December 21, 2001
CYCLONE CISSIES

After five months cruising the Southwest Pacific, it is time for us to head out of the Tropics and out of the cyclone belt. The cyclone season officially began on November 1 and we left New Caledonia for Australia on November 14th, already two weeks into the season.

The occurrence of cyclones has a normal distribution, however, so the first and last month (April) have fewest cyclones. January, February and March are the peak months with an average of 2 to 3 cyclones per month. The average for the whole season is 8 to 10, around the same number as the Caribbean gets.

To Stay or Go?

Not everyone leaves for the cyclone season. As we planned our departure there were a number of crews deriding the exodus of yachts. In explaining their decision to stay the most typical claims included:

"They haven't had a cyclone in xx years" (where xx is a random number)
"We keep an eye on the weather and we can move out of the way if we have to."
"There are plenty of hurricane holes if you know where to go."
"Chances are very slim of one passing over where you happen to be."

Everyone must make their own decisions about these matters: Freedom is one of the joys of yachting.

Aboard THETA VOLANTIS we never have the debate. We are committed leavers. We stretch the boundaries a bit, leave a little late or move back in early, but always with a watchful eye on the weather. And that is one of the reasons we leave. We simply do not want to spend 6 months watching the weather that carefully, having false alarms and periods of anxiety waiting to see if something will develop or fizzle out.

Sadly we also know several people who have lost their boats (or suffered major damage) in hurricanes, which undoubtedly colors our views. In all cases, the hurricane was forecast and people either left it too late to escape (or were too afraid of getting caught at sea) or because they thought they were in a safe hurricane hole.

One common mistake is to forget about the actions of other boats. A hurricane hole to yourself is one thing--as soon as another boat uses it you have lost control of the situation. In 1995 one of the recognized safest hurricane holes in the Caribbean was the scene of massive destruction because one large (uninsured) yacht broke free.

So we like to sleep easy and we get a change of environment by leaving the Tropics for the season.

Where to Stay

If you do decide to stay there is the choice of where to stay. In very low latitudes (less than about 10 degrees) you are safer because cyclones cannot develop close to the equator, as the Coriolis force is not sufficient to create the spinning effect that cyclones need.

In the Southwest Pacific, island groups such as Tuvalu (5 to 9 degrees south) are just on the edge of the cyclone belt and if one develops nearby you can move further toward the equator, which lessens the chance even further that you will be affected. (Tuvalu was hit by cyclones twice during the El Nino 1997/8). Of course during the summer months these low latitude areas are very hot and humid, which is one reason we prefer to head to a temperate country like New Zealand or, this year, Australia. Further south, favorite areas for the cyclone season such as Fiji, Tonga and Vanuatu are much more vulnerable. For example Fiji is hit by a dozen cyclones a decade.

Another consideration if you decide to stay in these higher latitude areas is where do you run to if a cyclone heads your way. In the Southern Hemisphere cyclones travel west southwest, curving around anticlockwise. That means that making a run for Australia is out of the question, as it is in the track of the cyclone. When the cyclone curves, it brings New Zealand into its sights.

Although as they move out of the Tropics (south of 23.5 degrees south) they cease to be cyclones, they do not disappear. They simply become powerful and dangerous subtropical storms. They increase in size dramatically, covering a much larger area than an average cyclone. So, again, the escape path to New Zealand or Australia may be cut off.

Heading north should put you in the evasion and/or navigable circle (remember, "navigable" is a relative term), but reluctance to go to sea when a cyclone is developing deters many from taking this action. Islands to the north such as Samoa do not have as many safe anchorages as Fiji or Tonga so it is easy to persuade yourself to stay.

Be aware too that although a cyclone may pass a considerable distance from you, the swell will be felt hundreds of miles away. Swell can make anchorages untenable and puts considerable strain on anchoring hardware.

Where is Safe?

For the Southwest Pacific area, New Zealand and Australia are the obvious choices, though the Tropic of Capricorn crosses Queensland (in Australia) about one-third of the way up, making the northern part tropical and placing it in the cyclone belt (called monsoons in this area.)

