Probably things will turn out differently after all

The National Oceanic and Atmospheric Administration, NOAA for short, is a U.S. government-related organization that operates a weather server that reliably predicts tropical cyclones, their tracks, intensity and strength. The National Hurricane Center NHC page displays developing cloud formations, tropical depressions, storms and hurricanes. The recent example of potential storm "Two" shows that this is not always easy. 

Cloud formations

Since last week, dense cloud bands have been moving south of Cape Verde, from the west coast of Africa, towards the South American continent. Initially, this is nothing unusual for this time of year. As this band of clouds moves roughly along the fifth parallel of latitude, the Earth's Coriolis force is not sufficient to turn this cloud formation in and form it into the distinctive vortex that makes up a hurricane. A rule of thumb says that the force is sufficient from the tenth degree of latitude. This makes it all the more difficult for meteorologists to make reliable predictions, south of the tenth parallel. By the way, all the other forecast models that are floating around on the net, in terms of hurricanes, are based on NOAA. However, the potential hurricane "Two" did not do the meteorologists, for a long time, the favor of getting beyond this tenth degree of latitude. Since the hurricane had been announced, but the cloud band continued to move toward the Caribbean, and still no clear statement could be made, a so-called "Hurrcian Hunter" was sent out to assess the situation on the ground. A "hurricane hunter" is an airplane that flies into the cloud formation and carries out measurements, in order to be able to draw conclusions with the data, on the further development. 

Anchorage shortly before passage of "Two"

Admittedly, the website still warned of a tropical storm. Only the small print and the symbolism indicated that it was not a storm, but that the formation had the potential of a tropical cyclone. The "Hurricane Hunter" was also unable to make a definitive statement on the spot, so it was decided to keep the warning in place. The track of the depression was along the southernmost predicted line, immediately along the Venezuelan coast. Initial reports from friendly boats in Grenada, indicated heavy rains and moderate winds. Depending on what weather model was used, the forecast for Aruba was 22 to 25 knots, and up to 45 knots in gusts. When the formation passed south of Aruba on 06/29/2022 at about 6:00PM, the anemometer showed 11 to 15 knots and in the rain squall a maximum of 25 knots. The rain kept within limits, so I could just fill a 5 liter canister with rainwater. Since we had experienced in Carriacou and French Guyana, without warning, already quite different precipitation. In the meantime, the cloud formation had crossed the tenth parallel. But there are two more aspects that significantly reduce the probability. First, the water temperature must be above 28°C for a cyclone to develop, and second, land masses are an obstacle. For weeks, meteorologists have been indicating a water temperature of 27°C for the Caribbean Sea, on the coast of Venezuela, and the track followed the South American coast. In this respect, the probability of the development of a tropical storm was very low. If you look more intensively at the NOAA site, it never claimed anything else, and in the end it is better to be prepared in any case. 

Wind data during passage of "Two"

However, I also wonder what happens in the many cases where no warning is issued, or it tends to tickle at 30 knots for days and the weather report doesn't even half predict it. Also, I wonder if it makes any sense at all to define a probability for cloud formations around the fifth parallel. After all, the probability was rated by NOAA as >60%. Whether "Two" will develop into a tropical storm on its way to Nicaragua, between the 75th and 83rd degree of longitude, remains to be seen. NOAA is much more cautious in its forecasts, by the way, with the following wave. Although this wave has crossed the tenth degree of latitude much earlier than "Two", the potential of this tropical wave, below 40%, is estimated at 10%. That this wave has much more potential, however, is shown by the direction of migration to the northwest, the path over open water and the direction towards warm water. I would like to talk to the responsible persons how such forecasts are made and which approval procedure they go through. That would help me to better assess the forecasts. A not exactly insignificant factor if one is dependent as a sailor on the weather. In this sense, always fair winds and keep a stiff upper lip.