Another large MCS over Arizona!

For the second night in a row a large MCS has developed over Arizona, this one developing late and continuing active at sunrise.

I've attached several images: CLICK HERE

Fig 1 - IR image 0200 Z 26 Jul - This image shows three distinct MCSs, at least in the satellite view, that would force new convective development as their gust fronts converged over Phoenix.

Fig 2 - IR image 0630 Z 26 Jul - This image shows the resultant, huge cold cloud shield covering much of Arizona. The interesting thing about this MCS is that radar views indicate that 3 or 4 distinct smaller MCS are propagating a variety of directions beneath the over-arching anvil cloud. One of these actually moved eastward from the Phoenix Valley up into the Salt River drainage.

Fig 3 - A map of CG lightning strikes from 12z 25 Jul to 12z 26 Jul. The CG locations are color-coded by time. Close examination of the timing of the CGs also indicates the different propagation movements beneath the cirrus.

Thus, this was a conglomerate MCS with much internal sub-structure and no long-lasting leading edge convection, or consistent motion due to propagation. This event appears somewhat similar to what Blanchard (Bull. Amer. Meteor. Soc., 71, 994-1005) terms a "chaotic MCS," see for example his Fig. 6.

Fig 4 - IR image 12Z 27 Jul - This image shows a sunrise MCS that developed near midnight last night just ahead of a distinct 500 mb circulation moving southwestward within the larger- scale anticyclone that is over the Southwest. It is almost as impressive as the MCS on Tuesday night. This MCS, however, did exhibit leading convection/trailing stratiform through much of its life and has also propagated steadily toward the southwest. A pleasant morning surprise to find light rain falling and rain in the gauge again (0.17" is all). As the MCS came overhead, no thunder or lightning was observed at TUS - in marked contrast to the observations at David Monthan AFB, and also at our house.

Fig 5 - Catalinas photo at 1300Z 27 Jul - view of the Catalinas taken through light rain at about 6am this morning.

Yet another interesting day, thanks to the great moisture surge produced by Tropical Storm Emilia on Monday night.