Monday, August 24, 2009

Downturn Begins A New Week


Yesterday was marked by storms that primarily stayed on or near the mountains. Only 39 of the 93 ALERT stations had measurable rainfall and these were the higher elevation stations. The mountain storms produced locally heavy rains - 11 ALERT stations had a half inch or more. Three stations in the Redington Pass area had more than an inch - that storm was visible from the house and produced a cool easterly outflow of about 30 mph here - otherwise a day with only anvils overhead. The Rucker RAWS station in the Chirachuas reported 1.98" for the highest amount I found this morning.


The piece of the 500 mb short-wave that came ashore last evening was stronger than expected and it is moving across Arizona today. Vertical wind profiles have become southwesterly and the dry air aloft is deepening. Precipitable water profiles continue a slow downward trend. The Tucson sounding this morning indicates a bit of CAPE for low elevations, but more drying or slight warming in middle levels would wipe that out.


The NAM has been too wet for this event, and I suspect that will again be the case today. Storms will again be mostly on mountains in eastern parts of state. Steering flow remains bad for low elevation regions - storms occur at the house under this kind of flow only if they develop nearly overhead.


The week begins with drying, and then there will be several features rotating around the 500 mb anticyclone as it shifts westward. Looks like the NAM predicted TS will track too far west to trigger a surge. It also appears that the S/W coming ashore today may try to track all the way around the anticyclone and come back our way from the east later in the week.

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