The Influence of the Great Lakes on Northwest Snowfall in the Southern Appalachians

The Influence of the Great Lakes on Northwest Snowfall in the Southern Appalachians

Many meteorologists have had a great deal of difficulty predicting the weather in the southern Appalachians during winter weather events. One of the most common snowfall producers occur with a northwest wind bringing cold, moist flow at low levels. In combination with local instability the mountains act to force this flow upward producing increased vertical motions, which results in heavier snowfall. When this occurs it is known as a Northwest snowfall event. The focus of the study is to determine if the Great Lakes, in particular Lakes Michigan and Lake Superior, have an influence on the intensity of these events. Do these lakes add noticeable moisture to the air, and/or provide additional instability that would, in return lead, to more intense snowfall rates down the line? This project is a follow up to a study by Blair Holloway and Dr. Gary Lackmann at North Carolina State University. The WRF model is used to simulate a case study of northwest flow on February 10th, 11th 2005. The study will examine the impacts of different Planetary Boundary Layer (PBL) Schemes that influence moisture advection at low levels. In addition to looking at different PBL schemes, the study will examine the impact of shutting off fluxes of heat and moisture occurring over the Great Lakes. Differences in accumulated precipitation from the three simulations will be examined to determine their impact on the intensity of the northwest flow event in the Southern Appalachians.