Warning Signals for Sea and River Ports

Knowledge about the warning signals is significant for general mass to prepare for the storms and protect lives and property.

By
Tanvir Siddiqui
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Bangladesh is one of the most natural disaster prone countries in the world. Most of these disasters are meteorological and hydrological in nature such as Cyclone and associated Storm Surge. Knowledge about the warning signals is therefore significant for general mass to prepare for the storms and protect lives and property.
The following is the classification of the cyclone according to the intensity and velocity of the wind.
(a) Depression : Wind speed 31 miles/hr or 50 km/hr.
(b) Deep depression : Wind speed 32-38 miles/hr or 51-61 km/hr.
(c) Cyclone : Wind speed 39-54 miles/hr or 62-88 km/hr.
(d) Severe Cyclone : Wind speed 55-73 miles/hr or 89-117 km/hr.
(e) Cyclone with a hurricane : Wind speed 74 miles/hr or 118 km/hr or more.
Warning Signals for Sea and River Ports:
For seaports the following 11 (Eleven) kinds of cyclone warning signals are used:
Signals
Meanings
Distant Cautionary Signal No. I
There is a region of squally weather (wind speed of 61 kms/hour) in the distant sea where a storm may form.
Distant Warning Signal No. II
A storm (wind speed of 62-88 kms/hour) has formed in the distant deep sea. Ships may fall into danger if they leave harbour,
Local Cautionary Signal No.III
The port is threatened by squally weather (wind speed of 40-50 kms/hour).
Local Warning Signal No.IV
The port is threatened by a storm (wind speed of 51-61 kms/hour) but it doesn’t appear that the danger is as yet sufficiently great to justify extreme precautionary measures.
Danger Signal No. V
The port will experience severe weather from a storm of slight or moderate intensity (wind speed of 62-88 kms/hour) that is expected to cross the coast to the south of Chittagong port or Cox’s Bazar port and to the east of Mongla port.
Danger Signal No. VI
The port will experience severe weather from a storm of slight or moderate intensity (wind speed of 62-88 kms/hour) that is expected to cross the coast to the north of the port of Chittagong or Cox’s Bazar and to the west of the port of Mongla.
Danger Signal No. VII
The port will experience severe weather from a storm of light or moderate intensity (wind speed of 62-88 kms/hour) that is expected to cross over or near the port
Great Danger Signal No. VIII
The port will experience severe weather from a storm of great intensity (wind speed of 89 kms/hour or more) that is expected to cross the coast to the south of the port of Chittagong or Cox’s Bazar and to the east of the port of Mongal.
Great Danger Signal No. IX
The port will experience severe weather from a storm of great intensity (wind speed of 89 kms/hour or more) that is expected to cross the coast to the north of the port of Chittagong or Cox’s Bazar and to the west of the port of Mongla.
Great Danger Signal No. X
The port will experience severe weather from a storm of great intensity (wind speed of 89 kms/hour or more) that is expected to cross over or near the port.
Failure of Communication No. XI
Communications with the Storm Warning Centre have broken down and local officers consider that a devastating cyclone is following.
The following 4 (four) types of signals are used for inland River Ports:
Signals
Meanings
Cautionary Signal No. I
The area is threatened by squally winds (wind speed of 60 kms/hour) of transient nature. This signal is also hoisted during nor’westers.
Warning Signal No. II
A storm (wind speed of 61 kms/hour) or a nor’wester (wind speed 61 kms/hour or more) is likely to strike the area (Vessels of 65 feet and under in length are to seek shelter immediately.
Danger Signal No. III
A storm (wind speed of 62-88 kms/hour or more) is likely to strike the area soon (all vessels will seek shelter immediately).
Great Danger Signal No. IV
A violent storm (wind speed of 89 kms/hour or more) will strike the area soon (all Vessels will take shelter immediately).
Moreover, the below-mentioned definitions are also useful to understand the signals:
1. Cautionary: There is a region of squally weather in which a storm may be formed.
2. Warning: A storm has formed.
3. Danger: A storm will soon strike the area.
4. Great Danger: A violent storm will soon strike the area.

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