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Marine Warning or "BMS"

World Meteorological Organization (WMO) header : WTIO20, 22, 24, 26 FMEE

The Marine Warning provides information related to a tropical, subtropical or extratropical system to the marine users. This warning indicates the system’s intensity, motion and number, the latitude and longitude coordinates of the storm’s centre, and a description of the related disturbed weather, winds and sea areas. Then follow track and intensity forecasts for 12 and 24 hours ranges from the current synoptic time, and comments.

These Marine Warnings are issued whenever a tropical or subtropical or extratropical (from tropical origin) cyclone is present on the SouthWest Indian Ocean every 6 hours, at 0000, 0600, 1200, 1800 UTC. For weak systems these marine warnings may be issued on an irregular framework.

Example

WTIO22 FMEE 130009
SECURITE
STORM WARNING FOR METAREA VII AND METAREA VIII (S)
ISSUED BY METEO-FRANCE/TROPICAL CYCLONE CENTRE/LA REUNION 13/04/2006 AT 0000 UTC.
WARNING NUMBER: 010/12 (SOUTH-WEST INDIAN OCEAN)

10 MINUTES AVERAGE WIND SPEED IN KNOTS (KT)
(WIND GUSTS AT SEA MAY BE ABOUT 40% STRONGER THAN THE AVERAGED WIND).
MINIMUM SEA LEVEL PRESSURE IN HECTOPASCALS (HPA)
(INDICATIVE FIGURE).

STORM WARNING
BEGINNING OF VALIDITY: TUESDAY 13/04/2006 AT 0000 UTC.

PHENOMENON: SEVERE TROPICAL STORM 12 (DUMMY) 980 HPA
POSITION: WITHIN 20 NM RADIUS OF POINT 13.0S / 55.4E
(THIRTEEN DECIMAL ZERO DEGREES SOUTH AND FIFTY FIVE DECIMAL FOUR DEGREES EAST) AT 0000 UTC
MOVEMENT: WEST-SOUTH-WEST 6 KT

THREAT AREAS:
SQUALLY WEATHER EXISTS WITHIN 180 NM RADIUS FROM THE CENTRE, EXTENDING UP
TO 250 NM FROM THE CENTRE IN THE WESTERN SEMI-CIRCLE.

STORM FORCE WINDS 50/55 KT AND HIGH TO VERY ROUGH SEAS WITHIN 20 NM RADIUS OF THE CENTRE.
GALE FORCE WINDS 35/45 KT AND VERY ROUGH TO HIGH SEAS WITHIN 60 NM RADIUS OF THE CENTRE
NEAR GALE FORCE WINDS 30 KT AND ROUGH TO VERY ROUGH SEAS WITHIN 120 NM
RADIUS OF THE CENTRE EXTENDING UP TO 240 NM IN THE SOUTHERN SEMI-CIRCLE
STRONG GUSTS UNDER SQUALLS.

FORECAST POSITION AND INTENSITY:
12H, VALID 2006/04/13 AT 12 UTC:
13.1S / 54.5E, MAX WIND = 60 KT, SEVERE TROP. STORM.
24H, VALID 2006/04/14 AT 00 UTC:
13.6S / 53.6E, MAX WIND = 65 KT, TROPICAL CYCLONE.

OTHER INFORMATION:
THE SYSTEM KEEPS ON REGULARLY INTENSIFYING WITHIN A FAVORABLE ENVIRONMENT, AND AN EYE IS NOW VISIBLE ON THE LAST SATELLITE IMAGERY.
NEAR GALE FORCE WINDS EXTENSION IS MORE IMPORTANT IN THE SOUTHERN PART
DUE TO THE GRADIENT WITH THE SUBTROPICAL HIGH PRESSURES. THIS EXTENSION
IS MEASURED THANKS TO RECENT SATELLITE DATA.
THE SYSTEM IS EXPECTED TO KEEP ON TRACKING GLOBALLY WESTWARDS ON THE
NORTHERN EDGE OF THE HIGH PRESSURES OVER THE NEXT 12 HOURS INTENSIFYING
GRADUALLY AND THEN TO CURVE SOUTHWESTWARDS TOWARDS A TROUGH TRANSITING IN THE SOUTH.

How to read

The Marine Warning is generally composed of several easily identified sections. These sections in the warning will always occur in the order specified here. Click on each section title and read the brief description of the section contents in the example.

1. Identification
2. Warning type and validity
3. Current System and minimum central pressure
4. Position and Motion
5. Threat areas
6. Wind and sea
7. Forecasts
8. Other information

STORM WARNING
BEGINNING OF VALIDITY: TUESDAY 13/04/2006 AT 0000 UTC.

