David Wolfson
EF5
The Monsoon is a general term for a number of factors (some quite subtle) that combine in varying degrees during the summer season to produce convection. The various factors interact with the geography in different ways, though the mountains in general tend to initiate and focus the convection as you'd expect.
In my (non-professional) observation there are two basic categories: diurnal insolation-driven and disturbance-driven.
In the first, the convection responds mainly to sun heating. It will initiate over the "sky-islands" of Southern Arizona (Catalinas, Santa Ritas, Pinalenos, Huachucas, Chiricahuas, etc.) and on the Mogillon Rim ( http://en.wikipedia.org/wiki/Mogollon_Rim) around noon or a little after. It will then move off the mountains with the mid-level flow and cycle as multi-cell air-mass storms. As sunset approaches the storms tend to clarify and settle enabling those beautiful photo opportunities. Nighttime usually stables out surprisingly fast.
In the second, the multi-cells tend to coalesce into lines and into larger clusters with mesoscale and occasional synoptic scale disturbances. Last night in the Phoenix area was such a case, and you can still see the disturbance in the WV loop approaching Las Vegas this morning. Other than the occasional easterly waves the experts can see coming for a long time, these disturbances seem usually to be generated by the subtle upper thermodynamics of the "Four Corners High" mechanism that characterizes the monsoon flow. The disturbances seem to surprise everybody -- including the NWS. Watch for persistent linear storm formations perpendicular to and traveling with the flow for early warning. These tend to move smartly along, can occur at all times of the day (though nocturnal seems preferred), and are more classically chaseable.
Well, that's the general overview. Where are you traveling to, Cstok? Susan Strom I'm sure can give you some more particular tips on locations, etc.
In my (non-professional) observation there are two basic categories: diurnal insolation-driven and disturbance-driven.
In the first, the convection responds mainly to sun heating. It will initiate over the "sky-islands" of Southern Arizona (Catalinas, Santa Ritas, Pinalenos, Huachucas, Chiricahuas, etc.) and on the Mogillon Rim ( http://en.wikipedia.org/wiki/Mogollon_Rim) around noon or a little after. It will then move off the mountains with the mid-level flow and cycle as multi-cell air-mass storms. As sunset approaches the storms tend to clarify and settle enabling those beautiful photo opportunities. Nighttime usually stables out surprisingly fast.
In the second, the multi-cells tend to coalesce into lines and into larger clusters with mesoscale and occasional synoptic scale disturbances. Last night in the Phoenix area was such a case, and you can still see the disturbance in the WV loop approaching Las Vegas this morning. Other than the occasional easterly waves the experts can see coming for a long time, these disturbances seem usually to be generated by the subtle upper thermodynamics of the "Four Corners High" mechanism that characterizes the monsoon flow. The disturbances seem to surprise everybody -- including the NWS. Watch for persistent linear storm formations perpendicular to and traveling with the flow for early warning. These tend to move smartly along, can occur at all times of the day (though nocturnal seems preferred), and are more classically chaseable.
Well, that's the general overview. Where are you traveling to, Cstok? Susan Strom I'm sure can give you some more particular tips on locations, etc.
