The early morning update says there's a 60 percent chance that the disturbed area will develop as early as this afternoon or early Tuesday morning.
By late Tuesday or early Wednesday, the storm is likely to merge into a cold front moving offshore from the U.S. Eastern Seaboard and will lose its tropical characteristics - and its status as a tropical system - at that time.
An Air Force Reserve reconnaissance plane provided data that showed the low pressure system had strengthened, with a well-defined center and maximum sustained winds of about 40 miles per hour.
It poses no threat to South Florida or the USA, though people with interests in Bermuda will want to monitor this system.
At 630 PM AST (2230 UTC), the center of Subtropical Storm Andrea was located near latitude 28.8 North, longitude 68.7 West.
In 2017, Tropical Storm Arlene formed April 20 as the first named storm of the year and only the second tropical storm on record to form in April, joining Ana, which formed in 2003.
This satellite image provided by NOAA shows Hurricane Michael (C), in the Gulf of Mexico on October 9, 2018.
"Of those storms, five to seven are forecast to become hurricanes and two to four are forecast to become major hurricanes", AccuWeather said. Hurricane season runs from June 1 through November 30. A hurricane watch is issued 48 hours in advance of the anticipated onset of tropical-storm-force winds.
The subtropical storm makes 2019 the fifth consecutive year with a preseason named storm, following Ana in 2015, Bonnie in 2016, Arlene in 2017 and Alberto in 2018. Michael recently was upgraded to a Category 5 after the National Weather Service analyzed it.