Apparently during the night, the oceans explode with the activity of tropical cyclones

What has also changed over the past two weeks is the amount of instability – or "juice" – with which the storms had to work. Until two weeks ago, we were well below average. Then suddenly, a switch rocked and the results were explosive.

The Category 4 Hurricane Florence is on a rugged course with the Carolinas coast. As the orientation currents in the atmosphere relax this weekend, there is growing concern that Florence could slow down, prolonging its dam and producing catastrophic rainfall.

[Hurricane Florence charges toward Carolinas with ‘potential for unbelievable damage’]

Florence has a company in the Atlantic. Helene is a category 1 west of Cabo Verde, offering winds of 90 mph. Although the storm is impressive by satellite, it should stay above the ocean. The storm is likely to be blown into the jet stream over the weekend, likely due to heavy rains in the middle of next week.

Isaac is also spinning. The tropical storm will cause gusts of 60 km / h on the Lesser Antilles before passing well south of Cuba and Puerto Rico in the Caribbean.

Overwhelmed yet? But wait – there is more.

We also look not one but two additional systems in the Atlantic. A disturbance posted off the Yucatán peninsula may become a tropical depression this weekend. The National Meteorological Service can send an air force reconnaissance aircraft to sound the system on Wednesday. The National Hurricane Center advises residents of the Texas and Louisiana coasts to monitor the system.

An additional wave of low pressure several hundred kilometers southwest of the Azores may also develop tropical or subtropical characteristics in the next two days, but it poses no immediate threat to any land.

If the other two systems of the Atlantic were transformed into tropical storms, there could be five cyclones simultaneously. It never happened once – between September 10 and 12, 1971.

In the Pacific, the Super Typhoon Mangkhut produces 170 mph winds and huge waves as it travels about 200 miles west of Guam. The monster storm is expected to mark Friday the northern Philippines as the equivalent of a strong hurricane category 5.

This is not the only storm off the coast of China. Tropical storm Barijat will pass south of Hong Kong on Wednesday. Hong Kong will also be in close contact with Mangkhut, which is expected to pass near the city of 7 million at weekends, likely as a low-end category 1 equivalent.

Hawaii is facing its own threat in the Pacific. Tropical storm Olivia invades the archipelago with up to 15 inches of rain in places. Just two weeks ago, Hawaii set a state record of total storm precipitation for all time – an astonishing 52.02 inches of Hurricane Lane. With the tropical paradise under arms, it is not surprising that climate change is driving more storms to Hawaii in the coming years.

Two additional systems have developed in the west of Mexico – Paul, a tropical depression and an area to watch over in the east. Both seem to remain rather docile at this stage.

So by combining all these tropical storm actions, how does it compare to what is normal?

The accumulated energy of the cyclone, or ACE, is a measure that combines the duration and intensity of storms. In the northern hemisphere, the year is 159% of the average for the date. The largest contribution to the anomaly comes from the eastern Pacific (245% of the average), followed by the western Pacific (124% of the average) – the Atlantic and Indian Oceans are both slightly above their climatological averages.

This renewed activity in mid-September, however, is not a big surprise. If we look at the chronology of historical activity in each of the major basins, this time of year is not unrelated to the action:

• The West Pacific can experience storms throughout the year, but peaks from July to October.
• The hurricane season in the eastern Pacific is not as long (mid-May to late November) and peaks in August and September.
• The Atlantic season is the shortest of all (June to November) and its peak is much narrower in the first half of September.

So, at the present time, the activity of tropical storms is usually high in all these basins.

Annual time series of tropical cyclone activity in the three main basins of the northern hemisphere: West Pacific (high), Eastern Pacific (Middle), Atlantic (low). (NOAA / HRD)

• The Atlantic has been above average for the entire season until August 21st. Things slowed down and did not reach the normal level until Tuesday.
• The Eastern Pacific and Central Pacific are well above average since June (with the exception of a brief boost below the average at the end of July).
• The Western Pacific has hovered around the average throughout its season, but it is currently high.
• The North Indian Ocean is above average since the end of May, although its normal activity is quite low anyway.

What does all this mean in terms of climate? The answer is not clear. Research suggests that the number storms that develop will not change significantly due to climate change. Instead, it is likely that those who develop might become stronger and stronger. Be that as it may, one thing is clear: what happens in the tropics around the world is not ordinary.