The Meteorological and Oceanographic
forecasting factors in the Mid-Atlantic States
and their effects as they relate to
sea shore and inland forest geography


The traditional Mid-Atlantic States comprise the most densely-populated of the nine U.S. regions, and anchor the megalopolis which runs from Boston to Washington, D.C.. However, many people consider the Mid-Atlantic to be the states south of the Northeast, centered in Delaware, Maryland, and Virginia . The cities included New York City on the Hudson River, Philadelphia on the Delaware River, and Baltimore on the Chesapeake Bay. Diverse and complex natural processes continually change coasts physically, chemically, and biologically, at scales that range from microscopic (grains of sand) to global (changes in sea level). Human activity adds yet another dimension to coastal change by modifying and disturbing, both directly and indirectly, the coastal environments and the natural processes of change. Storms cause deep erosion in one area and leave thick over wash deposits in another. Plants retain sediment in wetlands and impede movement of coastal dunes. Natural processes that change the water level also affect coastal dynamics. The inland forest has a huge impact on winds and rain runoff into drainage basins.

The prevailing winds in the forests and along the coast produce winds at oblique angles. Even the slightest angle between the land and the waves will create currents that transport sediment along the shore. Tides help determine where the waves break, therefore, where sand is deposited and removed. Rip tides occur along most beaches and can move significant amounts of sand offshore. Storm systems along coasts contain high winds, create large waves, and cause storm surges that raise water levels as much as 7 meters above normal, carry sand seaward, forming offshore bars; much of this sand migrates landward during calm weather. The Mid-Atlantic seaboard, for example, hurricanes occur in the late summer and early fall, and storms are especially frequent during the winter months. Winter "eroding" beach and the summer "building" beach that is most common along parts of the west coast.

Predominantly closed bodies of water such as lakes in the inland forest areas experience dramatic water-level changes in response to precipitation, spring snowmelt, evaporation and human clearing of forest and the changing of slopes around it. The change in rivers that feed into the lakes also changes the available moisture available from summer time storms as they develop over lakes. Prolonged periods of wet weather or dry weather will a dramatic effect on precipitation forecasts for the Mid-Atlantic States in the future with the continued development and urbanization of the coastal and inland forest areas. Other local changes in water level occur when the land either rises or falls relative to the water table with draining of lakes faster than the water is replenished naturally.

During the last ice age, 26,000 years ago, vast quantities of sea water was changed into glaciers, resulting in a sizeable drop in the sea level. As we emerge from ice age levels, and sea level has been rising slowly by millimeters continuously; during the past century. These will eventually change the forecast parameters for the effects on precipitable water available for precipitation events and the net affect will be that the mountainous areas which normally held and slow progress of systems will begin to have less effect as and the coastal areas become thinner and the difference in the coast to mountain regions will narrow. The affect will cause systems to dump more water in a smaller area and increase the flooding potential in areas not normally affected by heavy rain events.

The slope of a coast is critical to determining how water-level changes will be affected and how the vegetation will stay, not withstanding the clearing of foliage for development. As the foliage is cleared and manmade structures are erected, will the moisture content available change to a more salt based? If the Mid-Atlantic States continue to clear trees and change the slopes of near shore communities, that will change the drainage basins of many areas. With that forecasting floods will become increasing more difficult. The long standing rule of forecasting thunderstorms and severe thunderstorms will change, but more important is the effects on those areas that have lost vegetation and the runoff of water from these storms. Rooted plants flourish along the shores of bays, estuaries, deltas, and other coastal environments that are protected from the full fury of pounding waves. Plants stabilize dunes through root networks. They build and maintain marshes by catching and retaining in their roots the fine sediment carried by the water. Their natural decay cycle further enriches coastal soils and sediment with decomposing plant matter. Differences in meteorological and oeanographical effects determine which foliage and sea plants will thrive in an environment. They are some plants that require total submergence, some require submergence and aeration, and others flourish except at the highest tides.

Gradual changes in weather patterns caused by the geography of the area, salinity and sea level allow normal plant succession to occur in protected coastal environments. Abrupt changes in these conditions often result in widespread destruction of plant communities and the loss of sediment being held by their roots. The erosion of barrier islands can lead to saltwater intrusion and increased wave action, which kills plants and destroys the wetlands behind the islands. With this destruction, forecasting the interaction with storm systems and the ocean will become much more difficult.

Human activities add another layer of complexity to the natural processes of coastal and inland forests. These will affect sources of new sediment to the coast and the movement of sediment within the coastal environment; they may promote changes in sea level. To prevent beach loss, groins are often constructed out into the water. These solid structures impede the littoral drift of sand caused by long shore currents. Seawalls constructed confine the wave energy and intensify the erosion by concentrating the sediment transport processes in an increasingly narrow zone. As the beach disappears, it is exposed to the full force of the waves. A seawall built to protect manmade structures along a coast will result in the complete disappearance of the beach itself. Off-road vehicles and foot traffic on sand dunes compact sand, destroying plant roots and animal burrows.

Coasts, as boundaries between land and water, are characterized by the geologic nature of the land, which is unstable and often fragile, and the dynamic power of wind and sea.

Some points to consider, Coastal erosion at widely varying rates, half of our valuable wetlands have been lost, Pollution of coastal areas has permanently contaminated ground water in some communities, hard-mineral resources such as sand and gravel for construction and beach nourishment are no longer available onshore. An expanding trend of growth and expanded development continue, and if sea-level rise brought on by potential climate changes also occurs, stress on our coastal environments will increase. The stewardship of our coastal resources requires balancing human needs and expectations with coastal realities. The forecasting of precipitation events will have to change based upon many factors, and the factors influencing their development is critical in any attempt to lessen the conflicts within computer models and empirical rules we use now and the natural processes that nature currently uses.

Ignorance and continued disregard of the geologic processes that constantly reshape our coasts are tragically intensifying the collisions between people and nature. A clear understanding of how coastal environments have formed and what natural changes they have undergone in the recent geologic past can be critical in predicting with confidence how we can forecast events in the future.

The Mid-Atlantic region, with its extensive coastline, is likely to suffer from the impacts of increased flooding and sea-level rise expected under scenarios of climate change. Changes in temperature and rainfall could take a toll on the regions important deciduous forests and migratory bird habitats and contribute to summer heat stress and other health risks. The coastal areas and inland forests are vulnerable to various climate changes; higher average temperatures, higher and lower precipitation levels, more intense rainfall and flooding.

Recommended actions for protecting against future impacts from sea-level rise and increased flooding include improving watershed management and reduced development in areas vulnerable to erosion and flooding.

Although overall forest productivity might increase, a relatively rapid shift in dominant forest types might foster invasive species and reduce diversity. Younger tree stands could also mean a decline in the role of forests in preventing erosion and siltation.

The heavily populated Mid-Atlantic region already suffers relatively more heat-related mortality than other parts of the country. How accurate will the heat stress forecast be with increased warming? Will there be an increase risk especially for children, the elderly and people lacking access to air conditioning, safe water supplies. Higher rainfall and floods increase the risks of waterborne diseases like Cryptosporidiosis. There are many concerns for the preserving of existing forests, wetlands, and coastal areas, and of cutting the volume of pollutants that flow into the region watersheds and coastal areas from agricultural production and human settlements and the effects on weather forecasts now and in the future.


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