Sunday, July 24, 2016

Another Outflow Across Southern Arizona

I have been out cleaning up tree and limb damage from the microburst event of four weeks ago and will just take quick look at the weather setting this morning.

Yesterday was another completely down day over most of southern Arizona, except for along the Borderlands and a storm in northeastern Cochise County. The 12 UTC WRF runs seemed better than those from 06 UTC. The plot of detected CGs below is from Atmo and Vaisala for 24-hours ending at 6:30 am MST this morning. There was no rainfall recorded across the entire ALERT network yesterday. Our really bad July continues.

There was significant thunderstorm activity in northern Sonora and IR image above was from 05:30 am. The storms have sent several moist outflows into southern Arizona. The current Doppler velocity image below is from Yuma at 1.8 degree tilt and indicates a fairly deep outflow with wind speeds of around 30 kt. During past few hours winds at Yuma have been from the south-southeast with gusts as high as 43 mph. Dewpoints there are running in the low 70s.

The morning TWC skewT plot above continues with about 1.5 inches of PW. The layer below 700 mb has considerable CAPE, but now has a capping, old elevated boundary above. So CAPE and CIN are doing battle again today. The 500 mb pattern is very chopped up and winds aloft are light and variable below 300 mb - not good, TS Frank has helped push high moisture into southern Arizona (below is CIRA blended PW analysis for 6:00 am) and values of PW are 1.5 inches and higher over a large portion of the area from Tucson west. However, other features just are not coming together well. Even though there is a weak inverted trough at 500 mb to our east, models continue to keep storm activity today along the Borderlands and into central Pima County - areas with higher elevations than the metro region. What steering flow there is would try to move storms from the Catalinas toward the metro - so that's a bit of a positive. Back to the yard mess.

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