Volvo Ocean Race
Friday 24 April 2009, 01:00 GMT
With high pressure building in from the south, clear skies and unseasonably warm temperatures will fill over the east coast, making for a great weekend in Boston. Unfortunately this same high will slow the fleet, causing upwind sailing for the sprint to the finish.
As of Friday morning, the winds across the fleet were light, with everyone on the north side of Thursday's cold front. Through the morning the winds will redevelop quickly, likely filling out of the WSW, then veering right towards NW'ly with the pressure gradient around the northeastern periphery of the large high. The winds will fill nicely, with speeds likely in the high teens, but the progress will be slow as the teams will be forced to sail upwind.
This same high will drive the conditions through the weekend, sliding slowly east as it spreads out along the entire eastern seaboard. As a result the winds will ease briefly on Saturday morning backing towards W'ly around the top of the high, before filling as SW'ly along the immediate coast.
The tactical decisions made over the next two days will be critical, with the fleet not only considering the tightening angle of the winds, but also the increasing current of the Gulf Stream. The current in the Gulf Stream can be quite strong, generally running northeast at several knots. However, with meanders and eddies to consider a team could easily find themselves being set away from the finish. Eddies to the south of the stream generally rotate counter clockwise with a cold water center, while eddies north of the stream generally have a warm water center and rotate clockwise. As you can see in the attached image a small course change could make a big difference in terms of favorable versus unfavorable current. It is unlikely the fleet will be able to take advantage of the Gulf Stream for long, however, they will see current, both favorable and unfavorable from eddies for the next 3 days.
While the expected arrival is still on track for Sunday evening, it will not be a smooth road. Luckily the unusually warm weather should last into the beginning of next week, so the sailors will get to enjoy their time off.
Jennifer Lilly, Race Meteorologist