Weather tips

Atmospheric fronts often give the clearest signal about the looming danger.

What is an "atmospheric front"? Basically, it's a place where warm and cold air masses collide, with a boundary that's sloping against the surface of the Earth. There are four types of fronts: warm fronts, cold fronts, occluded fronts, stationary fronts. Now there's a fair question: how can the front be warm or cold, if both have masses of air of different temperatures?

The answer is quite simple. Since the front is always in motion, the front that moves towards a zone with cold air and brings warmth is considered warm, and vice versa. An occluded front is formed at the junction of a cold and a warm front when the warm mass of air no longer touches the ground. A stationary front is essentially a slowing down warm or cold front where the air masses have practically stopped moving.

What can a yachtsman expect from such global weather events? First of all, weather changes. But how dangerous can it be?

Let's start with the warm front. The main trouble - sustained rainfall. The first signs of its approach are cirrus and cirrostratus clouds. Of course, the wind increases, but usually not too much. Wind direction suddenly changes. Pressure gradually drops and reaches the lowest point behind the front. So it's only worth going back if you forgot foul weather gear.

A cold front is much more dangerous. You can tell by looking at it: a solid wall of dark thunderclouds. Pressure can drop sharply before its approach. 'Barometer falling' portends way more trouble than just the need to fix the device.

Cold fronts are divided into two kinds. The first one is not so dangerous. It moves slowly and warm air gradually moves upwards all over its surface. The second one moves quickly, often with a noticeable acceleration. The warm air in it first moves down to a height of one and a half to two kilometers, and then rises sharply.

As the front approaches, the wind intensifies noticeably, as with any thunderstorm, there are sharp increases. However, the situation behind the front is even more serious. Wind speed at gusts can easily be dangerous. A sharp change in wind direction follows.

To go in such a storm, even on a well prepared boat, is not the best decision. A good example is the infamous 1979 Fastnet Race, when only 85 out of 306 yachts reached the finish line. 5 yachts sank and 19, in disrepair, were abandoned by crews.

Subsequent analysis of the tragedy showed that one of the reasons was a sharp change in front trajectories which was simply impossible to predict at the time. Even today, a long term forecast is often impossible. But within two or three days it is extremely accurate. Therefore, before going out to sea it is necessary to get acquainted with the meteorological situation both on the route and in its surroundings. If there is satellite internet on board, it is worth doing it twice a day.

In addition, the CAPE index, which stands for Convective Available Potential Energy, can help. The higher it is, the more likely weather disasters are. If the values are negative - it's calm. From 0 to 1000 - there is a probability of small thunderstorms. From 1000 to 2500 - strong thunderstorms with precipitation can be expected. From 2500 to 3500 - a squally wind, powerful thunderstorms with hail. After 3500 one can start preparing for a natural apocalypse.

Thunderstorms at sea are extremely dangerous! Unfortunately, there's still no way to fully protect a boat from lightning. It is possible to lay a special cable on the mast, directly in contact with water at the keel. But firstly, it is necessary to do it in advance ashore, and secondly, its efficiency is unpredictable. But what can be done on almost any boat - putting all electronic devices that can be dismantled into a shielded metal container. Or simply in a pot tightly covered with a metal lid. Then they will not only survive close strokes of lightning in water, but even a direct hit in the mast. Such a situation is very unlikely, but one should be prepared for a fight. Though try avoiding it as long as you can.

Now there's the occluded front, which is also divided into warm and cold - cooled air replaces cold air and the other way around. Each of them has the features of the original front - warm or cold - with all their characteristics. So the cold one can definitely cause you problems. Though not as significant as the "original" cold front.

The stationary front is the calmest. The masses of warm and cold air are kind of resting after a riot. Since the front is a product of slowing down of a warm or cold front, the weather in it will correspond to that which its ancestor brought. However, in any case, there should be no more strong winds.