Monday, February 23, 2015

Another Moisture-Starved Event For Southeast Arizona

Closed low at 500 mb this morning centered over Lake Tahoo (above is 06 UTC NAM 500 mb forecast valid at 12 UTC this morning - Monday, February 23rd). This feature will weaken and open toward the east as it moves across the Southwest during the next 48-hours.

Values of PW have increased to around 1/2 to 3/4 of an inch across lower elevations of southern Arizona, Analysis of total PW from CIRA (below) is valid at 12 UTC this morning and shows that values of an inch or more continue to lurk to our south over Sonora.

The WRF-NAM forecast run from 06 UTC this morning moves a band of light showers and sprinkles across eastern Pima County around mid-day tomorrow - forecast of composite radar echoes above is valid at 11 am MST on the 24th. The forecast sounding for TWC (below - valid at 10 am tomorrow) indicates very shallow low-level moisture, but does have a nice little area of CAPE below 700 mb. Showers in this layer would be very effective in getting a little rain to the ground because of the low cloud bases.

The WRF-NAM forecast for total accumulated precipitation through 5 pm MST tomorrow is shown above - model does not forecast much for southeastern Arizona. But through this winter its precipitation forecasts for southeast Arizona have been a bit low for the weaker systems.

Northern Arizona is having a wet storm with snow and some rain - Flagstaff has already measured 0.91" and Page has measured 0.69" of water equivalent, with mostly snow up there.

Meanwhile, off to the east, the DFW metroplex and north Texas have been hit by a significant sleet storm that is causing Monday morning chaos. Webcam shot below is of one of the expressways in Dallas. Over a thousand flights have been cancelled this  morning at DFW - glad I'm not flying today!

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