The freshly formed Tropical Storm Leslie is heading in the direction of the East Coast as it intensifies, current National Hurricane Center (NHC) forecasts predict.
The storm, which currently has wind speeds of 40 mph, is forecast to strengthen into a hurricane by Saturday.
Leslie (originally Tropical Depression Thirteen) was named after it intensified to tropical storm strength on Wednesday night, having formed in the Central Atlantic in the wake of Hurricane Kirk.
"Strengthening is anticipated, and Leslie is forecast to become a hurricane in a couple of days," the NHC said in a public advisory. "A slow westward motion is expected through tonight, followed by a slightly faster west-northwestward motion Friday through Saturday."
Leslie formed close behind Hurricane Kirk, which is now getting further and further away as it picks up speed. This increasing distance between the two storms may help Leslie strengthen into a hurricane, due to decreased wind shear.
"As the distance between Kirk and slow-moving Leslie grows, the wind shear over Leslie should diminish. This will provide a more conducive environment for the storm to steadily strengthen within a moist environment over warm waters," the NHC said in a forecast discussion.
Low wind shear, as well as sea surface temperatures and atmospheric moisture, are key factors that affect whether a storm will intensify into a hurricane, and how strong that hurricane might get.
"TCs [tropical cyclones] primarily thrive from the following atmospheric ingredients: Warm [sea surface temperatures] (usually the "magic number" for warm enough [sea surface temperatures] is 80 F) and a sufficiently deep layer of warm water, all serving as a key source of energy for a TC, [as well as] weak middle and upper level atmospheric winds (as TC's prefer a very vertical and symmetrical structure and do not survive when that structure is tilted in the vertical)," Zachary Handlos, an atmospheric scientist at Georgia Institute of Technology, told Newsweek.
"Sufficient moisture in the air in the lower and middle levels of the atmosphere, and the cluster of thunderstorm activity that forms a TC must form at least 5 degree latitude or farther from the equator, as then the rotational effects of Earth have an impact on the wind and the generation of a circulation for the TC."
Hurricane Kirk, which is now at Category 3 strength with wind speeds of 120 mph, was originally forecast to head towards the U.S., but has since veered to the north and then the northeast, and is heading back across the Atlantic in the direction of Ireland and the U.K.
Despite not making landfall in the U.S., Kirk may have some impacts along the east coast, whipping up powerful waves.
"Swells generated by Kirk are spreading westward and are expected to reach portions of the Leeward Islands on Friday, Bermuda and the Greater Antilles on Saturday, and the east coast of the United States and the Bahamas on Sunday. These swells are likely to cause life-threatening surf and rip current conditions," the NHC said.
If Leslie follows the same veering path as Kirk, it may not strengthen as intensely as it might if it continues its current path toward the U.S.
"The intensity of Leslie could plateau thereafter if it follows a similar track to Kirk and encounters the cool wake left behind by the hurricane," the NHC explained.
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