Hurricane Debby could bring ‘catastrophic flooding’ to southeast US
Hurricane Debby hits Florida
Hurricane Debby – the fourth named storm of the Atlantic hurricane season – made landfall in the Big Bend of Florida on Monday morning (local US time).
The category one storm started to form late last week over the Caribbean, before growing in strength and intensity over the Gulf of Mexico during the weekend.
Whilst not a particularly powerful storm in terms of wind, it is going to be a huge rainmaker in the coming days over the southeastern states of the US.
A slow-moving storm
Typically, tropical storms and hurricanes have a steady forward movement, so when they hit, the impacts, whilst significant, tend to be relatively short-lived.
However, every now and then, there are instances where they become very slow-moving or even stuck. This is what is going to happen with soon-to-be Tropical Storm Debby.
The steering flow, the winds which push it along, are going to be very light – leading to torrential rain across Florida, Georgia, South Carolina and parts of North Carolina for a prolonged period of time.
You can see in the National Hurricane Center warning below, issued on Monday 5 August, that the storm makes very little progress between Monday and Thursday.
Catastrophic flood risk
Due to the slow-moving nature of Debby, the National Hurricane Center has predicted that ‘potentially historic’ amounts of rain could fall over the previously mentioned states in the southeast of the US.
By the end of the week, 10-20 inches (25-50cm) of rain could fall widely, with 20-30 inches (50-75cm) possible for areas close to the east coast. To put this into perspective, London’s annual rainfall is around 60cm.
Such a huge amount of rain could cause catastrophic flooding, with the risk of flash flooding considered high across a vast area stretching around 300 miles.
According to a 2014 study by Edward Rappaport, which looked at the cause of hurricane deaths for 1963-2012, freshwater flooding from rain was the second-biggest killer at 27%. It was only surpassed by storm surge – responsible for 49% of deaths.
Will it affect the UK’s weather?
Sometimes, the remnants of tropical storms and hurricanes can interact with the jet stream and have an impact on the UK’s weather down the line – usually 7-10 days later.
However, there is so much uncertainty with exactly where this storm ends up later this week, that it’s currently not possible to say with any certainty what impact, if any, it will have on our weather in the next fortnight.
It may take until the end of the week before this aspect of the forecast becomes any clearer.
When is peak of hurricane season?
Atlantic hurricane activity typically starts to increase through August, with a crescendo to a statistical peak around the middle of September.
Due to record-warm oceans – from which hurricanes gain their energy – this year’s hurricane season is expected to be extremely active.
Therefore, all eyes will closely be on the Atlantic Ocean in the coming weeks, looking for signs of any more potential storms that could develop.