Thursday, June 10, 2010

Local Knowledge

I wish there was more. With predominantly gradient winds, Chicago does not exhibit what I consider ‘formula’ type sailing conditions. This is generally not the kind of place where you go only left/right in a given condition. As mentioned in some of our preliminary event information, we anticipate three different conditions.

ESE 5-11kts: this is our thermal breeze that typically establishes itself when there is a high pressure system stalled over the region. There is often little wind near shore, but in the sailing area the breeze is usually well established with calm seas. Locals feel that there is often more breeze ‘out in the lake’ (left side of the course) from this direction. Shifts typically develop slowly and in the range of 5 to 15 degrees with subtle changes in pressure.

NNE 10-20kts: cool ‘clipper systems’ of high pressure bring what is known as a three day northeaster to Lake Michigan. Air temperatures drop into the low 70s during the daytime and the strong winds on the leading edge of the high kick up great sailing conditions. Waves from 2 to 6 feet are typical. The breeze is strongest on day one of the system and usually moderates over the next two days. This can make for a light and lumpy third day. The direction is typically very stable with 5 to 10 degree shifts.

SW 12-25kts: hot, humid, and blustery breezes arrive with low pressure systems. This offshore breeze is both shifty and puffy. We will be sailing well offshore in this direction if possible to allow the wind to stabilize after it passes through the city. Velocity can vary by 5kts or more in the puffs and shifts are usually in the 10 to 25 degree range. There can be some skew to the racecourse in this condition as the breeze may favor a particular lane through the city’s buildings.

No comments:

Post a Comment