Profiling Radar and Snow Microphysical Properties from Extended Ground Observations in the Upper Great Lakes (192)

David Beachler, NOAA/NWS, Marquette, MI



This study presents results from a ground-based profiling radar and in-situ snow microphysicsobservational suite located at the Marquette, Michigan National Weather Service WeatherForecast Office in the Upper Great Lakes near the southern shore of Lake Superior. CombinedMicro Rain Radar (MRR) and Precipitation Imaging Package (PIP) observations are presentedfor numerous case studies to both illustrate the capabilities of these instruments and to documentunique radar and concomitant microphysical properties associated with different snowfall modesfrequently observed in this region.MRR and PIP observations for a multi-day snow event that locally produced over 90 cm ofaccumulated snow are presented to illustrate the distinct cloud macrophysical and snowmicrophysical properties associated with three different distinct phases of this snowfall event(synoptic, lake/orographic enhanced, and lake-effect phases). The MRR observations indicatedeep snow-producing cloud structures with a fall streak appearance during the synoptic (or&ldquosystem&rdquo) snow phase, followed by shallow vertically-oriented features embedded within thedeeper radar signatures during the lake/orographic enhancement stage. The lake-effect stage isdefined by relatively shallow (&amplt 1.5 km deep) convective MRR-observed cloud structures. Snowparticle size distributions (PSD) measured by the PIP indicate distinct PSD broadening andsystematically larger and less dense particles as the event undergoes the three daytransformation. Numerous other case studies documenting typical lake-effect, orographic, andrain-to- snow transitions are also presented to illustrate the varied cold-season precipitationevents at this particular site.The value of these ground-based observations for cloud microphysics parameterizationimprovements and spaceborne remote sensing applications are also presented, including the radarreflectivity to snowfall rate relationship dependence on snowfall mode and seasonal MRRanalyses that emphasizes the predominance of shallow snowfall events in the Upper Great Lakes.