At their worst, storm floods fill entire cities with water, tear apart houses and take people with them.
The destruction of the latest hurricane Milton is only beginning to be properly mapped, but the Atlantic hurricane season still has a month and a half left. Typically, hurricane season ends by the end of November.
Milton, which was hitting Florida, was feared to bring powerful storm surges up to 4.5 meters high. The floods were smaller than expected, and Milton has already continued to the sea.
The United States Meteorological Administration saysthat according to preliminary measurements, the water level rose up to three meters above normal in part of Florida during Milton. Just weeks earlier, the devastating hurricane Helene also raised the sea water level by several meters.
During hurricanes, the winds blow at life-threatening speeds, but the resulting storm surges can be even more dangerous than the winds.
In the United States, storm surges are the biggest cause of death during hurricanes, says United States Atmospheric Administration.
This is how storm surges occur
The meteorologist of Aleksi Lohtander shed light on ‘s morning on Thursday, how storm surges occur during hurricanes.
There are two factors behind them: wind and air pressure.
A strong wind collects water from the sea and pushes water masses towards the coast. Meanwhile, the air pressure is low in the center of the hurricane.
– There is less air pressing down on it. It raises the water level, Lohtander said.
The effect of a storm surge is doubled if it coincides with the daily high tide.
Hurricane Milton also brought heavy rains. The amount of rain in St. Petersburg, located on the west coast of Florida, was a record on Wednesday, more than 46 centimeters.
For the sake of comparison, it should be mentioned that it also rained heavily in Finland on Wednesday during the storm. At that time, the highest water volume of the day was measured in Espoo’s Tapiola: 52.7 millimeters. Still, that’s only a good tenth of Milton’s heavy rains.
Such destruction is caused by storm surges
During hurricanes, urban flooding is mainly caused by storm floods. They can cause significant damage to buildings and infrastructure on the coast and inland.
During hurricanes, stormwater floods streets and buildings, uprooting houses and carrying people and hazardous waste with them.
Even a 15-centimeter-high flood is enough to knock over an adult person, and a 30-centimeter-high flood current will sweep away a car. At a height of about 1.5 meters, the flood already swallows the whole car under it.
Especially the hurricane areas of the Gulf of Mexico and Atlantic coasts are very low compared to the sea level. That’s why storm surges raised by hurricanes cause significant destruction in their residential areas, he says US National Oceanic and Atmospheric Administration NOAA.
A storm surge of 4.5 meters that hit Florida would have been enough to engulf entire single-family houses, warned the mayor of the city of Tampa Jane Castor from the beginning of the week. The worst-case scenario didn’t materialize, but Milton still left behind flood damage.
Sources: Noah.gov, weather.gov, CNN