Tropical Storm Arlene, the first named storm of the 2017 Atlantic Hurricane Season, continues to march west. While its westward path may look concerning on a map for those on the US east coast; there’s nothing to worry about: Arlene should be absorbed by an extratropical low and dissipate today without having the chance to impact any landmass.
The current low pressure inside Arlene of 993mb is the lowest pressure ever recorded for a tropical or subtropical cyclone in April in the Atlantic.
Arlene has maintained a small area of deep convection surrounding the center of the cyclone, with some of the cloud tops as cold as -50 degrees C. However, satellite trends over the past couple of hours indicate that the areal coverage of the convection has decreased
significantly since overnight satellite intensity estimates, an indication that Arlene is beginning to lose its tropical characteristics as the cyclone interacts with a frontal zone and also moves over cooler water. Arlene has accelerated westward during the past 6 hours as the cyclone moves around the northern periphery of a larger deep-layer extratropical low that has remained nearly stationary near 36N 48W. The small cyclone or its remnants are expected to move in a cyclonic loop around this low for the next couple of days.
Arlene is gradually running out of space within the narrow warm sector of the aforementioned occluded low pressure system, and merger with one or more frontal zones is likely during the next 12 hours. The new official intensity forecast continues the trend of the previous advisory, which shows Arlene degenerating to a post-tropical cyclone by 12 hours, and dissipating by 24 hours when the system is expected to be absorbed into the larger baroclinic low.
Tropical storms in April are rare and Arlene is only the second one observed in this month during the satellite era. The National Hurricane Center is quick to point out that this type of storm was practically impossible to detect prior to the weather satellite era. The last April tropical cyclone in the Atlantic basin was Ana in 2003. Ana brushed by Bermuda then but brought no heavy rain or strong winds to any landmass during its lifecycle. In addition to 2 storms, there were 3 other subtropical or tropical depressions in recorded history in April. April storm systems are not indicative of the activity a season will see.
The 2017 Atlantic Hurricane season doesn’t officially kick off until June 1. Regardless of Arlene, experts believe there will be a slightly less active hurricane season this year in the Atlantic basin.
While Arlene is not expected to impact any land, the US included, the National Oceanic and Atmospheric Administration and the US Air Force are deploying a Hurricane Hunter Tour along the east coast in early May to bring awareness to the upcoming season and preparations people should make prior to a storm threat. More details on that tour can be found here.