The slower onset of El Niño and record-breaking warm ocean temperatures may lead to a busier than normal Atlantic hurricane season in 2023, the National Oceanic and Atmospheric Administration (NOAA) said Thursday.
In its annual hurricane update that comes in August after an initial May outlook, NOAA increased the likelihood that there will be an “above normal” hurricane season to 60 per cent, up from a 30 per cent chance in May.
The agency said there could be 14 to 21 named storms, six to 11 hurricanes and two to five major hurricanes. Major hurricanes are ones that reach Category 3 to 5 and have winds of 111 miles per hour or greater. It gave a 25 per cent chance of a near-normal hurricane season, down from 40 per cent, and a 15 per cent chance of below normal. The forecast is given with 70 per cent confidence.
This year so far has had an “active start” with five tropical storms, including one hurricane.
NOAA’s lead seasonal hurricane forecaster Matthew Rosencrans said Thursday that we are now entering the peak hurricane months from August to October, when 90 per cent of hurricane activity happens. The hurricane season goes until the end of November and typically produces 14 named storms, of which seven become hurricanes and three are major hurricanes.
While El Niño typically lessens the severity of the hurricane season, this year’s has had a slower onset so far, which has negated its effect, Rosencrans said. Normally with El Niño there would be two named storms, whereas there have already been five this year, he pointed out.
Further negating El Niño’s effects and increasing the likelihood of a hectic hurricane season is record Atlantic water temperatures. Rosencrans said sea surface temperatures in June and July this year have been the warmest since 1950, when analysis began. It has been 1.23 C above normal.
“Every year between 1950 and now was cooler than the (Atlantic) temperatures now,” he said. “Warm waters are conducive to more development.”
Rosencrans said the warmer water likely contributed to the development of two tropical storms in the deep tropics in June. Tropical storms there in June and July are “usually a harbinger of a busy season to follow,” he said.
Atlantic hurricanes often form in the warm waters of the Gulf of Mexico or the Caribbean and can sweep up the east coast to Canada. Areas of Canada’s East Coast continue to recover from 2022’s hurricane Fiona.
A Canadian forecaster says the revised outlook increases the chance of a significant storm hitting Eastern Canada.
“A possibility of more storms than normal as we go into the peak of the hurricane season also increases the possibility that one of those storms will make it up to our neck of the woods in Eastern Canada,” Chris Fogarty, who heads the Canadian Hurricane Centre in Dartmouth, N.S., said in an interview Friday.
He said the biggest concern right now would be the forming of a wet tropical system that forms into a hurricane, given the humid air mass that has hovered over Nova Scotia, in particular, since July. Torrential rains that caused massive flooding last month have saturated the ground, making some areas even more susceptible to flooding during a significant storm such as a hurricane, Fogarty said.
“If this humidity sticks around into hurricane season, that’s not good because the rain threat will be higher if a storm does move into our region.”
Active tropical storm and hurricane seasons double the number of landfalls along the U.S. east coast, Rosencrans said.
This summer has so far broken global heat records in June and July, while places around the world have been dealing with wildfires that thrive on hot, dry conditions. The island of Maui in Hawaii is currently in an emergency state as wildfires have killed at least 36 people after they spread very quickly partly due to strong winds from hurricane Dora.
Since the Atlantic water temperature is at a new high, Rosencrans said there are no analogs in the past to compare what the effects might be, but said 2004 also had El Niño and warm waters. That year had 15 tropical storms, nine hurricanes and six major hurricanes — 200 per cent above normal, according to Rosencrans.
NOAA urges people to prepare for the hurricane season, which can produce damaging winds and flooding.
“It really only takes one storm for devastating impacts,” Rosencrans said.
— With files from the Canadian Press.