It is as you approach the inner eyewall that the pressure gradients change rapidly and the wind speeds increase. Down near the surface the storm might have a pressure of one thousand millibars, while at six thousand meters the pressure would be down to half that, with a corresponding drop in wind velocity at any point from the center.
Over two pots of coffee and innumerable arguments we sketched out a route we could take to circle the storm and survive. We had to make use of the prevailing winds, our expertise in handling high speed wind sailing, and our knowledge of the structure of the storm.
We would try to get into position and enter on the eastern side, just inside the first major rainwall, about seventy kilometers from the eye at about the four o’clock position. We would use the updraft at that location to climb to two thousand meters and turn toward the eye before we got caught in the side draft that would take us out and back down. Using the winds surrounding the eyewall we would climb another thousand meters, and fall into the eyewall near the two o’clock spot. If our calculations were correct, and the plan worked, we would then accelerate, brush the top of the comma itself, which would give us enough momentum to spin into the eyewall. Once there we would climb the stack of upward flowing air and fight our way into the eye at about nine kilometers up. Once we were in the eye we would have a few moments of rest before fighting our way back out.
Our plan was to drift around in the eye to the eight o’clock position and dive near the surface, fight our way through the trailing eyewall—where the wind gradients were less—be carried back up to altitude by the up-wellings of the trailing rainwalls and be carried around to the starting four o’clock position. Naturally the storm would have moved by this time and the same relative position would be far northeast of where we had started. Hopefully, our path would describe a long ellipse with the eye of the storm as its primary center.
The “ifs” of the plan were manifold. It depended upon our hurricane following a decent track and not recurving on itself, bending back and destroying the smooth laminar wind flows on which we depended. It depended on the storm structure having a nicely rounded shape and not going excessively elliptical on us, which would throw us far off course and make retrieval, provided we survived, difficult if not impossible. It depended on the reliability of the NOAA weather model we had downloaded and our faith in accuracy of the wind and pressure dynamics described in a dozen or more meteorological texts. It depended on our gear being the best we could get. It depended on us using every bit of skill and knowledge we had acquired over the last five years of storm jumping. And, to be honest, it depended on the power of prayer and the will of God.
“Nine sixty millibars,” shouted the captain. At the same time the long ribbon unrolled from a standard at mid-deck. I watched it whip around for a few minutes before it steadied and hung straight out a few points off our stern. The captain was keeping us into the wind, showing us the shape of the wall we were penetrating. “Launch whenever you’re ready,” he said calmly. How could he be so damn laid back while fighting the seas, the winds, and his common sense to keep us on a true heading, I wondered. Is he as crazy as the rest of us? The answer was obvious.
“All right,” Jerry said with rising tension in his voice, “Let’s make sure of everything one last time before we go. Now just wait while I—”
“Wait, hell!” Mariah said, deployed her sail and kicked free of the clamps just as we reached the peak of a wave. I watched the wind rip the small pink parasail from her front pack, lift her clear of the deck, which disconnected her from our intercom link. I couldn’t see the thin strand of monofilaments from the reel that kept tension on her and ensured that she would rise against the wind. With a wind speed in excess of one hundred klicks even a small sail has enormous lifting power, equivalent to the large, low-speed parasails that they use to tow swimmers at all of the Caribbean resorts.
“God damn that woman,” Jerry muttered. “OK, here I go,” and then he launched when we hit the next peak. I watched the water wall build at the stern once again, feeling the boat drop away as we slipped down into the valley of anticipation. The heart monitor on the display showed my rate to be way up there, as if I had run a mile. Then the familiar elevator feeling came again as the boat started rising to the crest of the immense wave. With my heart hammering in my chest I waited for the crest to appear, one hand on each handle. There! The peak was coming. I released the clamps and the sail together, timing the emergence to match the peak of our climb.
WHAM! The sail opened with a snap as the straps pulled me forward while the reel line offered just enough resistance to force the tiny red kite above me to rise into the wind. I was yanked nearly horizontal as I instantly accelerated, smashing into the top of the departing wave and finding myself immersed in the gray water for a microsecond before emerging on the back side and begin climbing, water streaming out of my boots. The universe was a swirling buffeting mass of wind and water as my body turned this way and that, fighting the line from the reel and the straps pulling me aloft.
In less than a minute I had reached the end of the line and was flying nearly three hundred meters above the raging seas below. I could feel the snap of the automatic release going off, dropping the line from the reel and giving me to the fury of the storm. I was immediately accelerated to match the wind velocity by the fierce winds. I tried to twist around, to face away from the direction of travel, but the straps to the small sail stopped me. The altimeter showed me at a ground speed of just under one hundred kilometers per hour, just about even with the wind. I hit the release for the next chute and watched the wind whip the small red one and the sutliff away.
With an enormous kick of my feet I managed to turn partially around to face into the wind as my second chute tumbled and deployed. Now that we were moving relative to the wind the larger chute wouldn’t be ripped to shreds when it emerged, so went the theory. The instant it filled out to shape I began hauling on the forward and eyeward lines to dip that side and steer me toward the rear of the rainwall, where the rising winds were more likely to be found. My heads-up display showed me to be rising slightly, now at about 110 meters with a ground speed of less than one hundred. I checked the rate of climb a second later and saw that it had risen a few meters per minute, which indicated that I was following the plan so far. If I continued I would soon hit the major stream of warmer air and be able to start my ascent to the top of the storm.
The big difference between parachutes and gliders is that the chute merely slows the rate of descent while the glider uses aerodynamic properties to gain lift from the wind rushing over its surfaces. The chute above me used a minor fraction of the tremendous wind force to keep itself inflated and the rest to develop positive lift. I was, in effect flying into the wind even as Janice carried me backwards to her heart.
The outer annular ring of a hurricane, our first rainwall, is a twisting torus of wind that acts just like the roller-beater on a vacuum cleaner; sucking some of the warm air beneath it into a rising stream while feeding most of it inward to the central vortex; the eyewall. Close to the center of this wall of winds there is considerable turbulence as the rapidly rising winds, which are also moving horizontally around the torus and thus describe a spiral, mix into the smoother flow of the inner winds. The trick I had to master was to keep myself away from this turbulence and stay within the rising air streams. Either the pressure gauge or ground speed indicator would tell me which direction I was heading: Inward was lower pressure and outward was higher; inward was higher speeds and outer was lower. It was a delicate balance, but one we had all experienced before. I expected no problems on this phase of the jump.