Tuesday, 24 January 2017
4E (Washington State Convention Center )
Five years of rainfall observations recorded from a set of rain gauges in the southern Appalachian Mountains (1036 – 2033 m ASL) were used to define a collection of heavy rainfall events, with the goal of providing context of the presence of atmospheric rivers in the eastern U.S. The events were categorized in to extreme and significant events by the amount of precipitation that was recorded by the rain gauges. GFS model analysis and GOES Sounder satellite fields were examined to find systematic differences between the two categories, as well as patterns in the synoptic scale flow. Integrated vapor transport (GFS analyses), GOES Sounder total precipitable water, and blended integrated water vapor fields were also analyzed to view the presence and extent of any atmospheric rivers present. The model analysis showed a persistent slow-moving high amplitude trough located upstream of the southern Appalachian mountains and an associated low-level jet directed from the Gulf of Mexico or Atlantic Ocean towards the mountain. Along with increased low level flow, an increase in precipitable water values was present throughout the southern Appalachian mountains, with amounts in the 90th percentile of normal for the time of year the various events took place. This research will aid forecasters and researchers better identify and predict atmospheric rivers in anticipation of high rainfall events. With this knowledge, situational awareness will be improved, and lead times increased with faster detection of high rainfall patterns.
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