Florence is nation’s second wettest storm, behind Harvey


Hurricane Florence was the nation’s second rainiest storm in 70 years, a top rainfall meteorologist calculated.

Only last year’s Hurricane Harvey rained more over a 14,000 square mile (36,260 square kilometers) area during a four-day time period, said Ken Kunkel, a meteorologist at the National Oceanic Atmospheric Administration and North Carolina State University.

Scientists said climate change likely boosted rainfall totals for both storms.


An economic research firm estimated that Florence has caused around $44billion in damage and lost output, which would make it one of the top 10 costliest US hurricanes. 

The top disaster, Hurricane Katrina in 2005, cost $192.2billion in today’s dollars, while last year’s Hurricane Harvey cost $133.5billion.

Moody’s Analytics estimates Florence has caused $40billion in damage and $4billion in lost economic output, though the company stressed that the estimate is preliminary. 

Kunkel’s preliminary analysis found more than 17.5 inches (0.4 meters) fell on average over five weather stations in the 14,000 square miles of the eastern Carolinas stretching from Fayetteville, North Carolina, to Florence, South Carolina. 

The amount is second to Harvey’s 25.6 inches (0.6 meters).

‘That’s a lot of water,’ Kunkel said.

The third rainiest storm was in March 2016 in northern Louisiana and the seventh was in southern Louisiana in August 2016. 

The three rainiest and four of the top seven have all occurred in the last three years — which Kunkel said is no coincidence.

Kunkel, who specializes in analyzing rain data from thousands of weather stations, based his work on rainfall since 1949 when recording became more widespread across the continental United States.

Kunkel examined rainfall over a compact area — 14,000 square miles, a figure based on latitude and longitude squares — and larger areas such as 20,000, 30,000 and 80,000 square miles. 

Florence’s unusual amount was most noticeable on the smallest scale.

When the scientist looked at a bigger area, 20,000 square miles, Florence fell to seventh place, behind Harvey, 1998′s Hurricane Georges, the two Louisiana rainstorms, a 1962 northern California downpour and a 1994 Texas drenching.

The analysis has not been published or peer reviewed yet, but will be, Kunkel said.


Hurricane Harvey’s biggest effect is through its intense and prolonged rainfall. A low pressure system to the north is keeping Harvey over southern Texas, resulting in greater rainfall totals. 

We know that . As the atmosphere is getting warmer, it can hold more moisture (roughly 7 per cent for every 1℃ rise in temperature). 

This means that when we get the right circumstances for very extreme rainfall to occur, climate change is likely to make these events even worse than they would have been otherwise. 

Without a full analysis it is hard to put exact numbers on this effect, but on a basic level, wetter skies mean more intense rain.

But there are also other factors that are making this story worse than others in terms of its impact. 

Houston is the second-fastest growing city in the US, and the fourth most populous overall.

As the region’s population grows, more and . 

This means that when there is extreme rainfall, the water takes longer to drain away, prolonging and intensifying the floods.  

It is ‘not surprising — but still terrifying — that the two top ranked soakers happened over the past two years,’ said Pennsylvania State University climate scientist Michael Mann, who wasn’t part of Kunkel’s research but praised it. 

He said warmer oceans, more moisture and slower moving storms due in various ways to climate change make storms dump more rain.



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