Mariners Weather Log Vol. 53, No. 2, August 2009

The PMO’s Corner

This is the first in a regular series of articles we will be featuring in the Mariners Weather Log. We will be answering questions that you, the ship operators, are interested in. Topics will cover questions that you are asking the PMO’s during our visits or through e-mail. If you have a topic or question that you would like to see covered or think others else would benefit from, call or send your PMO an email or you can email VOS@noaa.gov and your question will be considered for an upcoming issue.

This issue’s question comes from 1st Officer Emil Listherby from the Adventure of the Seas. Emil asked “is there any minimum distance from land when the reports should be sent?”

The technical answer to this question can be found in the Observer Handbook #1 on page 1-2.

It States:

STANDARD WEATHER REPORTING SCHEDULE FOR SHIPS

The worldwide weather-reporting schedule for Voluntary Observing Ships is 4 times daily - at 0000, 0600, 1200, and 1800 UTC. These are the “main synoptic” times, when weather forecasts are prepared and, therefore, when data is needed most. Two of these times, 0000 and 1200 UTC, are most important - when the numerical weather prediction models are initialized with data and also when soundings are released from upper air stations all over the world. Reporting weather once every 3 hours when within 300 miles of a named tropical storm or hurricane is also standard practice worldwide. Storm (wind speed 48 knots or higher) or special reports for conditions not forecast, much worse than forecast, or for sudden weather changes) should be sent whenever conditions warrant.

3-HOURLY WEATHER REPORTING SCHEDULE

Vessels operating on the Great Lakes, and within 200 miles of the U.S. or Canadian coastlines (including the coasts of Alaska, Hawaii, and Gulf Coast States), are asked to transmit their observations once every three hours - at 0000, 0300, 0600, 0900, 1200, 1500, 1800, and 2100 UTC. This special schedule is maintained because of a data shortage from nearshore areas. All weather reports are voluntary — try to follow the recommended reporting schedule as best you can. Always give top priority to reports at the main synoptic hours (6-hour intervals). When shipboard routine permits, follow the 3-hour schedule from coastal waters.

What does this all mean? There are no hard and fast rules, only guidelines. Every weather observation your ship transmits (regardless of the method) will be used, no matter where your ship is located. During an open ocean voyage, your weather observation is used by various World Meteorological Organizations (WMO) and computer models to produce weather charts and forecast models. Additionally, when your ship reports near the U.S. Coast, at anchorage or pier-side, the local National Weather Service Forecast Offices use your observations to produce/verify local coastal forecasts and warnings. There can never be too many observation points.

Bottom line, we encourage all ships to send in as many weather observations as possible. Even when in port or at anchorage, your observations are used by the local Weather Forecast Office for local wind and seas warnings and also used to verify local near-shore forecasts and warnings. Obviously, when the bridge crew is busy, the safe operation of the ship is the priority. However, if available, we will gladly accept all weather observations no matter where your ship is operating or docked.