St. Petersburg Times

Few people are affected more by weather than the mariner. An unexpected change in winds, seas or visibility can reduce the efficiency of marine operations and threaten the safety of a vessel and its crew. The National Weather Service (NWS), a part of the National Oceanic and Atmospheric Administration (NOAA), provides marine weather warnings and forecasts to serve all mariners who use the waters for livelihood or recreation. Local weather patterns are fairly predictable. In the fall, winter and spring, cold fronts roll in from the north anywhere from several days to more than a week apart. During the summer, storms can form over the Gulf of Mexico or the Florida Peninsula, depending on the location of the Atlantic Ridge or Bermuda High.
1. The Loop Current
Warm water from the Yucatan Current (fed by the Caribbean, Guiana and North Equatorial currents) flows northward through the Yucatan Channel and into the Gulf of Mexico. The current can travel as far north as the Mississippi River Delta before “looping” south and feeding into the Florida Current.

Web site: www.oceancurrents.

2. The Florida Current
This warm water then flows into the Straits of Florida and runs along the Keys before hooking northward again. From space, the current looks like a river within the ocean. It can be 10 degrees warmer than surrounding waters.
3. The Gulf Stream
This major ocean current travels north along the Eastern Seaboard before turning northeast at Cape Hatteras, N.C. Mariners have long used the Gulf Stream to help carry goods north and ultimately east to European markets. The path of the Gulf Stream can vary day to day. Since the Gulf Stream water is much clearer than surrounding waters, it appears deep blue from outer space. Scientists use satellite imagery to help pinpoint the Gulf Stream’s location.
Ocean currents
Ocean currents, such as the Loop, Florida and Gulf Stream, play a significant role in world weather patterns. Since the waters of the Gulf Stream originate in the sunny Caribbean, the water is warm. In the winter, the water off Cape Hatteras, N.C. is actually warmer than the air temperature. The prevailing winds blow east across the warm water, which is why England, Ireland and Norway have warmer climates than other countries at the same latitude.

Buoys in the gulf
Marine observations
Buoys and land sites provide measurements of wind temperature, pressure and at some locations wave height.
Web site:

Wave height
Mariners find information on wave height particularly useful. The National Weather Service uses the term “significant wave height” in its forecast. This is defined as the average of the highest one-third of the waves. The chances of encountering such a wave is one in 10. But one out of every 1,000 waves will be double the significant wave height. This could be where the term “rogue wave” originated. “Rogue” waves form when wave trains of different speeds and directions meet, forming en extreme wave.

Mariners can obtain the latest coastal and offshore weather observations through a telephone service.
Phone: (228) 688-1948
Web site:

Times graphic by MICHAEL GUILLEN • text by TERRY TOMALIN
page 1page 2

Sources: Charlie Paxton and Ernie Jillson, National Oceanic and Atmospheric Administration, National Weather Service