Saturday, July 20, 2013

Wet Atmosphere Yesterday But Suppressed Again Southeast Arizona


Yesterday was an active over much of Arizona - above plot shows 24-hour lightning strikes for period ending at 5 am MST this morning. Note that again there were almost no thunderstorms over all of southeast Arizona. Severe thunderstorms hit parts of the Phoenix and Las Vegas metro areas with damaging winds. The 5 am water vapor image below indicates an MCS over the lower Colorado River Basin. Here in eastern Pima County there were isolated showers - we had a brief shower and 0.04" of rain here at house during mid-afternoon. These were low top storms with warm rain and no lightning. Across the ALERT network there only 10 reports of light rainfall - so past three days have had ~10, 0, and ~10 % coverage of rainfall, hardly what one would expect with such a wet pattern.



Phoenix metro finally had some storms with rain - better amounts across the north part of metro - above is the Phoenix Rain Index (PRI) for 24-hours ending 7 am this morning. The PRI is accessible at: http://www.wrh.noaa.gov/psr/PRI/  The morning 12Z skew-T plot for Tucson is shown below - high PW but limited CAPE. Wind profile remains easterly with directional shear. But steering winds this afternoon may be stronger than upper-levels, letting storms leave their anvils trailing some to the rear. Better wind profiles for organized severe storms again will be toward northwest and west parts of state. Yuma has extreme PW this morning of >2 1/4 inches!

The early WRF-GFS run failed at Atmo - and Mike Leuthold is away this weekend. The crude resolution NAM model indicates a stormy and wet day for all of Arizona - rainfall amounts here in the southeast are greatest along the Borderlands, extending northward into Tucson area. The sounding indicates good potential for heavy rains and wet downbursts today - so the three days of suppression appear are ending today.


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