Tuesday, September 09, 2014

Quick Look At Today

Both the Phoenix and Tucson metro areas had record breaking rainfalls yesterday and I hope to do a couple of more technical posts about the events later today. Below is plot of the phenomenal Phoenix Rainfall Index for yesterday - it is really quite amazing. There were hundreds of high-water rescues and, sadly, two people drowned in flooded washes in the Tucson area. More detailed descriptions and many photographs are at Art Rangno's blog - link at right.

The sounding from TWC this morning (above from Univ. of Wyoming upper air site) is much different than was yesterday's. Dry air has intruded from the southwest at 700 mb and up, resulting in much reduced PW and very limited CAPE, due to warm air in middle levels.  Trough at 500 mb approaching from the west through next 36 hours produces a transition situation with westerly flow interacting with residual, subtropical moisture in low-levels. PW values remain considerably higher to the west. The latest NAM forecast of 850 mb, with PW, valid at 5 pm MST this afternoon is shown below. The shear and CAPE will be more conducive to strong storms across central and northern portions of Arizona this afternoon.

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