The clouds also draw air inward from outside the eye, thus concentrating the counter-clockwise rotation and increasing the swirling winds. In a hurricane, the strongest winds are near the surface and lie just outside the eyewall. Hurricanes' motion is largely governed by the winds that surround them. In effect, the storm is simply carried downstream by the average environmental wind. This is where research can pay big dividends.
Warnings are expensive, even though they are essential for protecting people and property.
In individual cases, the cost depends upon the amount of coastal development. If a major city, such as Miami or New Orleans, lies in the warning area, it escalates dramatically. This dramatic result recognizes that hurricane motion is controlled by the state of the surrounding atmosphere, so that forecasts based upon accurate and timely measurements of that state are themselves more accurate. In these experiments, the atmospheric state was measured by omega dropwindsondes that were deployed by the NOAA WP-3D research aircraft . Released from an altitude of 5 to 7 kilometers, the sondes measured pressure, wind, temperature, and humidity as they fell to the sea on parachutes.