That Hurricane!

How To Keep Track Of

~)Me Useful Hints

By Jps

I7ITH another hurricane season ? approaching, the time seems opportune to state a few eful facts on a subject of much terest to residents of the South est Pacific. There are some inters regarding the behaviour of irricanes in this area which, once iderstood, provide Islands resi mts without a barometer with lidance in determining whether not they are going to be struck, id how severely. [t seems necessary to stress that irricanes are not winds that sud nly spring up from nowhere, and en die down after doing their rndest in some particular area, le hurricanes that affect the New sbrides, New Caledonia, Fiji and e Cook Islands—the groups most bject to these visitations—are rn, usually, over a period of days, the vicinity of the Equator. rhey all have this general habit: ley consist of winds circulating rally, always in a clockwise direc n, inwardly and upwards round central “eye” which may be from reral miles to over 20 miles in imeter. The whole system will a couple of hundred miles in imeter —and, once formed, it lally starts to move, almost pays in some southerly direction. 3o here is the first pointer: If .ir radio reports a hurricane newhere hundreds of miles away the north, north-east or north st of you, be on the alert. If the rricane is centred anywhere south you, the chances are very small it you will be visited by the beast. 0 understand the wind-system of a hurricane and to predict ;h reasonably accuracy what its ection of movement will be, only d things are required—a map or irt of the general area of the ath Pacific within, say, 500 miles your location, and a piece of sue paper or celluloid.

Depending on the scale of the p, draw a circle with a diameter say, 500 miles on the tissue Der; then draw a spiral line, in clockwise direction, from the ;er edge of this circle in towards centre, so that, in thus spiral g inwards, it circles the centre if a dozen times. Draw little ow heads at intervals along this e, facing in a clockwise direction; 1 there you have, approximately, i wind system of the hurricane. fou must now realise that not y is the wind circling round the itral eye—which you can draw -but that the eye itself, and the ole thing, is almost certainly ving in some southerly direction anything from 5 to 25 knots.

The present meteorological facilities in the South Parific are generally inadequate to permit an accurate determination of the posi- Sfi}. ° f o *iJ5 w ce £ tr ,f f °on the hurricane very rapidly, if at all.

The predicted track may be, say, 30 miles to one side of the actual track taken by the storm. Therefore, it may well be that you, living on some outer island, will be much better placed to determine the true track in your region, than is the weather office the point where the forecasts are issued. And it may be taken for granted that you are interested in whether or not

the full force of the blow is going to hit you.

IF you are, get outside smartly and note with reasonable accuracy the direction from which the wind is blowing, as soon as rumours of a hurricane are circulated—and continue to note at frequent in tervals thereafter.

Let us suppose that you find the wind is easterly. By juggling that piece of tissue paper it will be at once evident that the centre of the storm can only be in one possible direction from you somewhere north, or a little west of north.

It will also be evident that if the wind continues to hold in the east, or in any direction from east to north, and gradually increases, it is an almost certain sign that the hurricane is heading directly

for you. So long as the direction of the wind keeps altering the centre is not heading toward; you.

But it is a popular fallacy that most damage occurs in the uath cl the eye of the storm. A little thought will show you that the winds are going to be strongest on the right-hand (or eastern) side ol the hurricane’s centre—because, il the hurricane is moving south ati say, 15 knots, it is clear that those 15 knots will be added to the force of the northerly-quarter winds on that side of the whirling air mass —just as the 15 knots will be de ducted from winds on the left (oi west) side of the storm.

Thus, if the eye (or calm centreX is ten miles in diameter, and the winds spiralling round it have a 50knot velocity, an island east of the centre will experience 75-knot winds while one, say, of fifteen miles to the west will experience only 35knot winds.

And here it may be noted that a place directly in the track of the above hypothetical hurricane would! after suffering a violent and in creasing blow from east to north] have a calm respite for 40- minutes —while the 10-mile eye passed at 15 knots—and then, on the othen side of the storm, the winds would: strike with violence from south tcc west, gradually diminishing as the storm moved away.

Our piece of tissue paper will, clearly demonstrate this. It will, also clearly demonstrate that as hurricane does not approach fronr the direction of the wind—far fronr it —iust about 90 degrees from it.: in fact.

SO here are the cardinal rules fon the home forecaster. Once as hurricane has been reported: anywhere north of your latitude,; start to take frequent note of thea wind. ® If it remains in the sames direction and steadily increases, thea centre is heading towards you. e If it gradually moves round! from southeast through east, and increases, you are on the east on “bad” side, and the centre will passa somewhere close to the west of you. j • If, on the other hand, the windt moves from southeast through southr towards the west, and increases, thee centre is passing east of you andfc the blow will be less severe. • If the wind, after blowing veryv hard, suddenly drops, do not bee misled into thinking the blow isa over. You are clearly in the centres of the storm and the direction willU reverse and the force soon increases again, probably within an hour.

Those are the general rules. But„: once in a while, a hurricane playse tricks. Instead of holding its usuall, south-westerly, southerly or south easterly course, it dives back on itse track, or runs off to the eastward!: for a while, or becomes Sometimes when the latter happensia it “deepens”—the central pressureb

ills and the circulating winds in rease in velocity. This, of course, ives the false impression that the urricane is approaching.

But, by and large, that map and iece of tissue paper, plus an ccurate sense of direction, will tell du a great deal about the behaviour f that hurricane, and let you know hen or whether to prepare for le worst.