Wind Near Coast

[Franklin]

From my days in high school, I remember them telling us that the wind during the day always blows onto the beach and at night it always blows off the beach because of the difference in the time it takes for Land to heat up and cool off compared to water. Assuming I got that right, how close would one have to be to shore to be able to count on the wind going in those directions?Note: They said it was a circular process...on the beach it would go one direction, but just a bit up in the air it would be traveling the opposite direction.

 

[Bill O'Donovan]

Right close

As long as there's no windbreak such as from those pesky trees that environmentalists keep hugging, you should get a good breeze.

 

[John Richard]

Transition zone

Franklin,I live in So. Calif. and am quite familiar with on and off shore wind conditions. Expect the change sometime around sunset. There is a zone where the on and off shore conditions meet, called the transition zone; you don't want to get caught here. As a rule of thumb in Calif, this can be expected from 5 to 10 nm off shore. If the water temperature is warmer than the land, especially if the difference is around 10 degrees, then expect an off-shore flow. A good way to get water temps is to visit this site: http://www.ndbc.noaa.gov/. This shows buoys in your area which will give a very accruate reading. Some buoys will also provide barometric, wind and other sea state conditions.The general rule of thumb for these conditions is: 0600 to 1000--transition0900 to 2000--off-shore1900 to 2300--transition2200 to 0700--on-shoreHere's a link that graphically shows what I am talking about. Sorry, but it is set for my area. http://www.nawcwpns.navy.mil/~weather/mugu/mesodata/analysis.html.Also, the prevailing wind will be stronger below a point and will accelerate down to the coast through a canyon. Look for rivers that empty to the sea and expect an increased land flow from them. If you have hills adjacent to the shoreline, then the wind will be less. Of course, in TX, you don't have much of that.Hope this helps,John Richards/v Jack's Place

 

[Franklin]

Sailing

So if the wind in the gulf is blowing west a few NM off shore between Houston and Florida, I can head close to shore to get a North or South wind, correct? I'm trying to avoid tacking back and forth on my way to NO from Houston.

 

[John Richard]

Franklin

Franklin,Without knowing your particular cruising grounds, all I can cite is theory. General theory says you need to pay attention to pressure gradients. If you are starting in New Orleans, find an inland place around there which has temperature and pressure that is different from someplace on the water. I'm basing this on the idea that coastal towns are cooler than those inland. Then, go to the prevailing wind of these and get two more. In your case, figuring that Texas runs north-south and the prevailing winds come from the west, then go to the west of the first two locations you have selected. What you do is to look at the gradients between them and see how the flow of air will move. Remember, the winds will move from a high to a low pressure system. Do this exercise three to four days before your departure date to get a pattern. The idea is that as the ground temperature cools off and becomes lower than the water temperature, then you can start to look for an off-shore flow of air. This flow isn't going to be much, but it will be better than what you would expect way off in a transition zone. John Richard