The National Hurricane Center issues analyses, forecasts, and warnings over large parts of the North Atlantic and Pacific Oceans, and in support of many nearby countries. Advances in observational capabilities, operational numerical weather prediction, and forecaster tools and support systems over the past 15-20 yr have enabled the center to make more accurate forecasts, extend forecast lead times, and provide new products and services. Important limitations, however, persist. This paper discusses the current workings and state of the nation's hurricane warning program, and highlights recent improvements and the enabling science and technology. It concludes with a look ahead at opportunities to address challenges.

With the multitude of cloud clusters over tropical oceans, it has been perplexing that so few develop into tropical cyclones. The authors postulate that a major obstacle has been the complexity of scale interactions, particularly those on the mesoscale, which have only recently been observable. While there are well-known climatological requirements, these are by no means sufficient.A major reason for this rarity is the essentially stochastic nature of the mesoscale interactions that precede and contribute to cyclone development. Observations exist for only a few forming cases. In these, the moist convection in the preformation environment is organized into mesoscale convective systems, each of which have associated mesoscale potential vortices in the midlevels. Interactions between these systems may lead to merger, growth to the surface, and development of both the nascent eye and inner rainbands of a tropical cyclone. The process is essentially stochastic, but the degree of stochasticity can be reduced by the continued interaction of the mesoscale systems or by environmental influences. For example a monsoon trough provides a region of reduced deformation radius, which substantially improves the efficiency of mesoscale vortex interactions and the amplitude of the merged vortices. Further, a strong monsoon trough provides a vertical wind shear that enables long-lived midlevel mesoscale vortices that are able to maintain, or even redevelop, the associated convective system.The authors develop this hypothesis by use of a detailed case study of the formation of Tropical Cyclone Oliver observed during TOGA COARE (1993). In this case, two dominant mesoscale vortices interacted with a monsoon trough to separately produce a nascent eye and a major rainband. The eye developed on the edge of the major convective system, and the associated atmospheric warming was provided almost entirely by moist processes in the upper atmosphere, and by a combination of latent heating and adiabatic subsidence in the lower and middle atmosphere. The importance of mesoscale interactions is illustrated further by brief reference to the development of two typhoons in the western North Pacific.

The 2008 Atlantic hurricane season is summarized and the year's tropical cyclones are described. Sixteen named storms formed in 2008. Of these, eight became hurricanes with five of them strengthening into major hurricanes (category 3 or higher on the Saffir-Simpson hurricane scale). There was also one tropical depression that did not attain tropical storm strength. These totals are above the long-term means of 11 named storms, 6 hurricanes, and 2 major hurricanes. The 2008 Atlantic basin tropical cyclones produced significant impacts from the Greater Antilles to the Turks and Caicos Islands as well as along portions of the U.S. Gulf Coast. Hurricanes Gustav, Ike, and Paloma hit Cuba, as did Tropical Storm Fay. Haiti was hit by Gustav and adversely affected by heavy rains from Fay, Ike, and Hanna. Paloma struck the Cayman Islands as a major hurricane, while Omar was a major hurricane when it passed near the northern Leeward Islands. Six consecutive cyclones hit the United States, including Hurricanes Dolly, Gustav, and Ike. The death toll from the Atlantic tropical cyclones is approximately 750.A verification of National Hurricane Center official forecasts during 2008 is also presented. Official track forecasts set records for accuracy at all lead times from 12 to 120 h, and forecast skill was also at record levels for all lead times. Official intensity forecast errors in 2008 were below the previous 5-yr mean errors and set records at 72-120 h.

The 2002 Atlantic hurricane season is summarized. Although the season's total of 12 named storms was above normal, many of these were weak and short-lived. Eight of the named cyclones made landfall in the United States, including Lili, the first hurricane to hit the United States in nearly 3 yr.

A summary of the 1996 Atlantic hurricane season is given, and the individual tropical storms and hurricanes are described. This was the second active year in a row with a large number of intense hurricanes. Hurricane Fran, which hit the coast of North Carolina, was the strongest system to make landfall, and also the most destructive.