Tropical Revolving Storm Flashcards
(2 cards)
State the on board meteorological and oceanographical indicators of a possible TRS.
) Swell
In open waters, with no intervening land, a swell generated by the high seas within a Tropical Revolving
Storm may be the earliest warning of a storm.
The swell approaches from the direction of the storm.
Atmospheric pressure.
In the tropics the diurnal variation of atmospheric pressure is marked and a normal feature.
Falling pressure in the area affected by a Tropical Revolving Storm initially damps the diurnal variation,
and the disappearance of this feature is an early warning sign of Tropical Revolving Storm development.
The atmospheric pressure in the tropics varies little from the seasonal average.
A decrease of 3 hPa below the seasonal average for the area indicates the probable development of a
Tropical Revolving Storm in the vicinity.
A decrease of 5 hPa below the seasonal average for the area indicates the presence of a Tropical
Revolving Storm, probably within 200 NM.
Decreasing atmospheric pressure indicates the approach of a Tropical Revolving Storm.
Wind
Wind direction and speed is generally fairly constant in the tropics.
Increasing wind speed and variation from the normal direction for the area and season are indications of
the approach of a Tropical Revolving Storm.
Clouds
Vivid coloring of the sky at sunrise and sunset may be a precursor of a Tropical Revolving Storm.
Cirrus clouds increasing in density may be visible 300 to 600 NM from the storm and are followed by
lower Cumulonimbus clouds increasing in coverage as it approaches.
Visibility
Exceptionally good visibility frequently exists in the vicinity of a Tropical Revolving Storm.
Radar
Radar is capable of detecting the precipitation of a Tropical Revolving Storm.
The range is limited, and other signs will probably be manifest before the storm is within radar range.
The rainfall pattern indicated on Radar may be useful if close to the eye to avoid the most severe
conditions
The ship comes under the influence of the TRS and the Master needs to take action to safeguard
the ship and personnel.
The following meteorological conditions are noted:
Wind NE Force 6.
Pressure falling slowly.
Swell from SSE.
The US National Hurricane Centre predict that the TRS will continue on its present course 300°T and
increase speed to 9.0 knots.
The ship is not navigationally restricted.
(i) Outline the relative position of the ship in relation to the TRS. (8)
(ii) Outline how a prudent Master should maneuvers the ship in light of the predicted path of the TRS
and the ship’s relative position.
i)
Wind NE Force 6.
Buys Ballot, NE, Right, 90° + AoI 2 points.
TRS is SSE of the vessel.
Pressure falling slowly.
In advance of the Trough Line.
Swell from SSE.
Confirms direction from wind.
Vessel is NNW of TRS
Approximately 200NM away
In advance of the Trough Line
TRS tracking 300°.
Vessel is close to the Path.
ETA 22 hours.
ii) Northern Hemisphere, on the Path.
Steer a course with the wind on the starboard quarter.
Proceed at maximum practicable speed.
Alter course to maintain the relative wind direction as the wind backs.
All parameters must be monitored to assess the movement of the storm, and the action taken modified
accordingly.
