5j.14 Observations of the 24 June 2003 Bow Echo Case during Bamex

In the late 1970s the convective system that is referred to as the bow echo was identified by Fujita (1978). It was identified as a type of convective storm structure associated with intense damaging winds or downburst (Johns 1993). As more of these systems were studied, a better understanding was made on their kinematic structure and dynamical processes. Bow echoes can range in size from 15 km to 150 km, and can occur at anytime of year (Klimowski et al. 2000). Much of the damage reported in the United Sates from non-tornadic winds is a result of bow echo systems. The “model” bow echo evolves from a single or large group of strong convective cells, to a bow-shaped line segment, and finally, to a comma-shaped echo in its declining phase (Fujita, 1978). The development of a bow echo can be related to a number of different synoptic variables and conditions. Strong bow echoes that produce widespread damage can occur in strong migrating low pressure systems as well as in rather benign synoptic patterns. During the Bow Echo and MCV Experiment (BAMEX) the ground-based platforms – the Mobile Integrated Profiling System (MIPS) and two NCAR MGLASS units – were deployed in advance of evolving mesoscale convective systems to monitor the environmental and storm properties of bow echo systems. On 24 June 2003 the MIPS was deployed at a site just south of Fort Dodge in Northwest Iowa, about 86 km from the Des Moines (DMX) WSR-88D radar. The NCAR MGLASS1 was deployed 76km to the west, and MGLASS2 was 176 km to the north. Around 0650 UTC, the MIPS acquired an excellent data set on a surging Figure 2.1.1 Skew-T sounding plot from the MGLASS 1 location at 0450 UTC on 24 June. This sounding was release 76 km from the MIPS location. The CAPE value was 2421 J kg-1, with a surface lifted index 0f -10.1, indicating an unstable air mass at this time. bow echo near the time of maximum radial velocity (exceeding 30 m s) measured from the DMX WSR88D The peak updraft within deep convection, ~20 m s , occurred about 10 minutes after the gust front arrival. The maximum surface wind gust of 24 m s was measured about 10 minutes after the gust front arrival, well behind the leading edge within relatively heavy precipitation. The goals of this paper are (1) to analyze MIPS data to define the environment preceding the bow echo (GLASS soundings and the radiometer (MPR)), and to describe the environment in the wake of the bow echo; and (2) to describe the internal storm structure from an analyses of MIPS 915 MHz profiler and electric field mill measurements, MPR measurements, ceilometer measurements, supplemented with Doppler analyses from the DMX WSR-88D and the NCAR Eldora airborne Doppler radar.