An accurate description of the tropical cyclone surface wind field near and after landfall in real-time is important for warning, preparedness, and recovery efforts. The timing and size of the hurricane warning area is dependent on the time necessary to evacuate areas threatened by storm surge, the accuracy of the track forecast, and the magnitude and extent of the wind field. During a hurricane threat, an average of 550 km of coastline is placed under a hurricane warning, which costs about $200 million in preparation per event. Typically a hurricane will only affect about 25% of this area, hence overwarning is a costly and expected result of uncertainties in the forecast and observing system. Also of great cost and consequence is the potential for underwarning due to deficiencies in our ability to observe and forecast surface winds and intensity changes in hurricanes. "Hurricanes at Landfall" is an adaptive observing system strategy to reduce overwarning and mitigate damage through improved analyses and forecasts of the pattern, extent, and intensity of damaging winds associated with landfalling TCs .
A major source of difficulty in past efforts to predict hurricane intensity, wind fields and storm surge at landfall has been the inability to measure the surface wind field directly and the inability to predict how it changes in response to external and internal forcing.The surface wind field, defined as the radius of maximum winds and the radii of hurricane force, 50 kt, and gale force winds in each quadrant of the TC, must presently be estimated from a synthesis of scattered surface ship and/or buoy observations and aircraft measurements at 1.5 km to 3.0 km altitude. This task is complicated by variations with height of the stormsĀ structure, such as the change with height of storm-relative flow due to environmental wind shear and to the variable outward tilt of the wind maximum with height. To help overcome these difficulties, we propose an adaptive observing strategy comprised of a mix of conventional in-situ, air-deployed sensors, and air-, and space-borne remote sensors allowing the surface wind field to be directly measured. It has been generally agreed that changes in the wind field will be brought about by (1) changes in the large-scale environmental conditions, (2) changes in the underlying boundary, and (3) naturally-evolving internal dynamics.
Direct linkages between TC intensity change and observed air-sea changes have been difficult to make since many storms are also exposed to tropospheric environmental influences. In addition, detailed oceanographic and surrounding environmental observations in the atmosphere have been generally lacking from which to make comparisons. Thus, an additional goal of Hurricanes at Landfall is to examine the link between changes in intensity and enhanced air-sea interaction processes brought about by storm movement over major oceanic features