page_title: Tropical cyclone track forecasting
section_title: Single station forecasting of a tropical cyclone passage
hierarchical_section_title: Tropical cyclone track forecasting / Single station forecasting of a tropical cyclone passage
caption_attribution_description: English: The eyewall of a tropical cyclone, taken from a P-3.
context_page_description: Tropical cyclone track forecasting involves predicting where a tropical cyclone is going to track over the next five days, every 6 to 12 hours. The history of tropical cyclone track forecasting has evolved from a single-station approach to a comprehensive approach which uses a variety of meteorological tools and methods to make predictions. The weather of a particular location can show signs of the approaching tropical cyclone, such as increasing swell, increasing cloudiness, falling barometric pressure, increasing tides, squalls, and heavy rainfall.
  The forces that affect tropical cyclone steering are the higher-latitude westerlies, the subtropical ridge, and the beta effect caused by changes of the coriolis force within fluids such as the atmosphere. Accurate track predictions depend on determining the position and strength of high- and low-pressure areas, and predicting how those areas will migrate during the life of a tropical system. Computer forecast models are used to help determine this motion as far out as five to seven days in the future.
context_section_description: About four days in advance of a typical tropical cyclone, an ocean  of 1 metre (3.3 ft) in height will roll in about every 10 seconds, moving towards the coast from the direction of the tropical cyclone's location.  The ocean swell will slowly increase in height and frequency the closer a tropical cyclone gets to land.  Two days in advance of the center's passage, winds go calm as the tropical cyclone interrupts the environmental wind flow.  Within 36 hours of the center passage, the pressure begins to fall and a veil of white cirrus clouds approaches from the cyclone's direction.  Within 24 hours of the closest approach to the center, low clouds begin to move in, also known as the bar of a tropical cyclone, as the barometric pressure begins to fall more rapidly and the winds begin to increase.  Within 18 hours of the center's approach, squally weather is common, with sudden increases in wind accompanied by rain showers or thunderstorms.  Winds increase within 12 hours of the center's approach, occasionally reaching hurricane force.  The ocean's surface becomes whipped with foam.  Small items begin flying in the wind.  Within 6 hours of the center's arrival, rain becomes continuous and the storm surge begins to come inland.  Within an hour of the center, the rain becomes very heavy and the highest winds within the tropical cyclone are experienced.  When the center arrives with a strong tropical cyclone, weather conditions improve and the sun becomes visible as the eye moves overhead.  At this point, the pressure ceases to drop as the lowest pressure within the storm's center is reached.  This is also when the peak depth of the storm surge occurs.  Once the system departs, winds reverse and, along with the rain, suddenly increase.  The storm surge retreats as the pressure suddenly rises in the wake of its center.  One day after the center's passage, the low overcast is replaced with a higher overcast, and the rain becomes intermittent.  By 36 hours after the center's passage, the high overcast breaks and the pressure begins to level off.
caption: Picture of the sky within the eye of a tropical cyclone
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