The three-nest structure of the GFDL Hurricane Model can be seen in this animation of vertically integrated relative humidity at half hour intervals between the model dates August 27-30, 2005. The magenta glyphs depict actual observed track positions.

Shown here is a model forecast of relative humidity, which can be compared to the actual satellite loop shown below.

Morris Bender

Timorthy Marchok

This animation illustrates a three-dimensional view of Hurricane Isabel approaching the East Coast of the United States. Results were obtained from a 99-hour forecast made at 8:00am, September 15th using the dynamical Hurricane Prediction System developed at NOAA's Geophysical Fluid Dynamic Laboratory (GFDL). Hurricane Isabel, which struck the Outer Banks of North Carolina on September 19th, 2003, caused extensive damage over a large area of the mid-Atlantic coast stretching from North Carolina to northern Virginia.

The animation displays the 350K isosurface (light-colored sheet) of "equivalent potential temperature", which measures the combined effects of heat and moisture and is therefore a fundamental quantity of hurricanes, a heat engine-like phenomena dependent on warm, moist tropical oceans and cumulus heating. The white arrows indicate wind speed and direction near the earth's surface.

As the hurricane's strong winds move across the ocean the cooler waters from below are brought up to the surface resulting in significant decrease in the sea surface temperature. Since the 2000 hurricane season this effect has been included in the operational GFDL model, by coupling the atmospheric model to the Princeton Ocean Model. This effect can clearly be seen in the animation, with a wake of cooler waters trailing the storm, indicated by the blue colors. Inclusion of the ocean coupling is important for the hurricane model to properly forecast the storm's intensity.

Since 1995, the GFDL model has provided forecast guidance of track and intensity for forecasters at the National Hurricane Center. In 2003, the model's vertical resolution and physics was significantly upgraded and the forecast guidance has been extended out to 5 days. So far this season, the improved GFDL model has out-preformed all other computer guidance.

Three-dimensional view of Hurricane Floyd as it approached landfall at Cape Fear on September 16, 1999. Results were obtained from a forecast made using the dynamical Hurricane Prediction System developed at NOAA's Geophysical Fluid Dynamic Laboratory (GFDL) and adopted as the official operational hurricane prediction model at the National Centers for Environmental Prediction (formerly the National Meteorological Center) starting with the 1995 hurricane season. The model correctly forecast the path of Floyd up the East Coast of the United States.

In the figure, winds in excess of gale force are indicated by the magenta and white arrows at the surface and top of the storm, respectively. The color shading at the earth's surface represents the precipitation, with red indicating higher intensities. The gray three-dimensional “cloud-like” feature is the 80% relative humidity surface, cut away on its eastern side to reveal the hurricane's interior structure, including the tube-like eye down the center. The horizontal plane slicing through the middle of the storm, and the red vertical arrows, indicate the upward motion in the storm's interior. Note the north-south asymmetry of the storm, as Floyd gets swept up in the larger-scale southwesterly flow.

Deadliest hurricane to hit Central America in 200 years. A category 5 storm at one point, Mitch stalled off the coast of Honduras, then slowly moved through Central America, causing massive flooding.

Shown in this diagram are wind vectors (near surface winds). Grey shading indicates particular contour of Equivalent Potential Temperature that highlights the surface inflow layer and eyewall region.