The Great Southern Route : 2010 - 2011
WEATHER ROUTING 250 | GSR for westbound transits is in finding the trade winds and avoiding wind surges for the best possible ride. This means avoiding the passage of cold fronts late in the year and during the winter and early spring, thereby minimizing exposure to higher NW-N-NE winds. By allowing for weakening of the high pressure ridge farther west (normally in advance of cold fronts), lighter NW-NE winds and lower, longer-period NW-NE combined seas will allow for a smoother passage across eastern waters, east of 115W-120W. Once farther west and in the trades, travel typically becomes easier. Winds and seas are more or less all following, and the main concern, particularly for less "heartier" vessels becomes higher NE-E winds/combined seas, as high pressure ridges merge late in the year and during winter/early spring. For such lengthy transits across this region, wind surges are almost always a factor to consider, especially during this period. Of course, while summer means less wind surges and overall lighter conditions, it also means one will have to be mindful of the tropics, particularly those cyclones that form in more southern (near/south of 20N) and western waters. Wide "searoom" and sufficient fuel range of vessels will certainly afford route alterations for safe passage around such systems. Panama Canal to the Galapagos: The weather in this part of the world tends to be (for the most part) rather quiet. The main concerns over the course of the year will be enhanced N-NE winds from late fall through early spring (November through April) and squalls, especially later in the year (later spring/summer). "Periodic" (1-2 day duration) higher N-NE winds mainly occur across the Gulf of Panama and vicinity, occurring as large high pressure ridges build into and across much of the western and central Caribbean from the north and west, interacting with a rather persistent thermal trough (low pressure) along/near the northwestern coast of South America. Higher wind surges can occur during the spring, summer, and early fall, but are less pronounced, meaning gale force winds are less likely to occur, and are mainly due to a westward building of a semi-permanent high pressure ridge, building into the western Caribbean from the north and east. Looking farther south toward the Galapagos, the main weather feature in place is a broad, elongated trough of low pressure, oriented east to west across the equatorial Pacific. It is on the northern extent of this trough that we find the so-called "Inter-tropical Convergence Zone" (ITCZ), where N-NE-E winds further north "converge" with SE-S-SW winds further south, and where clusters of showers and squalls develop and move in a general westward days at a times over a given location. Winds will actually tend to vary from E-SE-S becoming "gentle" or "moderate", speeds mainly from force 3-5 and no more. Combined seas, in turn, will become more E-SE in direction and abate, generally not exceeding 6 feet, especially in more prolonged lulls in winds. The largest of these combined seas will tend to be mainly swell, with little wind driven "chop" on top of the swells. Once you are south of 10N, you are getting close to and within the "Doldrums". Winds become lighter, and vary from NE-SE-S, with NE-E winds found north of the Equatorial Trough axis, and E-SE-S winds found further south. Wind speeds within this region tend to be from force 3-5, and near/below the low end of this range along or very near the trough axis. Combined seas become long-period and tend mostly swell with NE-SE-S seas averaging from 3-6 feet. Slightly higher long-period sets (generally 1-2 feet higher) will occur in higher trade wind surges, typically in NE-E sets from high pressure to the north, or E-SE-S sets from ridging further south, in both instances occurring when ridging is stronger (toward/during the winter season). Disorganized squalls within the Equatorial Trough will bring localized periods of higher winds and combined seas (both in and near squalls). Squalls often bring periods of reduced visibility, with heavy/severe squalls bringing visibilities below 2 nautical miles at times. Prevailing currents more or less will fall in line with dominant wind directions. The already-mentioned California Current runs from north to south more or less parallelling the west coast of the Baja Peninsula and found just offshore. Increases in current speed and a southward "expansion" of the current will occur during stronger wind surges, associated with the passage of cold fronts during the period from late autumn through early spring. Farther west, currents become a more favorable southwest to westward moving direction. As one might imagine, the key in finding optimal weather winds and routing 115W-120W, generally "moderate" to "fresh" in intensity. However, surges of higher winds will occur, mainly during the late autumn, winter, and spring months, as surges of cooler air move in behind cold fronts. Large NW-N-NE swells will accompany wind surges, often near and in excess of 10 feet, though will tend somewhat lower and longer-period in more southern waters. Easing of winds and an abatement of seas will occur as ridging further west weakens, and as cold fronts approach the region from the north and west. NE-E trade winds are dominant further west toward the Hawaiian Islands and in more southern waters (to 10N), speeds generally no more than force 5-6, with combined seas generally as high as 7-8 feet. However, merging of high pressure ridges will bring about periods of higher NE-E winds, which at times will reach gale or near gale force (force 7-8), along with larger NE-E swells, as much as 3-5 feet higher than those mentioned under "normal" circumstances. The approach and passage of stronger cold fronts north of the area will bring breaks in the NE-E wind/sea regime, normally lasting for 1-2 Figure 4: Typical summer weather pattern in the Eastern Pacific. Figure 3: Typical winter weather pattern in the Eastern Pacific.
2008 - 2009
2013 - 2014