Brief Overview of Conditions This Morning (Tuesday 4 Aug 2009)
The strong complexes of storms along the border (02Z IR image) last evening pushed outflows into southeastern Arizona and also squeezed on the GoC air mass sending a push of more moist air northward into southwestern Arizona. The net result is that surface dewpoints (roughly west and south of line Douglas to Safford to Kingman are up 7 to 11F relative to this time yesterday. The soundings this morning at Tucson and Phoenix show that the increased moisture extends to about 850 mb and a VAD out at Yuma shows south-southeast winds of 15 to 20 kts extending to about 3000 ft MSL. So, finally at least a modest increase in moisture (note that Atmo’s GPS PW time series are down and have been since last evening).
Manning Camp at 8200 ft MSL in the Rincons measured 0.04” in anvil sprinkles last evening. This is only the second time a gauge in the Alert network has measured rainfall for the period that began on Sunday July 26th.
Although the moisture is up, the soundings continue to indicate a difficult situation if storms are to get going at lower elevations. The data at Phoenix and Tucson show a dry-hot residual boundary layer above the new moist layer, that extends to above 600 mb. So this morning’s new cooler and moister surface boundary layer will need to continue to moisten and deepen and not mix with the old boundary layer aloft. However, winds are northwesterly to northerly and fairly strong in the elevated layer. If a surface boundary layer with moderate CAPE can maintain itself today (which I doubt), then a good outflow kick from higher-elevation storms could shift the activity into the deserts. My estimate is that the afternoon boundary layer will be well-mixed at 7 or 8 g/kg which gives a small amount of CAPE that would have to contend with the warm inversion that exists around 450 mb. So, a very complicated, but more interesting, situation today.
Morning NAM not available. I note that winds seem to have broken through already here at house since I wrote above and are from the northwest.
The strong complexes of storms along the border (02Z IR image) last evening pushed outflows into southeastern Arizona and also squeezed on the GoC air mass sending a push of more moist air northward into southwestern Arizona. The net result is that surface dewpoints (roughly west and south of line Douglas to Safford to Kingman are up 7 to 11F relative to this time yesterday. The soundings this morning at Tucson and Phoenix show that the increased moisture extends to about 850 mb and a VAD out at Yuma shows south-southeast winds of 15 to 20 kts extending to about 3000 ft MSL. So, finally at least a modest increase in moisture (note that Atmo’s GPS PW time series are down and have been since last evening).
Manning Camp at 8200 ft MSL in the Rincons measured 0.04” in anvil sprinkles last evening. This is only the second time a gauge in the Alert network has measured rainfall for the period that began on Sunday July 26th.
Although the moisture is up, the soundings continue to indicate a difficult situation if storms are to get going at lower elevations. The data at Phoenix and Tucson show a dry-hot residual boundary layer above the new moist layer, that extends to above 600 mb. So this morning’s new cooler and moister surface boundary layer will need to continue to moisten and deepen and not mix with the old boundary layer aloft. However, winds are northwesterly to northerly and fairly strong in the elevated layer. If a surface boundary layer with moderate CAPE can maintain itself today (which I doubt), then a good outflow kick from higher-elevation storms could shift the activity into the deserts. My estimate is that the afternoon boundary layer will be well-mixed at 7 or 8 g/kg which gives a small amount of CAPE that would have to contend with the warm inversion that exists around 450 mb. So, a very complicated, but more interesting, situation today.
Morning NAM not available. I note that winds seem to have broken through already here at house since I wrote above and are from the northwest.
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