of southeast Arizona, I could only find 6 stations with rain - the 4 sites, in addition to the 2 ALERT stations, were all in Cochise and Graham Counties - Rucker RAWS in the Chiricahuas had 1.21" and Mt. Graham RAWS had 0.75". Our local Sky Islands were not effective generators of convection again yesterday - it's not clear why this was.


The WRF-GFS skewT forecast for Tucson at 5 pm MST yesterday is shown above - CAPE but also very significant CIN. Very light winds aloft and no outflows around at all, so another very moist BUT down day. The observed 5 pm TUS sounding (below) appears to actually have had less CIN, but still enough of a cap to keep things suppressed.


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