What is a Flash Flood, Flash Flood Watch and Flash Flood Warning?

You’ve heard the terms on the news or on announcements made on media: flash-flood warning for certain parishes, or flash flood watch. In Jamaica, these announcements are directives from the Office of Disaster Preparedness and Emergency Management (ODPEM), or the Meteorological Service of Jamaica. They are usually made in times when the country is undergoing intense weather, especially in the rain and hurricane season.

What do these terms mean?

Here are the official definitions for these terms:

Flash Flood: This is a flood event that occurs with little or no warning where water levels rise very quickly. Flash floods are the result of heavy rainfall or cloudburst over a relatively small drainage area. Flash floods carry highly destructive flood waves and are most common in mountainous areas or in steep places that have streams flowing though narrow canyons.

Flash Flood Watch: This means that a flash flood is possible in the area and citizens should be on the alert and be ready to take action if flooding is observed or a warning is given.

Flash Flood Warning: This means that flash flooding is imminent or has been reported. Residents in low-lying areas should be on the alert for fast-rising waters and get ready for immediate action. Motorists and pedestrians are advised not to attempt to cross flooded streets, roads, low bridges or fordings.

Where do most floods in Jamaica occur?

Areas most likely to be worst affected by flooding are:

  • Low-lying coastal areas
  • Areas near gully banks
  • Flood plains of major rivers
  • Lower sections of closed limestone valleys (e.g. Newmarket)
  • Areas vulnerable to landslides
  • Low-lying coastal towns and villages

Persons who live close to these areas are urged to be on the alert in case of a disaster as they are most vulnerable to flooding.

The ODPEM has a breakdown of which areas are most flood-prone in each county on their website. See the information here.

Source: The Office of Disaster Preparedness & Emergency Management Flood Preparedness Resource Centre