The Great Southern Route : 2010 - 2011
WEATHER ROUTING 032 | GSR in the strongest surges. (see Figure 1A). During April and May, and again in September through early November, the cold fronts are weaker and less frequent, tracking across the northern Red Sea and Persian Gulf about every 4-5 days, also tending to not push quite as far south. The ridge of high pressure that builds over the eastern Mediterranean is also weaker during the spring and autumn; and therefore the arctic air that funnels through these seas in the winter is moderated. Hence, the north-northwest wind surges occur less often and are weaker than their mid/late fall and wintertime counterparts. From May through early October, a thermal trough of low pressure generally develops from northern Sudan northeastward to the central Arabian Peninsula, and from there extends northeastward across the Strait of Hormuz and along southern Pakistan. This weather feature changes little in strength but does fluctuate its orientation during the summer. For instance, if the thermal trough is across the central Arabian Peninsula and a ridge of high pressure builds over the eastern Mediterranean Sea, then northwest winds will become enhanced from the Gulf of Suez southward to approximately frontal passages, with post-frontal passage NW winds of force 5-7 common. Winds as high as force 8-9 possible during the strongest NW wind surges (which are known locally as "Shamals"). The strongest of these winds tend to occur along the SW Iranian coast due to the funneling effects of the mountainous terrain of Iran itself. The winds then "wrap around" the southern coast of Iran and through the Strait of Hormuz, becoming westerly to southwesterly in nature in the western side of the strait, and returning to the original northwesterly direction as they exit the eastern side into the Gulf of Oman. Unlike what is found within Bab El Mandeb, the wider space within the Strait of Hormuz reduces the funneling effects and wind speeds within the strait often are fairly close to what is ongoing west of the strait. The 'fetch" within the Persian Gulf is somewhat less than within the Red Sea, so seas tend to be slightly lower here during Shamal-related NW wind surges. Typical seas range 2-4ft in normal northwesterly winds. Ahead of fronts, short- period and "choppy" southerly 4-7ft seas occur near the northern end of the sea, and following frontal passages NW seas build to as high as 8-10ft in the southern sea with 10-13ft possible THE WEATHER CONDITIONS across the Red Sea and the Persian Gulf, as well as the northern Indian Ocean, as we will later discuss, alter significantly between the winter and summer months. From late November through March, strong cold fronts track across the northern Red Sea and the Persian Gulf approximately every 3 days. Behind these cold fronts, cold air funnels or "channels" through the narrower waterways through the Gulf of Suez, and farther south into the Red Sea to approximately 18N, and finally across much of the Persian Gulf and into the Gulf of Oman. All of this occurs as a ridge of high pressure builds across northeastern Egypt and the Arabian Peninsula. As a result, enhanced north-northwest winds surge across the Gulf of Suez and the northern Red Sea of approximately Beaufort Force 5-7 and swells will build up to 8-12ft. Behind exceptionally strong cold fronts, winds will increase up to sustained gale force (Beaufort Force 8-9) particularly near the Gulf of Suez and swells will build up to 10-15ft. Average wintertime winds within the Persian Gulf are from NW, generally at speeds from force 3-5. Ahead of cold fronts, winds turn southerly and can increase to force 5-7. Winds then veer following By Amanda Delaney, Mark Neiswender and Brian Whitley of Weather Routing, Inc. General Weather Conditions for The Red Sea and Persian Gulf Planning a trip to any of the exotic islands in the Indian Ocean, India, or Australia would entice the imagination of any mariner. However, if one does not prepare for what lies ahead, a dream vacation can turn into a horrendous trip. That is why for a mariner it is very important to be knowledgeable about the weather, or to receive assistance from professional Marine Meteorologists, or a weather routing service while underway in order to transit on the safest and fastest route possible. To that end, this article will discuss, in detail, the general weather patterns across the Red Sea, northern, and southeastern Indian Ocean for the entire year. The best times for transiting will be summarized in order to provide the smoothest voyage possible (or if actions need to be taken during the more unfavorable seasons).
2008 - 2009
2013 - 2014