Abstract
Extensive reconnaissance of m ature Hurricane Isbell was made October 14,1964. Data collected at 850 mb,700 mb,550 mb,200 mb,150 mb, and in the lower stratosphere reveal that the storm had a warm core (up to 15°C above normal in the eye) from sea level up to 115 mb and a cold core between 115 mb and 90 mb. Convection in the storm was very intense and clouds rose into the stratosphere, with isolated clouds projecting 2.5 km above the tropopause. The lower stratosphere (up to 4000 ft above the tropopause) had temperatures ranging from 1.8°C to 7.6°C below normal. Even in the stratosphere, which had a very stable lapse rate, there were temperature gradients as large as 5°C per 10 n miles in the vicinity of the hurricane center.
The cyclon i c wind circulation decreased from a maximum of 116 kt at low levels to near zero at 115 mb, and increased, relatively, in the layer near the tropopause. Data were insufficient, however, to verify whether the very weak wind field measured at the tropopause and in the lower stratosphere was actually cyclonic.
The tropopause was abnormally high and cold above the hurricane with the height varying inversely with distance from the storm, at least beyond the vicinity of the eye wall. Data were insufficient to define the slope of the tropopause over the eye and eye wall.
