Explained: What is landfall of a cyclone?

Landfall is the event of a tropical cyclone coming onto land after being over water. A tropical cyclone is classified as making landfall when the center of the storm moves cross the coast; in strong tropical cyclones this is when the eye moves over land.

New Delhi, May 11: The India Meteorological Department (IMD) on Wednesday said that the severe Cyclonic Storm 'Asani' weakened into a 'cyclonic storm' and is likely to become a depression by Thursday morning.

"The Severe Cyclonic Storm 'Asani' over westcentral Bay of Bengal moved west-northwestwards with a speed of 12 kmph during the past 6 hours, weakened into a Cyclonic Storm," said IMD.

Asani is also unlikely to make landfall as it is slated to recurve almost parallel to land from May 11 onwards, IMD officials had earlier said unofficially.

What is Landfall of a Cyclone?

As per IMD, Landfall is the event of a tropical cyclone coming onto land after being over water. A tropical cyclone is classified as making landfall when the center of the storm moves cross the coast; in strong tropical cyclones this is when the eye moves over land. This is where most of the damage occurs within a mature tropical cyclone as most of the damaging aspects of these systems are concentrated near the eyewall.

Such effects include the peaking of the storm surge, the core of strong winds comes on shore, and heavy flooding rains. These coupled with high surf can cause major beach erson. When a tropical cyclone makes landfall, the eye closes in upon itself due to the weakening process, which causes surf to decrease. Maximum sustained wind will naturally decrease as the cyclone moved inland due to frictional differences between water and land with the free atmosphere.

A "landfall" should not be confused with a direct hit, as a direct hit is where the core of high winds (or eyewall) comes onshore but the center of the storm may stay offshore. The effects of this are similar to a landfall, as this term is used when the radius of maximum wind within a tropical cyclone moves ashore. These effects are; high surf, heavy rains that may cause flooding, water build up along the coast with minor storm surge, coastal beach erosion, high winds, and possibly severe weather.