OPAL: Minimum sea-level pressure in Opal as it intensified during its approach to landfall. Intensity forecasts are important because the major hurricanes almost always reach extreme intensity not through continued slow strengthening but through a process called "rapid deepening" that completely transforms the storm in a day or two. The difficulties that rapid deepening poses for forecasters are twofold: the hurricane becomes devastatingly intense, and events can outrun forecasts. A scenario for disaster - that nearly became a reality in Hurricane Opal of 1995 - is a category 2 hurricane that strengthens to a category 5 overnight. In the morning the storm strikes a populated coastline where the residents had prepared for the weaker hurricane they saw on television before they went to bed. The worst-case scenario was not realized in this instance because Opal weakened just offshore.