weather and water wisdom 257
European Coastal and High Seas Forecasts
Coastal broadcasts are given by the Coastguard MRCC/MRSC stations via NAVTEX
(a nautical information station on upper side band radio). Forecasts on marine
VHF and medium frequency band radios provide coverage 200 to 300 miles
off shore. BBC Radio 4 supplements these broadcasts with an inshore weather
forecast and (off shore) shipping weather forecast.
Marine Weather Websites for Cruise Planning
http://www.buoyweather.com/
http://www.passageweather.com/
http://www.oceanweather.com/
How to Predict Wind Shift s in Low-Pressure Systems
In North America, most high-pressure systems move west to east and then progress
out over the Atlantic Ocean. Lows typically move west to east over the continent
but then bend northeasterly along the eastern seaboard toward the colder waters
of the North Atlantic. Fast-moving lows travel up to 500 miles per day. East Coast
sailors should keep a sharp watch on any low draped over the Mississippi Delta
region. Expect these systems to catch up to you within 48 hours, bringing reefi ng
breezes and rough seas.
DETERMINING A LOW-PRESSURE SYSTEM’S LOCATION
Dutch meteorologist Christoph Buys-Ballot devised a clever method for
finding the direction to the center of any low-pressure system. If on land, at
a dock, or anchored you can find this without using a compass.
- Stand with your back to the wind.
- Point your left arm straight from your side (in the Southern
Hemisphere, use your right arm). - Move your arm back 10 to 20 degrees. Now you’re aiming at the low-
pressure center.
If you are underway and making way, you’ll need to use a compass:
- Power vessels should turn to bring the wind astern.
- Sailing vessels should fall off to a run.
Glance at your steering compass and subtract 110 degrees (in the Southern
Hemisphere, add 110 degrees).
You are in the Northern Hemisphere and need to track the location of a nearby
low-pressure system. Fall off dead downwind and read your steering compass:
127 degrees magnetic.