A MULTISCALE ANALYSIS OF A CASE OF SLOW GROWTH RAPID CYCLOGENESIS DURING CASP-II

The cyclogenesis of 27 February through 6 March 1992 represents a nove l case of rapid intensification and slow growth with substantive plane tary-scale signatures. Its evolution, predominately continental, has b een documented with the aid of conventional station and grid-point dat a. Its novel slow growth, yet rapid intensification, is associated wit h its interaction with two distinct potential vorticity (PV) maxima of differing origins: One travelling from the North Pacific and one asso ciated with an amplifying system in Hudson Bay. The large-scale dynami c and thermodynamic structures are documented throughout its life cycl e. Associated with the cyclone's slow-growth process is strong pre-exi sting surface frontogenetic forcing and strong upper-level ascent forc ing throughout the cyclone's unusually long period (48 h) of anteceden t spinup prior to the onset of explosive intensification. Its mesoscal e structure, documented with the aid of three-hourly soundings, two-mi nute mesonet data and research aircraft measurements, reveals the pres ence of a pinched-off warm pool of air that wraps around the system. A dditionally, we find a substantive modulation of frontal structure ups tream of this warm pool, as the system propagates through eastern Newf oundland during its period of most rapid intensification.