Sunday, July 22, 2012

Early Storms Quickly Head Off Toward Phoenix


Skies partly cleared fairly quickly yesterday (Saturday, 21 July 2012) and storms rapidly developed across the metro area around by 2 pm. The storms quickly organized into a large bow and sped off toward the west and northwest - above is Phoenix radar composite at about 3:30 pm MST. The storm left behind thick, trailing anvil, which basically shut things down for rest of the afternoon . There was limited activity to the east until late in the night. Rain amounts were more scattered than on Friday - 53 stations in the ALERT network had rainfall with 6 stations with a half inch or more. here at house there was 0.04", TUS had a trace, DM AFB reports 0.29" - Atmo station seems to have problems with yesterday's amount still showing for Saturday but with the plot indicating 0.10". The weakening storms raced into Phoenix around 6 pm with thick, blowing dust (Sky Harbor and Scottsdale airports both gusted to 51 mph). Rain was mostly spits and light showers however. An aside, the Vaisala RS-92 GPS sonde used at Phoenix is tracking very close to GPS PW measurements this week (below).



This morning there are heavy clouds and light sprinkles over the Tucson area and much of Arizona. (6:30 am MST visible satellite image above). The morning Tucson sounding (below) is very wet, with a bit less CAPE than yesterday due to warm, middle-level temperatures. Still an unstable sounding with potential for heavy local rain and wet microbursts. Key question is how much sunshine will materialize by afternoon - clouds appear heavier than yesterday. Also an issue is whether storms will develop off to the east today. The middle-level IT is gradually weakening as it moves slowly westward. Upper-levels have a weak deformation zone from overhead into west Texas. Sunshine and local forcing will play a large role in determining events this afternoon. Morning NAM forecasts an active day over all of southern Arizona. Atmo WRF-GFS again not available this morning.


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