By Kyle Petroziello
Springtime marks a changing of the guard toward more favorable weather in the Caribbean Sea and north into the Atlantic. The stronger and more active winter pattern begins to regress, opening windows for sailors across the Caribbean to begin their transits elsewhere for the summer months. These destinations most often include the U.S. East Coast and Mediterranean Sea.
As we “spring forward,” cold fronts approaching from the west become less frequent, on average reaching the U.S. East Coast every 4-6 days. These also shift farther north, to extend southward only as far south as central Florida. From there, they tend to weaken in the western Atlantic waters, while also lifting northeastward to follow the main gale track which migrates farther north during these months.
Secondary lows or gales will sometimes develop, usually forming along the Southeast U.S. Coast. These tend to deepen and continue northeastward toward the Canadian Maritimes and merge with the main gale track. However, occasionally these lows/gales can become “cutoff” and stall near Bermuda or farther east between Madeira and the Azores. When this occurs, they will meander in place for about three to five days before moving east or northeast ahead of the next cold front. Alternatively, these systems can dissipate prior to becoming picked up by the next cold front.
The main feature driving conditions for these passages is a subtropical high-pressure ridge found in the central Atlantic. The axis of this ridge typically sets up between 31-33N, with associated ridging extending southwestward toward the Leeward Islands, and farther westward to the Southeast U.S. Coast. The full extent of this spreads along/south of 40N to 15N and along/east of 70W through the central Atlantic. Weak transitory high pressures will follow frontal passages, diving down from Canada and tracking east-southeastward off the East Coast, eventually merging with the stronger central Atlantic high. At times, a portion of the ridge will break away and become a new high center moving northeastward toward the Iberian Peninsula.
Farther east, a thermal trough of low pressure is often found from Central Morocco, extending northward into Southern Spain during this timeframe. This trough can dissipate when any frontal boundaries move southeastward toward Gibraltar. Approaching Gibraltar, easterly Levante winds, caused when higher surface pressures across the Iberian Peninsula and Western Mediterranean interact with lower pressures due to a trough over Morocco, occur on a semi-regular basis. These can often reach gale force, and produces large, short period seas in Gibraltar Strait, which can last for two to three days.
In the Mediterranean, Poniente winds are strong westerly wind surges that occur in the wake of frontal passages or when a cyclonic circulation extends southward from the Bay of Biscay to Gibraltar. These too can produce gale force conditions in Gibraltar Strait and large, short period seas. These can also last up to two to three days before easing.
Tropical systems are not yet a significant concern, though pre-season tropical development is not completely ruled out. The official commencement of the North Atlantic Tropical Season is not until June 1 to November 30. However, 17 systems have formed in the past 30 years in March through May in the Atlantic Basin, though, none have strengthened into hurricanes. So this averages to near one relatively weaker system every other year. Four of these originated in the Northwest Caribbean Sea, with the Eastern Caribbean remaining unthreatened.
Routing to the U.S. East Coast: From the Northeast Caribbean, we find it increasingly achievable to find wind for direct routing through western Atlantic waters this time of year, via west of Bermuda to the East Coast. Finding a window will depend on the placement of the subtropical ridge in the central Atlantic.
Commonly, the Northeastern Caribbean will reside within the southern periphery of the ridge, which will result in easterly trade winds at favorable sailing angles at beam to broad reaches for at least the first few days of the trip. Keep in mind, though, as the axis of the ridge is approached farther north, there may be a period of motoring necessary as winds within the ridge axis are extremely light. Then, on the northern side of the ridge axis, winds mostly begin to switch more west-southwesterly while remaining at beam to broad reaching angles north of about 30N. Keeping a direct course passing west of Bermuda will help hold these favorable sailing conditions.
This final portion would have to be monitored for gales and fronts across the northern Atlantic, although the frequency and strength of any passages tend to be less than in winter. Still, winds and seas will build modestly and for this reason, you should consider an alternative option, to bail in Bermuda and delay for a better window to finish the voyage. With either option, watch the Gulf Stream crossing as well, along with potential eddies north and west of Bermuda. Slight diversions from direct routing may be needed to avoid pockets of adverse conditions associated with these eddies, as well as providing specific waypoints to minimize any impacts of a Gulf Stream crossing depending on its placement at this time.
Routing Trans-Atlantic to the Mediterranean: The best wind for sailing across the Atlantic is found on the northern periphery of the subtropical high-pressure ridge in the central Atlantic. With this, following westerly winds means running a broad reach angle of sail for most of the voyage, though getting there first will often require a northern “dog-leg” route.
This best recommended route will generally follow a rhumb line to near 35N/60W, rhumb line to abeam south of Ponta Delgada, then rhumb line to Gibraltar. While routing north to the first recommended waypoint, on the western periphery of the ridge, easterly trades at near beam-reach angles will be experienced. This route transits slightly east of Bermuda, offering bailout opportunities if necessary to top off on fuel, or to delay for better weather in the event of any particularly stronger frontal passages or cut-off lows/gales.
Once the vessel reaches the 35N parallel, you will most often find yourself along the northern periphery of the ridge, with moderately strong ridging in place, generating more favorable westerly winds as you transit eastward thereafter. This next portion of the route to pass south of the Azores also provides another bailout option in the event of a less favorable pattern developing. This would be due to any particularly stronger or southward drifting cut-offs in the Central Atlantic to as far east as between the Azores and the Canaries. With this, larger (but longer period) northwesterly swell propagates southeastward toward the vessel, while also breaking down ridging, the source for favorable winds. Thus, this can impact your route if too uncomfortable or untenable for sailing and may force a period of motoring, a bailout, or more eastward to even east-southeastward routing to remain safely south.
The final feature to watch for will be any enhanced Levante or Poniente winds in Gibraltar Straits. A stoppage in Cadiz may be required if these were particularly strong or prolonged.
We maintain this northern route to be the best relative option for sailing conditions across the Atlantic. This is certainly recommended over any farther southern or even direct route. Within the axis of the ridge, sinking air and little to no pressure gradient impedes any development sailable winds. Whereas farther south in the southern periphery of the ridge, enhanced head conditions of east-northeasterly trades will significantly slow or halt any progress eastward as tacking proves quite difficult over a long distance.
Jumping from the Caribbean in spring can certainly throw some challenges sailors’ way. However, with adequate knowledge of the pattern and proper routing strategies in place, you can surely set yourself up for success to enjoy the most safe, efficient, and even comfortable sails over the next few months to your summer stays.
Kyle Petroziello is a senior meteorologist with WRI/Weather Routing Inc. (www.wriwx.com)
