14.5 Small Scale Post-frontal Convection During OLYMPEX: A Start at Case Studies

Thursday, 26 January 2017: 2:30 PM
Conference Center: Tahoma 3 (Washington State Convention Center )
Ed Zipser, Univ. of Utah, Salt Lake City, UT

One of the important reasons for the ground validation campaigns conducted for both the TRMM
and GPM satellite missions is the need to understand the sub-pixel (5 X 5 km) variability of precipitation.
This variability is important even for large convective storms in the tropics, where individual updrafts
and downdrafts only rarely are uniform over 5 X 5 km.  For post-frontal convection in the Pacific Northwest
of the United States, it could be especially important, in view of the shallow nature of this convection and the
small horizontal dimensions of these showers.  In spite of their small size, it seems likely that as these showers
come onshore, that they may be responsible for a significant fraction of the snowpack in the Olympics, because
they often have been observed to deepen and grow upscale.  It will be of great interest to use surface-based
and airborne radar data to quantify the dimensions of these showers both offshore and as they ascend the
slopes of the Olympics. This talk reviews some of the radar and aircraft data for some of the best-observed
cases during OLYMPEX, on 10 and 13 December, when heavy precipitation behind occluded fronts was
sampled by the project and WSR-88D radars, and 3 well-coordinated aircraft missions.
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