Rationale—Tier 1

The principal rationale for a dense network of soundings, profilers and

radars in Tier 1, together with rain gauges, is to describe and understand

the diurnal cycle of precipitation and the structure of precipitation in the

core region of the NAMS and to better understand regimes associated

with intra-seasonal variability, including the influences of surges, jets,

surface fluxes and topographic blocking. These observations are

critical for budget studies and model validation.