Tuesday, July 10, 2007

Advanced Hurricane Forecasting

With the 2007 hurricane season under way, scientists believe their new forecasting model will make more-accurate predictions, thereby saving lives.

By Brittany Sauser

Forecasting destruction: An image of Hurricane Katrina nearing peak strength was taken on August 28, 2005, by NASA satellites (top). The new hurricane-forecasting model, HWRF, reproduced the life cycle of Hurricane Katrina and was able to more accurately predict its intensity (bottom image). Credit: NASA (top); NOAA/National Weather Service Environmental Modeling Center (bottom).

Multimedia •  View images of the GFDL and HWRF models.

To view other model analyses and forecasts you can visit the National Weather Service's National Center for Environmental Prediction, and this page from Penn State.

Forecasters are predicting yet another very active hurricane season for 2007, but this year meteorologists expect to be able to more accurately predict the path, structure, and intensity of storms. The device that will make this happen is a new hurricane-forecasting model developed by scientists at the National Oceanic and Atmospheric Administration (NOAA) Environmental Modeling Center. It will utilize advanced physics and data collected from environmental-observation equipment to outperform current models and provide scientists with real-time three-dimensional analysis of storm conditions.

The model is able to see the inner core of the hurricane, where the eye wall is located, better and in higher resolution than all other models, says T. N. Krishnamurti, a professor of meteorology at Florida State University. The eye wall is the region around the hurricane eye where the strongest winds and heaviest rains are located, thus the place of the highest storm intensity. "It is a very comprehensive model that is a significant development for hurricane forecasting," says Krishnamurti.

Currently, experts at the National Hurricane Center and the National Weather Service rely mostly on the Geophysical Fluid Dynamics Laboratory (GFDL) model. The model, which has been in use since 1995, forecasts the path and intensity of storms. Until now, it was the only global model that provided specific intensity forecasts of hurricanes. And while it is a very good model, it's limited by the amount of data it's based on. "It has a very crude representation of storms," says Naomi Surgi, the project leader for the new model and a scientist in the Environment Modeling Center. "GFDL is unable to use observations from satellites and aircraft in its analysis of the storm."

Isaac Ginis, a professor of oceanography at the University of Rhode Island (URI) who helped develop the GFDL model, agrees that the old model "has too many limitations" and, while it's able to forecast the path of a storm well, it is not as skillful at forecasting the intensity or power of a storm. Ginis is now a principal investigator for the new model, called the Hurricane Weather Research and Forecast (HWRF) model, which is able to gather a more varied and better set of observations and assimilate that data to produce a more accurate forecast.

This new model will use data collected from satellites, marine data buoys, and hurricane hunter aircraft, which fly directly into a hurricane's inner core and the surrounding atmosphere. The aircraft will be equipped with Doppler radars, which provide three-dimensional descriptions of the storm, most importantly observing the direction of hurricane winds. The aircraft will also be dropping ocean probes to better determine the location of the loop current, a warm ocean current in the Gulf of Mexico made up of little hot spots, known as warm core eddies, that give hurricanes moving over them a "real punch," says Surgi.