Last week, NOAA reported that it had found a possible first storm of 2023. National Hurricane Center specialists doing a routine re-assessment of a system that developed off the east coast of the U.S. in mid-January found that it met the standards (central pressure, wind speed) to be called a cyclone. However, it didn’t get far enough south to be a “tropical” storm, so it won’t get a name though it will be counted as the first Atlantic storm of the year.
To count as “tropical” a storm must develop or spend most of its life somewhere between the Tropic of Cancer in the north and the Tropic of Capricorn in the south. These are imaginary lines of latitude, about 23.5 degrees away from the Equator. The Tropic of Cancer marks the location where the sun is directly overhead at the June solstice. At the December solstice the sun is directly over the Tropic of Capricorn and the Tropic of Cancer is turned directly away. The Tropic of Cancer passes through the Caribbean basin just north of Cuba and the Yucatan Peninsula and exits through central Mexico.
So we are still waiting for Tropical Storm (or Hurricane) Arlene, with the official start of the season just around the corner. NOAA will be publishing its official forecast this week but no big surprises are expected. The Agency is hanging its hat on a return of El Niño. This warm current in the eastern Pacific produces updrafts and wind shear that weaken or destroy storms in the southwestern Caribbean. NOAA’s numbers are likely to be in line with the consensus forecast – about a dozen named storms, of which six will be hurricanes including two big ones.
This is a bit less than average activity, but the producers of these forecasts caution against feeling safe. They point out that the El Niño provides some protection for Central America and the western Gulf of Mexico, but the sea surface in the south Atlantic and eastern Caribbean is warm and getting warmer all the time.
According to Weatherbell’s Joe Bastardi, 2023 could be a unique El Niño year. “My take is that the Atlantic is warm enough that the farther away from the Main Development Region the more the chance for development relative to normal. That could cause a feeding frenzy near our coasts with in-close development. As long as the Atlantic is warm that will always be a concern, but an El Niño is no cause for relaxation.”
Hurricane insurance specialist Andrew Siffert notes that models are forecasting unusual rainfall patterns both in the main hurricane development region off the African coast and off the east coast of the U.S. and Florida and Bahamas. These precipitation anomalies “could mean storms develop early and recurve into the Atlantic with maybe some close to home development off the southeast coastline during the hurricane season,” Siffert explained.
“Close-to-home development”, also called “rapid intensification,” has become an increasingly common feature of major storms in recent years. As these storms approach land, the water under them gets shallower and warmer, pumping energy into the system.
They hit land blowing harder and loaded with more rain – in 2022 both Fiona and Ian went from Tropical Storm to Major Hurricane in less than two days. Everybody agrees that there is more than the usual degree of uncertainty about this year’s storm season outlook.
It only takes one near miss to make a real mess, and it’s not too late to get ready. NOAA this year has done a particularly good job on materials for its annual Hurricane Preparedness Week. The website www.weather.gov/safety has some excellent checklists of things to have and things to do that may save your property and your life.