Weather forecast: a guide to interpreting natural phenomena when we are sailing.
As time goes on, it becomes a habit, a sort of conditioned reflex which leads us, even in the city, to look up and find in a cloud or a smell something which is going to change.
Maybe nowadays, being provided with all we need to have a weather forecast at home, understanding weather and its signs belongs to the wide lands of pleasure rather than to the fenced spaces of necessity.
However, especially in a scenery like the Mediterranean Sea, where weather variables are countless, a comparison between what our nose and eyes suggest and what we have read can give something more to make the right choice and thus to have weather forecast that can anticipate the advent of probable natural phenomena during navigation.
Nature give us many informations and signs. Clouds, humidity, air transparency and sea movements in a harbour form a self-perpetuating language we have to listen to.
Our dialogue with nature can start in the harbour, before sailing off. If we are in a zone not particularly subject to tidal ranges, we can observe what happens at the water level in the harbour. If we notice a significant increase, it is the sign that wind is blowing from the sea and that waves are increasing. Vice versa, if water level decreases, this means that wind is blowing from the land and that a under-coast-navigation will be in calm waters.
Always in the calm waters of a harbour or near a roadstead, night is the best advisor. In summer, when the deck is covered with millions of humidity drops, it indicates that everything is ok, good weather is not changing and tomorrow will be a nice day. But if we are enjoying an unusually dry evening and our cockpit is perfectly dry, we’d better to examine in depth: something is changing, especially if we are near some elevations.
Night is, of course, the best moment to look at the sky. Let’s take some seconds to be more analytical and let’s look at the stars: if they are particularly sparkling, and we haven’t just fallen in love, this means that air is more transparent because of some high strong winds which will probably reinforce the water level,too.
The moon, too, can inform us about the coming day. The halo surrounding it has inspired several proverbs in all languages and dialects: “ Halo around the sun or moon, rain or snow soon”, for example.
Popular proverbs, forged by experience, indicate a precise phenomenon: the presence of cirrostratus clouds which create an optical effect. Since cirrostratus clouds are often associated to an increase in humidity, the moon and its halo are probably warning about the arrival of a warm front and rain in very few hours.
Weather forecast depend on many natural elements. In summer, breezes are another important source of information. The raising warm air which gives way for the colder one is a sort of play between land and sea that, if it is not disturbed by an unexpected event, is very regular: at night, breeze blows from the land to the sea; during the day, from the sea to the land. A strong intensification of breezes or a sudden end of them indicate an anomaly. So, we have to check the situation on the web in order to understand what is changing.
A sudden change in wind direction and temperature is another important alert. It can indicate many phenomena, like a storm, we can interpret by observing clouds.
Another situation which should activate our senses is when wind, after being fresh, starts to jump from quadrant to quadrant. We are probably next to the centre of a depression and wind will become stronger.
Clouds take shape, run, disappear, change their shape. Charming exactly for their volatile mood, we don’t have to classify them according to their height, shape and composition. We only have to observe them and register what happens.
When we sail along a coast in summer, for example, it’s easy to see some white clouds generated by the condensation of the raising warm air. It’s a situation of good weather but it’s better we keep an eye on them, especially after a long period of high temperature.
If they start to develop upwards and take the typical shape of an anvil, they are getting cumulus clouds. The air on the sea level will travel towards them and it will feed them. Then, after a short dead calm, it will reverse its direction. A storm will appear with all its strength, accompanied by gusts, rain and some litghenings.
If, on the contrary, we notice some oval clouds, especially on the leeward side of elevations, we can be rather safe that a strong wind is blowing in the surroundings and it might reach the sea level.
Scattered ceiling, water in basins. We can trust in proverbs to interpret the message of cirrocumulus clouds, that is the clouds which appear in big groups with small pieces of visible sky, like a flock. They indicate the presence of high wet winds and that a perturbation is slowly coming.
The same message of cirrostratus clouds which create a halo around the moon at night and around the sun in the day. Also in this case, especially if temperature is getting warmer, clouds suggest to prepare a raincoat because a warm front and rain are coming.
Vice versa, a sky studded by white bolls, with wide spaces of blue, wants to reassure us about the coming sunny day.
After all, even a summer day with very little visibility, opaque sky and a lot of humidity, is the sign that weather is stable, with flat sea and no wind. But if this blanket suddenly disappear and air gets clearer, a gust of wind might occur.
We could go on for hours to observe and interpret clouds, but we also need to look at waves. It has certainly happened to each of us to ask ” Where does this sea come from?” while facing a long wave unrelated to the wind blowing in that moment or even in a situation of total calm. If it is not old sea, the answer is easy: in the direction where the wave comes from, the wind is probably becoming stronger and this is a certainty if the wave quickly becomes shorter and steeper.
Clouds and skin, eyes and waves are really some refined tools to recognize and understand natural phenomena. We have to activate our senses, link them to our memory and register what we see.
Without forgetting to consult weather bulletins carefully before sailing off, a way to have reliable weather forecast that can provide a comprehensive anticipation of natural phenomena that might occur while we are at sea.
