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21 no clouds, Le., convection was not present to help drive the solenoid. The cloud tops usually 100ver below 500 mb during the unstable stage, but the clouds are still within the baroclinic zone as seen by the continuing cold air advection present within the cloud layer. The second and often the highest precipitation rate occurs during the early part of the unstable stage. If the storm is associated with a well defined upper level baroclinic zone, then the 500 mb temperature will typically decrease below the -23C cutoff temperature and the seeding generators will be turned off. If the blocking flo~v exists past the time the 500 mb temperature decreased below -23C, i.e., before the well defined convergence zone formed over Pagosa, then carryover seeding ~vill occur when the convergence zone forms. d. Dissipation stage During this stage the baroclinic zone has passed over the San Juans and the upper level flow is often north of west which produces downslope flow over Wolf Creek Pass. The pressure gradient and/or base of the subsidence inversion lo~vers to mountain top height. For one or both of the above reasons the airflow slo~vly ceases to move over Wolf Creek Pass, the precipitation from the scattered to broken cumulus clouds slowly ceases and the clouds dissipate, thus ending the storm. 2. An atypical but very organized storm The exception to the above typical storm structure and sequence occurred I I I I I I I I I I I I I I on 22 'Harch 1975. On this 'day a well organized storm approached the San Juans. I The center of the strong baroclinic zone passed directly across the San Juans. The storm was undergoing cyclogenesis throughout its passage across the south- Hestern staLes. This ~vas the only storm studied \vhich contained a frontal zone which passed over the area and displayed the normal sequences of weather phenomenon one observes over the midwest. Hith the frontal passage the I I I .