During the last twenty years, meteorology has made significant progress thanks to the extraordinary contribution of satellites, modern telecommunication systems and weather models.
However, despite all these technological improvements, being able to establish the forewarning signs of a weather change is still the key for a captain to determine the safest and most favourable route.
Safe anchorage but heavy weather conditions just outside the harbour
Yachtsmen have to look carefully at the sky and sea state on the horizon, trying to determine whether marine weather conditions will remain manageable or if wind and wave heights are on the increase, making navigation more difficult.
Relying on accurate and updated weather bulletins is important especially in the case of Mediterranean where a number of variables cannot be predicted even by the best forecast models, taking even the most expert captain by surprise.
The awareness of the limits of marine weather information contributes to make a better use of it.
It is to be stressed that there are various sources of meteorological information (for the entire Mediterranean area) and this allows a yachtsman to rely on a more detailed and accurate service on how conditions at sea are changing.
It is rather unlikely that a gale is not forewarn by a public meteorological service and this is certainly re-assuring.
In this way, instead of spending too much time comparing weather bulletins issued by various sources, a captain should allocate an amount of time to study the main meteorological information acquired, analysing them carefully and completing them with his own weather observations, before making up his mind whether to port or anchor.
To sum up, there are basically three ways to gather weather information as follows:
Case 1
A yachtsman not believing the accuracy of weather bulletins, whether it be for presumption or mistrust, maybe through experiencing adverse meteorological phenomena which had not been correctly forecast.
Case 2
A yachtsman using a weather service as a useful auxiliary assistance which has to be interpreted on the basis of his own observations and adapted to his navigation plan. Making the right evaluations is obviously very important when weather parameters like wind speed and wave heights are just below the critical threshold and the captain is under pressure to reach a destination by a specific date or time.
Case 3
A Yachtsman leaving a port only when marine weather conditions shown by bulletins are extremely good.
The new Varazze harbour (44°21’15’’, 008°34’12’’E), close to Genoa, Italy
Independently of any consideration made by a forecaster, every navigational decision has to be ultimately made aboard by the captain, whether he deals with a small sailing boat or a yacht, because nobody knows better the characteristics of the yacht than the captain, together with all issues concerning the crew, the guests, maintenance of the yacht, the availability of berths in a port, fuel consumption issues and so on.
It is my view that the most coherent consideration is the least extreme situation. Being wiser to study and look at weather information in a critical way and trying to understand how a forecast for a certain area can be subject to significant weather changes on a local basis.
It is the captain’s responsibility to acquire all the elements allowing him to choose the best time to leave or stay anchored and the safest or least unfavourable route.
After professional navigation across the Mediterranean and the Atlantic for several years, I realised the importance to understand weather at sea which is like a useful onboard equipment to be used as the key tool to ensure the safety of the yacht and the crew.
“Navigational Meteorology” is about choosing the route in relation to the actual and forecast marine weather conditions, the characteristics of the yacht and the crew. Studying the weather aboard a yacht is like being on a mobile weather observatory in relation to the position to weather systems which can be approaching, passing over or moving away from the yacht.
Because a yacht can find itself in any kind of weather conditions, some simple practical advice is outlined here below:
- weather information is extremely important for navigation
- consulting weather bulletins and updates is the captain’s duty and not an optional task
- a weather bulletin does not just have to be considered like a traffic light showing green for no warning, or red for gale warning; it needs to be carefully interpreted and adapted to the navigation plan by the captain or first officer.
The observation of weather at sea must be made carefully, highlighting any discrepancy related to the forecast. Last but not least, the captain should consider that any forecast, no matter how accurate, is based on a statistical analysis; whereas observations aboard have the extraordinary value of representing actual conditions which are truthful.
For all these reasons, the captain should bear in mind that a disagreement between observed and forecast information can occur, and this could lead him having to make adjustments or significant changes to the original route.
Positioning a yacht in relation to the weather systems and obtaining practical indications for navigation is useful for a captain when asking himself the following questions:
- Have any weather warnings being issued?
- Is the weather settled or unsettled?
- Is the weather or sea state improving or deteriorating?
- What is extent of the improvement or deterioration?
- What are the prevailing winds? Northerly or southerly?
- Are the winds favourable or contrary to your route?
A simple way for answering the a.m. questions would be to interpret the weather patterns in a schematic way in order to reduce the margin of uncertainty, which will in turn make navigational decisions easier.
It has to be stressed that the sensitivity to weather changes at sea derives from experience, and the attention a yachtsman pays to the observation of weather phenomena is important, especially when critical weather conditions occur.
It is a heritage that can only be acquired by navigating and anybody can cultivate a passion for weather forecasting, even by studying and adopting simple, practical rules.
Technological progress has rendered weather routing easier and safer, but there is nothing like inferring a weather change through the indication of falling pressure on a barometer showing an approaching depression, or noting an increasing swell originated by a wind blowing strong over an area located a long distance away from the place of observation.
Some of sources to use as a reference for are listed here below.
Sea state over the Western Mediterranean, courtesy of FNMOC
Synoptic chart of North Atlantic, courtesy of NOAA Fax and the Met Office
Example of the GMDSS Forecast area III for the Mediterranean, which represents one of main source of weather information, courtesy of Meteo France
Global Meteosat Satellite view (GOES-10, GOES-12, Met-7, Met-5, GOES-09), courtesy of Eumetsat
Meteosat satellite view of Europe (channel 7), courtesy of Eumetsat
Captains can contact Navimeteo writing to routing@navimeteo.it to obtain information about the most suitable weather services for their needs and to enquire about the technological systems available to acquire weather information.