Section: Warning type and validity

This section gives the current warning type (warning; near gale, gale, storm, or hurricane warning) and the date of the beginning of validity (DD/MM/YYYY).

PHENOMENON: SEVERE TROPICAL STORM 12 (DUMMY) 980 HPA

Section: Current System and minimum central pressure

This section gives the system’s type (tropical disturbance, tropical depression, moderate tropical storm, severe tropical storm, tropical cyclone, intense tropical cyclone, very intense tropical cyclone, subtropical depression, etc ...) and number followed by the name in brackets (if existing - a system is usually named when it becomes moderate tropical storm) and the minimum central pressure in hPa.

POSITION: WITHIN 20 NM RADIUS OF POINT 13.0S / 55.4E
(THIRTEEN DECIMAL ZERO DEGREES SOUTH AND FIFTY FIVE DECIMAL FOUR DEGREES EAST) AT 0000 UTC
MOVEMENT: WEST-SOUTH-WEST 6 KT

Section: Position and Current motion

This section indicates the location of the system’s centre in latitude/longitude - in degrees and tenth of degrees, and its time of validity. Before comes an indication about the uncertainty of the position, in nautical miles (optional). Then the current motion of the system is detailed, in knots or nautical miles per hour (1kt = 1nm = 1.852 km/h), with the direction expressed in terms of 16 compass directions (north, north-northeast, east-northeast, east ...).

THREAT AREAS:
SQUALLY WEATHER EXISTS WITHIN 180 NM RADIUS FROM THE CENTER, EXTENDING UP TO 250 NM FROM THE CENTRE IN THE WESTERN SEMI-CIRCLE.

Section: Threat areas

This section details in nautical miles (1 nm = 1852 m) from the centre, the areas threatened by thundery and stormy weather conditions associated to the system.

STORM FORCE WINDS 50/55 KT AND HIGH TO VERY ROUGH SEAS WITHIN 20 NM RADIUS OF THE CENTRE.
GALE FORCE WINDS 35/45 KT AND VERY ROUGH TO HIGH SEAS WITHIN 60 NM RADIUS OF THE CENTRE
NEAR GALE FORCE WINDS 30 KT AND ROUGH TO VERY ROUGH SEAS WITHIN 120 NM
RADIUS OF THE CENTRE EXTENDING UP TO 240 NM IN THE SOUTHERN SEMI-CIRCLE
STRONG GUSTS UNDER SQUALLS.

Section: Winds and sea state

This section details the main characteristics of the wind field and related sea state associated to the tropical system with the corresponding radial extents, in nautical miles from the centre, of the different winds categories (following typical threshold wind values like: near gale force winds (28-33 kt), gale force winds (34-47 kt) storm force winds (48-63 kt), and hurricane force winds (above 63 knots). The wind and wave radii may appear discriminated by sectors or quadrants surrounding the storm’s centre.

FORECAST POSITION AND INTENSITY:
12H, VALID 2006/04/13 AT 12 UTC:
13.1S / 54.5E, MAX WIND = 60 KT, SEVERE TROP. STORM.
24H, VALID 2006/04/14 AT 00 UTC:
13.6S / 53.6E, MAX WIND = 65 KT, TROPICAL CYCLONE.

Section: Forecasts

This section provides the 12 and 24-hour forecasts of the centre’s position and system’s intensity.
Position appears in latitude/longitude and intensity as 10-minute average maximum winds associated to the corresponding type.

OTHER INFORMATION:
THE SYSTEM KEEPS ON REGULARLY INTENSIFYING WITHIN A FAVORABLE ENVIRONMENT, AND AN EYE IS NOW VISIBLE ON THE LAST SATELLITE IMAGERY.
NEAR GALE FORCE WINDS EXTENSION IS MORE IMPORTANT IN THE SOUTHERN PART
DUE TO THE GRADIENT WITH THE SUBTROPICAL HIGH PRESSURES. THIS EXTENSION
IS ASSESSED THANKS TO RECENT SATELLITE DATA.
DUMY IS EXPECTED TO KEEP ON TRACKING GLOBALLY WESTWARDS ON THE
NORTHERN EDGE OF THE HIGH PRESSURES OVER THE NEXT 12 HOURS INTENSIFYING
GRADUALLY AND THEN TO CURVE SOUTHWESTWARDS TOWARDS A TROUGH TRANSITING TO THE SOUTH.

Section: Other information

This part gives any additional information useful to enlighten data provided within the warning’s body.

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