We present preliminary findings on the diurnal cycle of rainfall and the variability observed in regimes of convection. We also quantify the diurnal sea/land breeze circulations and other environmental flow characteristics. Our approach follows the reduced-dimension analysis methods of Carbone et al (1998, 2002). We examine the onset and movement of convection both parallel and perpendicular to the SMO and the GoC coastline, assuming that thermal forcing strongly influences the observed rainfall patterns. We observe at least two regimes:
The "undisturbed" regime: mainly produces rainfall in the region between the upper SMO and the mid-GoC; is heavily influenced by the elevated heat source and breeze circulations; and exhibits relatively little propagation of organized convection parallel to the mountains and the coast. The "disturbed" regime(s) is (are) often associated with longer-lived precipitation episodes and/or northwestward propagation nearly parallel to the coast. At least some of these events are associated with one or more of the following: so-called Gulf "surges" of southerly momentum; the passage of easterly waves; and the movement of tropical cyclones, which are often located to the south of our domain.
Between the writing of this abstract and the Conference presentation, we will further stratify the diurnal cycle data and quantify the lifecycle of events for both regimes. The statistics should help to define controlling factors in the regional climatology of rainfall and lead to improvements in the represeentation of convection for regional climate and NWP models.