Forecaster Nash

What the 1-2-3 Rule amounts to is that although the present position of a storm can be known with reasonable certainty (within 30 nautical miles in the case of Tropical Storm Ioke), the further into the future you attempt to forecast the storm's position, the less precise your forecast becomes. A mariner would like to know where the storm will be tomorrow and the day after that and so on. This is possible, but only at the cost of increasing uncertainty. So what's done is to plot the uncertainty.

The wise men of the sea have decided that winds over 34 knots and the upset water and waves that accompany such winds in the vicinity of a tropical revolving storm are risky and dangerous. So based on information in the latest TCM, we can plot the radii of 34-knot winds. These can be forecast for the announced position of the tropical storm or hurricane. But what will happen in 12 hours, one day, one and a half days, and two, three, four, and five days?

A professional forecaster decides what these winds will be and where they will be found, and we plot his results. This gives us a small circle at the beginning and a series of circles of increasing size as we move away from the first position. I've plotted four of the eight positions on the August 20 TCM for Hurricane Ioke and have made the accompanying drawing, which looks like a squashed balloon.

1-2-3 Rule plot of Tropical Storm Ioke south of the Hawaiian Islands on August 20, 2006. At 0900 UTC, the storm position is shown along with the predicted centers at 24, 48, and 72 hours. For 72 hours the wind prediction is 70 knots with gusts to 85. This 1-2-3 Rule plot warns mariners to stay outside the heavy black line where the predicted wind should be no more than 34 knots. This revolving storm is moving west-northwest at 11 knots.

1-2-3 Rule plot of Tropical Storm Ioke south of the Hawaiian Islands on August 20, 2006. At 0900 UTC, the storm position is shown along with the predicted centers at 24, 48, and 72 hours. For 72 hours the wind prediction is 70 knots with gusts to 85. This 1-2-3 Rule plot warns mariners to stay outside the heavy black line where the predicted wind should be no more than 34 knots. This revolving storm is moving west-northwest at 11 knots.

For 0 hours, the time of the forecast, we're told that 34-knot winds extend outward as much as 30 miles from the storm's center, and the uncertainty of the current position of that center is 30 miles. We therefore draw a circle with a radius of 60 miles around the storm's reported present position. (Note that the circle drawn for each forecast uses the highest value of the four wind quadrants. This makes the plotting simpler and provides additional safety.)

In 24 hours the storm is predicted to be centered at 11.7° N 163.3° W. At this location we draw a circle with a radius of 30 miles (present position uncertainty) plus 65 miles (maximum forecast 34-knot wind radius) plus 100 miles (average 24-hour track error), or 195 miles.

In 48 hours the storm is predicted to be at 13.9° N 168.1° W. We draw a second circle with a radius of 30 miles plus 120 miles (maximum extent of 34-knot winds in the 48-hour forecast) plus 200 miles (average two-day track error), or 350 miles. And around the predicted 72-hour location we draw a circle with a radius of 30 miles plus 150 miles plus 300 miles, or 480 miles. That's a circle almost 1,000 miles in diameter that we want to be outside of in three days.

The rule of thumb is that the average track error is 100 miles for the 24-hour forecast, 200 miles for the 48-hour forecast, and 300 miles for the 72-hour forecast.

But what, you ask, happens if I don't have the latest TCM bulletin from the weather people? Suppose the radio has broken down or the propagation is bad. Maybe I don't have the most recent frequencies and times of transmission. Or maybe the ship's batteries are dead. Then what?

Then you're on your own, and it's back to Buys Ballot's Law to find out what the cursed hurricane is doing. The law says that when you stand with your back to the wind in the Northern Hemisphere, the center of low pressure will be to your left. High pressure will be to your right. If you do this faithfully once an hour, and write down the bearings of the highs and lows and the barometer reading, in time you should be able to construct a little drawing of the hurricane's path. In general you will want to sail toward high pressure and away from low pressure.

If the pressure is falling, there's a noticeable swell, the wind stays in the same direction, and the cloud cover is thickening and lowering, you may be in the direct line of the hurricane.

"Bands of dark, heavy clouds alternate with thinner spirals as the wind increases," says weather expert William Crawford. The wind will drop to zero in the eye, and when it resumes, the wind will be from the opposite direction and the barometer will be rising.

If our intrepid sailor is in the right-hand semicircle as Tropical Storm Ioke is passing, the barometer will fall at first, then begin to rise. The wind will slowly veer from north to east to south. The passing eye will probably be out of sight roughly to the west of the boat.

If our little ship is in the left-hand semicircle as Ioke passes, the wind will back from north-northwest to west, then south-southwest. Remember that if we're in the Northern Hemisphere and the wind veers, our vessel must be in the right-hand semicircle. If the wind backs, we must be in the left-hand semicircle.71

But even if you have a TCM position report of the hurricane or have worked out your own from Buys Ballot's Law, it will take a steady hand to plot it on the chart while the boat is jumping around and the wind is screeching outside. The crew may be terrified, and some may be wiped out and in their bunks. There can be problems with sails or deck gear. Even if you are able to think clearly and work out a plan, it may be impossible to carry it out.

It seems ironic that once you're locked into really severe stuff, the weather reports themselves are of little use except to indicate a way out that you may be unable to take. This is why it's so important to avoid such tempests and begin immediate actions to increase your distance from a tropical revolving storm, no matter what direction you have to go.

If all else fails and things are looking dicey, I would quickly put out a Jordan Series drogue or any sort of drogue you might have on board. If you don't have any dedicated off-the-boat gear, tie a long stout line to an anchor and secure the inboard end of the line to the strongest point on the stern (or use a bridle). Fit some chafing gear; then toss the anchor astern, and retire below.

I would pad myself with a couple of pillows and scrunch down behind the lee cloth in my bunk with a good book on espionage. I would pretend that I was a spy and about to meet the luscious Natasha Vasilotova, who was desperate for my photos of the secret machinery. . . .

Can you go to windward in a hurricane? Here we see a boat trying hard in winds above 60 knots during the 1998 Sydney—Hobart race. The sea is all white and running at heights of perhaps 20 feet, the crew is down to a storm trysail, and it's quite apparent that the yacht is making abysmal progress. The racing crew is perched along the windward rail, but the boat is heeled over so far that the crew's combined weight (1,500pounds?) is having little effect. In fact, with the boat heeled so extremely to port, the railbirds' weight is actually increasing the capsizing force. Presumably this is only a momentary knockdown, but with the rudder out ofthe water, the boat cannot be steered, no matter how skilled the helmsman. With the storm trysail set, the mast looks to be under extreme pressure; once it gets out ofcolumn, the chances of failure are great. And when the mast goes, it's the end ofthe race and a whole new set ofhazards and dreadful expenses.

What would I have done? Since progress to windward is hopeless, I would have stopped the yacht or run off downwind. In a race, however, the aim is to stay on course no matter what the price. Nevertheless when sailing becomes a survival situation it's time to take other action. I would have stopped the boat, taken down the sail, and run off downwind under bare pole. This would have taken the pressure offthe mast, all the crew except one could have taken refuge in the cabin, and the boat would have slowly gone downwind. Ifthe yacht was moving too fast downwind, I would have dropped an anchor on a long line over the stern. At sea, survival is mostly a waiting game; in 12 (?) hours the wind might be down, it might change direction, and the sailing conditions might be more reasonable. I think it's smarter to finish late than not to finish at all. As for the race, the competitors may be faring even worse. Who knows? Sometimes at sea, everything's a crapshoot.

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