Colloquium: February 26, 2008, 3:00 pm, EN6085A

Surface and upper-air data, collected as part of the Cumulus Photogrammetric, In situ and Doppler Observations (CuPIDO) experiment during the 2006 monsoon season around the Santa Catalina Mountains in southeast Arizona, are used to study the diurnal variation of the mountain-scale surface convergence and its thermal forcing. The environment is characterized by weak winds, a deep convectively mixed boundary layer, and sufficient low-level moisture for orographic cumulus convection on most days. The mountain is ~30 km in diameter, ~2 km high, and relatively isolated.   In response to a developing horizontal pressure gradient force towards the mountain, anabatic, convergent flow develops ~2 hours after sunrise and peaks slightly before local solar noon. The convergence strength is proportional to the daytime surface sensible heat flux. The interplay between surface convergence and orographic thunderstorms is examined. The impact of convection on surface convergence is more apparent than the impact of surface convergence on convection.