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How to Classify a Tropical Storm

A tropical storm is classified based on two factors: its geographical location and sustained wind speed. Depending on its geographical latitude and whether it is formed in the Atlantic or Pacific ocean, the storm will be classified according to one of six classification systems. The NHC Saffir-Simpson scale is used for the Atlantic and East Pacific regions. The Regional Specialized Meteorological Center (RSMC) specifies unique classification systems for the other five major basins in India, Australia and East Asia. All seven classification systems have three categories: tropical depression, tropical storm and cyclone/hurricane/typhoon.

Instructions

Classifying the Storm
- 1
  Determine the geographical region of the tropical storm's origination. Storms occurring in the Atlantic basin and East Pacific are classified according to the Saffir-Simpson Tropical Cyclone Scale. Tropical storms occurring in India, Asia and Australia are classified according to the RSMC scale for that region.
- 2
  Determine the maximum sustained wind speed of the tropical storm. A sustained wind is the average surface wind speed over two minutes. Hurricane advisories will usually report the maximum sustained wind speed.
- 3
  Convert the wind speed to the proper units. The Saffir-Simpson Tropical Storm scale uses miles per hour; the RSMC uses kilometers per hour.
- 4
  Find the storm category that matches the observed maximum wind speed of the tropical storm. The Saffir-Simpson scale classifies wind speeds from 30 to 49 mph as a weak tropical storm, speeds from 50 to 73 mph as a severe tropical storm and speeds greater than 74 mph as a hurricane. The RSMC uses the same wind speed ranges (converted to km/h), but uses the labels "cyclonic storm" and "tropical cyclone" or "severe cyclonic storm" and "severe tropical cyclone," depending on the region.

Nature