 |
Understanding the Shipping Forecast
The Shipping Forecast uses a standard and abbreviated format to pass a lot of information in a short period of time - by knowing what's being said and in what order (always the same) it's possible to gain an understanding of the conditions, even in poor reception areas if listening to the forecast on marine VHF.
The Coastguard broadcasts Marine Safety Information (MSI) Inshore & Area Forecasts every 4 hours on marine VHF - click here for broadcast times. Broadcast schedules are also included in the UKSKGB "Easy Reference" .pdf's for Scotland - Western England & Wales - Eastern England.
Other sources of weather information are linked from the Almanac / Weather page.
As well as marine VHF, weather bulletins for shipping are broadcast daily on BBC Radio 4 at the following times: 0048 and 0535 (long wave and FM), 1200 and 1755 (normally long wave only). The bulletins consist of a gale warning summary, general synopsis, sea-area forecasts and coastal station reports. In addition, gale warnings are broadcast at the first available programme break after receipt. If this does not coincide with a news bulletin, the warning will be repeated after the next news bulletin.
| Example Area Forecast | Explanation |
| THE SHIPPING FORECAST ISSUED BY THE MET OFFICE, ON BEHALF OF THE MARITIME AND COASTGUARD AGENCY, AT 1725 ON SATURDAY 02 JULY 2005 | Time & date of the forecast. |
| THERE ARE WARNINGS OF GALES IN SHANNON ROCKALL MALIN HEBRIDES BAILEY FAIR ISLE FAEROES AND SOUTHEAST ICELAND | Any Gale Warnings are issued first, with details of the Sea Areas to which they apply. See the Sea Areas chart below. |
| THE GENERAL SYNOPSIS AT 1300 LOW JUST WEST OF ROCKALL 987 EXPECTED BAILEY 983 BY 1300 TOMORROW |
This is a general overview - at 1300 there is a low pressure area to the west of Rockall - with a barometric pressure of 987. It's expected to move NE to Bailey with a barometric pressure of 983 by 1300 Sunday 3 July. (Low pressure tends to produce unsettle, poor weather - as I write this, it is!). The difference between the pressures is of interest - in this case, the relative similarity tells us that the conditions won't change much. |
| THE AREA FORECASTS FOR THE NEXT 24 HOURS | (Area forecasts run clockwise.) - See the Sea Areas chart below. This is the detail of the forecast relevant to the areas mentioned in the forecast. |
| VIKING NORTH UTSIRE SOUTH UTSIRE SOUTHEAST 4 OR 5 INCREASING 6 OR 7 VEERING SOUTH 4 OR 5 LATER. OCCASIONAL RAIN. GOOD WITH FOG PATCHES BECOMING MODERATE OR POOR |
For the sea areas Viking, North Utsire and South Utsire. These are located NE of UK. Wind from the Southeast, windspeed force 4 or 5, increasing to force 6 or 7, veering / changing in a clockwise direction to the South, force 4 or 5 but not within the next 12 hours. Occasional rain. Visibility will be good / more than 5 nautical miles, but with patches of fog and becoming moderate / between 2 and 5 nautical miles or poor / between 1,000 metres and 2 nautical miles. |
|
Term used |
Definition |
|
Gale Warnings |
|
Gale |
Winds of at least Beaufort Scale force
8 (34-40 knots) or gusts reaching 43-51 knots |
Severe gale |
Winds of force 9 (41-47 knots) or gusts reaching 52-60 knots |
Storm |
Winds of force 10 (48-55 knots) or gusts reaching 61-68 knots |
Violent storm |
Winds of force 11 (56-63 knots) or gusts of 69 knots or more |
Hurricane force |
Winds of force 12 (64 knots or more) Note: The term used is 'hurricane force'; the term 'hurricane' on its own means a true tropical cyclone, not experienced in British waters. |
|
Timescales |
|
| Imminent |
Expected within six hours of time of issue |
| Soon |
Expected within six to 12 hours of time of issue |
| Later |
Expected more than 12 hours from time of issue |
| Visibility | |
| Fog | Visibility less than 1,000 metres |
| Poor | Visibility between 1,000 metres and 2 nautical miles |
| Moderate | Visibility between 2 and 5 nautical miles |
| Good | Visibility more than 5 nautical miles |
| Movement of pressure systems | |
| Slowly | Moving at less than 15 knots |
| Steadily | Moving at 15 to 25 knots |
| Rather Quickly | Moving at 25 to 35 knots |
| Rapidly | Moving at 35 to 45 knots |
| Very Rapidly | Moving at more than 45 knots |
| Pressure tendency in station reports | |
| Rising (or falling) slowly | Pressure change of 0.1 to 1.5 hPa in the preceding three hours |
| Rising (or falling) | Pressure change of 1.6 to 3.5 hPa in the preceding three hours |
| Rising (or falling) quickly | Pressure change of 3.6 to 6.0 hPa in the preceding three hours |
| Rising (or falling) v. rapidly | Pressure change of more than 6.0 hPa in the preceding three hours |
| Now rising (or falling) | Pressure has been falling (rising) or steady in the preceding three hours, but at the time of observation was definitely rising (falling) Note: For those more familiar with the millibar, 1 hPa = 1 mb |
| Wind |
|
|
Wind direction |
Indicates the direction from which the wind is blowing |
Becoming cyclonic |
Indicates that there will be considerable change in wind direction
across the path of a depression within the forecast area |
|
Veering |
The changing of the wind direction clockwise, e.g. SW to W |
Backing |
The changing of the wind in the opposite direction to veering (anticlockwise), e.g. SE to NE |
