The analysis is focused on observations collected by instruments on the NRL P3. In particular, the ELDORA airborne Doppler radar provides reflectivity and pseudo dual-Doppler-derived winds. Also, the LEANDRE II differential absorption lidar allows for the derivation of water vapor mixing ratios. Additional data used in the analysis includes in situ temperature, mixing ratio, and wind from sensors on the NRL-P3 and University of Wyoming King Air, and vertical profiles of these parameters from dropsondes released by the Flight International Lear Jet and upsondes released by NCAR and NSSL ground-based sounding systems.
Pseudo dual-Doppler winds showed that the horizontal wind shear across the cold front increased with the approach of the diffuse boundary from the southeast. Organized patterns of misocyclones, indicated by vertical vorticity maxima (> 2 x 10-3 s-1) developed along the leading edge of the cold front. Vertical velocity maxima were observed at locations adjacent to the misocyclones. Two hours prior to convection initiation, the mean updrafts extended to 3 km MSL. As a consequence of increasing magnitudes of updrafts and vertical vorticity, areas of enhanced radar reflectivity and kinks in the reflectivity field became evident as the kinematic structure of the cold front evolved. In addition, water vapor mixing ratios increased in the layer between 2-3 km MSL during this period, thus making thermodynamic conditions more favorable for convection initiation.