Brisbane and Mooloolaba, both popular areas for cruising yachts sitting out the cyclone season, are below the cyclone belt.

All of New Zealand is below the cyclone belt. We spent the last two cyclone seasons in New Zealand. This year we have decided upon Australia and have made Brisbane our temporary home port. We arrived at the start of the summer so there should not be too much of a transition from tropical heat to subtropical warmth.

Warnings

These days cyclone warning services make it much easier for cruisers to keep abreast of what is happening. But again the South Pacific is somewhat different from other areas, notably the Caribbean. Typically hurricanes form in the Atlantic and track west, taking several days to develop and reach the islands of the Eastern Caribbean. In the South Pacific the cyclones form over the islands, typically the Solomons, Vanuatu, Samoa and Fiji. Although the Met services watch developments (usually associated with the South Pacific Convergence Zone) and provide warnings, it can leave yachts with little time to act, especially if something develops unexpectedly, catching the forecasters out, as sometimes happens. (See the forecast below).

NOTES

Cyclones (Pacific), monsoons (Indian Ocean and Australia), hurricanes (Caribbean) and typhoons (Northwest Pacific) all refer to the same thing--deep powerful depressions that form in the tropics. The different names simply reflect different linguistic origins.

Be aware that there is some evidence that the number of cyclones per year is increasing and that the season is lasting longer. It seems as if it may be extending beyond the normal end of the season. In El Nino years the number of cyclones in the Pacific may increase and they move eastwards somewhat, e.g. affecting the Society Islands.

Bob McDavitt's weekly Weathergram is e-mailed weekly. The following describes the first Cyclone of the 2001/2 season

WEATHERGRAM
Issued 2 Dec 2001
YOTREPS

Bob McDavitt's ideas for South Pacific sailing weather. (Standard disclaimer: Weather is a mix of pattern and chaos, these ideas come from the patterned world of weather maps, so please fine-tune to your place).

Tropical Cyclone TRINA briefly had a name --and a ring of gales around it ---just east of Rarotonga yesterday 30 Nov/1 DEC UTC. It has mucked up my good record of spotting these things in the weathergram beforehand. And it counts as a NOVEMBER cyclone, and means that the records will show that this year the cyclone season started in November. The pressure at Rarotonga airport has just bottomed out at 999 and peak southerlies were sustained at 25 kt and gusting to 55. No damage reports yet. It has built the seas up to 3 ocnl 4 m around the Southern Cooks and should radiate 2.5 ocnl 3.5 m swells downstream as far east as NZ in next few days.

The Big High near Chatham Islands is still there and is expected to linger again this week, weakening and shifting North to allow the "low that was TRINA" to go south then SE. This low may go through another period of deepening near 30S 155W on Thursday UTC, avoid. The huge squash zone that lies on the northern side of this high extends from 150w to 180, mainly between 20S and 30S, and laps into the NE flow that is over Northland. Avoid this squash zone. Waves are rough and occasionally rogue.

In the Tasman Sea, south of 30S: one low is expected to move from Tasmania on Monday to South Island by Thursday, and another should be deepening east of Sydney on Friday. Avoid. This all helps to weaken the trade winds between New Caledonia and Australia, and maintains a northerly flow on the Queensland Coast. However a thundery southerly change might get there by next Sunday 9 Dec.

TRINA formed on the southern end of the SPCZ which has been arcing from 5 to 10 South between 170E and 170W then SE to southern Cooks. There is another branch over French Polynesia with hints of rotation at places like 20S 135W. But these are not expected to develop. There is a new branch of the SPCZ forming from the south end of the Solomons to the area north of New Caledonia and west of Vanuatu. This has potential, but computers so far are not impressed. Check if sailing nearby.

The terms used here are more fully explained in the METSERVICE Yacht Pack. Feedback is encouraged to mcdavitt@met.co.nz Bob McDavitt .