256 seamanship secrets
Q Puff y cumulus clouds that dot the sky signal fair weather. If the cumuli
mass together and develop into a rising vertical column of nimbostratus
clouds, expect a thunderstorm.
Q Th e approach of a warm front is heralded by high clouds: cirrus fi rst,
followed by cirrostratus, altostratus, and fi nally nimbostratus. Your fi rst
sign will be cirrus that lower and thicken into cirrostratus (mare’s tales).
Q Cold fronts give much less warning of their approach. When cumulus
clouds band together to develop into towering cumulonimbus, stand by
for heavy weather!Weather Information Resources for Mariners
For inland waters, you might use Internet marine weather sites (listed below), or
marine weather forecasts (see below). For distance cruising, start with a general
overview from Coast Pilots (see Chapter 1), Cruising Guides, or Reeds Almanac. Next,
use resources from the Internet, along with off shore radio broadcasts (see below).
In either case, include your own observations to revise forecast predictions.
U.S. Coastal Marine Weather Forecasts
NOAA Weather Service broadcasts 24 hours each day on VHF-FM radio. Most
modern FM radios have a WX1 and WX2 button. Push one or the other and
select the clearest channel. Radios not so equipped should try one of the following
frequencies: 162.400, 162.425, 162.450, 162.475, 162.500, 162.525 or 162.550 FM.
Coverage includes the coastline of the United States, Great Lakes, Hawaii, and
the populated coast of Alaska off shore to 25 nautical miles.
U.S. and Caribbean Offshore Forecasts
For a graphical point-and-click forecast extending several hundred miles off shore,
click on: http://www.weather.gov/om/marine/zone/wrdoff mz.htm
In addition, mariners can download weather briefi ng packages (these include
forecasts extending out 96 hours, and include surface analysis charts, wind and
wave charts, as well as upper-air charts) from the National Weather Service
website in the radiofax section (for example, you can get one for Boston, MA, at
http://weather.noaa.gov/fax/marine.shtml)..)
High Seas Offshore Forecasts
Access the NOAA marine weather site at http://www.nws.noaa.gov/om/marine/
home.htm. Scroll to the lower half of the page for links that show upper side
band (USB) frequencies for high seas offshore marine weather forecasts. (This
is the home page of the NOAA site—here you will find many resources.)