From 35 degrees west and approaching the chain of Caribbean Islands its movement is more often slightly north of west (say 280 to 290 degrees true). By the time the ‘tropical wave’ is touching the chain of Islands its northern and southern edges will probably lie between 20 and 10 degrees North. It is affecting the whole of the Leewards, Windwards and the Virgin Islands.

Caribbean Islands

The moment a ‘tropical wave’ reaches the chain of Caribbean Islands the wind will increase and turn anti clockwise and back to north of east. With the passing of the leading edge of the wave a series of so-called ‘line squalls’ with heavy rain will be experienced. A ‘line squall’ is a sausage-roll of very fast moving clouds of which the bottom is colored unfriendly black. This sausage that obviously grows bigger the moment it closes in presents gusts for between 25 and 45 knots. Sometimes for a short time in the 50-60 knot range, if the ‘wave’ is pretty strong. Also ‘thunderstorms’ or ‘rainstorms’ might trouble and even in inter-island passages waterspouts occur. No way to explain that you must try to avoid waterspouts at all costs because of the quite devastating winds in the small eye of maybe 100 meters in diameter.
After the ‘wave’ passages the wind shifts clockwise and veers south of east and in the case of a strong wave it will blow pretty strong for a day. Than the normal 15 to 20 knots northeasterly trades will take its place.

Tactics

It is wise to sail out of a tropical disturbance like a ‘wave’. Just choose a northerly, southerly or easterly course like for that moment being the most convenient. An easterly course will bring you the quickest out of the disturbance. Do not choose a southerly course if you are in a wave close to the ITCZ. The chance you will end up in a tropical depression that just forms at the southerly tip of the wave which is the closest to the unstable ITCZ might be available. Remember that this could happen within hours, depending the strength of the wave and the convection activity.
In the back of the ‘wave’ you will experience stronger winds. However, the likelihood that you might encounter a tropical unwanted present like a tropical storm is at this position zero percent. Just continue your course as desired. Whether a wave is weak, moderate or strong you have to determine by yourself. A weak ‘wave’ shows less convection and a more quiet weather pattern: less rain, no ‘rainstorms’, little or no gusts, a few high building Cumulus clouds and little convection. The chance a weak ‘wave’ disappears is present. In addition, the contrary might happen as well. The ‘wave’ might grow stronger and could explode in a disturbance. No one can tell. It all depends whether God decides there has a lot of vacuum cleaning to be done.

It might be clear that a tropical storm or a tropical cyclone will be born the moment the next parameters might be present:

• The presence of a ‘tropical wave’ or another disturbance, not just a ‘squall’.
• Seawater temperature of at least 27 degrees.
• An area of low pressure.
• Convection. The air at high altitudes is unstable and full of moisture.
• No strong wind changes in the upper level atmosphere.

Next time we present the birth of a tropical cyclone, and for so far existing, a cyclone tactic. I describe the tracks of some famous cyclones Maaike and I met.