Observations of Appalachian Fronts during Two NSF Educational Deployments

A portion of NSF funding is reserved for the deployment of observing facilities to universities with the primary goal of experiential learning, rather than answering specific scientific questions. However, the latter can still be addressed with the collected datasets. Two recent deployments to Millersville University in southeast Pennsylvania resulted in observations of multiple types of frontal interaction with the Appalachian Mountains.

In April 2016, a Doppler on Wheels (DOW) sampled ahead of two fronts during Millersville University Educational DOW (MEDOW). In the first event, the boundary was marked by a post-frontal region of minimal returns with a vertical structure at times resembling a gravity current. This is consistent with a WRF simulation where an elevated head of increased northerlies develops as the front crosses the mountains. The second front was the focus of lift for an MCS which built northward from a line of storms passing to the south of the Appalachians through Georgia. As it approached the DOW, bowing segments and small hail began to appear.

Student Experience in Airborne Research in the Mid-Atlantic Region (SEAR-MAR) was a deployment of the University of Wyoming King Air in November 2017. In contrast to the two MEDOW fronts, the SEAR-MAR cold front developed a prefrontal trough during the morning flight after the wind shift and temperature gradient were initially collocated upstream of the Appalachians. The trailing frontal boundary was flown through again in the afternoon with mountain wave activity beginning to occur. Another mountain wave field was sampled on a later date in a different post-frontal airmass and seemed to show propagation off two ridge lines oriented in different directions.

By combining these types of high-resolution field observations of the same type of weather system displaying different characteristics, future students can perform studies on what the key factors are in determining behavior.