Monday, July 13, 2009

Ramblings on Monday Morning July 13, 2009

Virga showers came off the Rincons last evening around 6 pm or so with some winds and blowing dust along the Rillito. Mostly hot with high of 107F – 4 ALERT stations (in the Catalina and the Rincon mountains) reported a bit of rain yesterday.

Things I note this morning –

Moisture has gradually increased across south-central and southwest Arizona during past 24 hours (see GOES PW at 1300 UTC above). Yuma had a nice surge between 8 and 9 pm last evening, triggered by yesterday’s MCS, and there is a lot of cloudiness in the GoC this morning and another large MCS south of the GoC mouth.

This morning’s Tucson sounding shows increased PW but only a slight touch of CAPE, so more low-level moisture is needed, but the trend is good. Wind profile quite unusual with L/V winds entire upper-half of troposphere. Looks like lower-level winds will be from northwest this afternoon – hotter out that way but perhaps more moist also because of the surge. So, it looks like CAPE in the mountains and some meandering storms this afternoon. Strong downdraft environment so good chance for outflows off mountains. I'll watch the PW and Tds to see how much impact the surge has.

Upper-levels appear quite diffluent next couple of days, so if moist influx continues, tomorrow could be a more interesting day. The 500 mb anticyclone has remained locked over northwest Texas, and there is very warm air over southern New Mexico. Mid-level temps have remained relatively cool over Arizona. What’s lurking over northern Mexico?

As the S/W that’s onshore in the Pacific northwest moves over the ridge and digs south of Great Lakes at mid-week it will force a westward adjustment of the anticyclone. So, we might have increased activity as the large-scale goes through a period of transition.

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