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.

[1] Numerical model experiments are conducted to address the previously unexplained anomalously high storm surge along the Florida coast of Apalachee Bay during Hurricane Dennis (2005). The 2 -3 m surge observed during this storm cannot be obviously explained by the relatively weak local winds over this bay 275 km east of the storm center. Realistic and idealized numerical experiments demonstrate that the along-shore winds to the east of the storm center built a high sea level anomaly along the coast which traveled northward to Apalachee Bay as a topographic Rossby wave. The wave was amplified as the storm moved nearly parallel to the shelf and at comparable speed to the wave phase speed. These results suggest that enlarging the domain of the storm surge forecasting models can improve the surge forecast for a storm moving along a similar track, and have now been applied to operational use.

From October 1977 through November 1980 a current‐meter mooring was maintained in the Yucatan Strait. The meter was moored halfway between Mexico and Cuba, 145 m above the sill or in 1895 m of water. Motions of low frequency (<14−1 cycles/day) are oriented approximately parallel to the isobaths, 021°–030° true. Net drift for 3 years is to the SSW at an average velocity of 1.8 cm/s. Sustained southward flows at intervals of 8 months, which persisted for several months each, have average velocities of 5 cm/s, with randomly spaced bursts as high as 15 cm/s. Energy in subtidal frequency bands has significant peaks near 38−1 and 19−1 cycles/day, with a broad band of energy between 300−1 and 200−1 cycles/day. The latter peak is consistent with the approximately 8‐month interval between the southward flow events. Comparison with weekly areal coverage of the Gulf Loop Current from Geostationary Operational Environmental Satellite infrared observations shows little covariation, except that 8 months is typical of some anticyclonic eddy generation. There is little coherence of sill depth velocities with Naples sea level at subtidal frequencies, but with Miami there is coherence at several frequencies, notably 38−1 and 19−1 cycles/day. In the higher frequencies, the principal tidal motions are diurnal and are oriented somewhat across the isobaths toward the northwest, 346°–349° true, with counterrotating O1 and K1 constituents. No semidiurnal, inertial, or fortnightly energy is observed above the background continuum.

The infrared capabilities of the Geostationary Operational Environmental Satellite (Goes) are analyzed to obtain multiyear time histories of Gulf Stream meanders. Radiative transfer calculations using monthly mean profiles of atmospheric temperature and moisture are shown to overestimate cloud‐free equivalent soundings by 2–5 K. A simple relation is derived between temperature at the satellite, sea surface temperature, and transmissivity of the atmosphere at 11.6 μm, which allows an observer to determine if a known sea surface temperature gradient is observable from Goes knowing only the precipitable water content along the slant path to the spacecraft. More than 2 years of Goes observations of Gulf Stream meanders are analyzed as a randomly spaced time series using least squares spectral analysis; the dominant periods in the spectra, based on 1976–1978 data, are 250,65, and 10 days in the Gulf of Mexico; 30 and 6 days off Onslow Bay, North Carolina; and 45 and 5 days off New England. A summary of the meanders between the Yucatan Strait and the Grand Banks shows that the largest latitudinal variability is associated with the Gulf Loop Current. Comparison of meander periods with least squares spectra of historical Florida Current transports suggests that meanders in the Gulf of Mexico are related to variability with 4‐ to 16‐day and 40‐ to 100‐day periods in the flow.

Sea-surface temperature data obtained from satellite and subsurface temperature data obtained from ships are used to determine the intrusion of the The Loop Current extended considerably farther to the north during the last three winters than has been observed previously.