Atlantic hurricane season expected to be stormier than normal

Batten down the hatches we're likely in for a rougher-than-normal Atlantic hurricane season this year, according to Canadian and U.S. hurricane monitoring agencies.

The U.S.-based National Oceanic and Atmospheric Administration (NOAA) says a "weak or non-existent" El Nino is a factor in its prediction.

There is "the potential for a lot of Atlantic storm activity this year," said acting NOAA administrator Ben Friedman. "We cannot stop hurricanes. But, again, we can prepare for them."

Hurricane season officially starts June 1 and runs through Nov. 30. NOAA predicts a 45 per cent chance of having more storm activity than normal this season, a 35 per cent chance of a near-normal season and only a 20 per cent chance of a below-normal season.

Its forecasters say there's a 70 per cent chance of having 11 to 17 named storms this season. Named storms have sustained winds of at least 63 km/h. Of those, five to nine storms could become hurricanes, which have sustained winds of 119 km/h or higher. That includes two to four major hurricanes of Category 3, 4 or 6 with sustained winds of 179 km/h or higher.

According to NOAA, an average season often has 12 named storms of which six may become hurricanes, including three major hurricanes.

This year's numbers will include tropical storm Arlene, a rare pre-season storm that formed over the eastern Atlantic last month.

Bob Robicheau, warning preparedness meteorologist for Environment and Climate Change Canada, said only 35 to 40 per cent of storms that form in the Atlantic make it into the response zone for the Canadian Hurricane centre.

But he said "it only takes that one storm to make it a bad year, regardless of what those numbers say."

He said that's why it's important to be prepared by listening closely to forecasts and warnings as weather approaches, and to have an emergency kit ready to go.

2016 was most active season since 2012

The 2016 season was the most active since 2012, with 15 named storms including seven hurricanes and four major hurricanes. The intervening years, 2013, 2014, 2015, experienced lower than normal or average hurricane seasons.

Robichaud said the Atlantic has experienced particularly active hurricane seasons since 1995. Periods of active seasons generally last 25 or 30 years, but he says it's not clear whether we've come to the end of this active period.

Temperatures right now are warmer than usual for this time of year off Canada's East Coast. Robichaud says that impedes the weakening of storms as they approach the coast.

He also said a storm doesn't have to directly hit to cause damage, giving the example of widespread flooding in Cape Breton and Newfoundland last fall that resulted from the remnants of Hurricane Matthew combining with another low-pressure system.

New tools for NOAA

This year, NOAA is introducing enhanced modelling and forecasting tools including the new GOES-16 satellite, which has a greater image resolution, sharper detail and a quicker refresh rate that offers greater accuracy.

NOAA is also replacing the Geophysical Fluid Dynamics Laboratory Hurricane Model which has been in use for more than 20 years with a new hurricane model called HMON (Hurricanes in a Multi-Scale Ocean-Coupled Non-Hydrostatic). According to NOAA, it has "superior track and intensity forecast skill."