At a Glance

A storm system off the East Coast in mid-January has been deemed an unnamed subtropical storm.Arlene will still be the name given to the Atlantic's next storm.The Atlantic recently had a hurricane form in January.

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The Atlantic hurricane season started early with the first storm forming in January, .​

A​n unnamed subtropical storm formed in mid-January. A powerful storm system off the East Coast had its area of low pressure obtain enough thunderstorms near its core to be deemed a hybrid subtropical storm, as depicted in the yellow and orange shadings in the from the evening of Jan. 16.

"Through the course of typical re-assessment of weather systems in the National Hurricane Center's area of responsibility, NHC hurricane specialists have determined that an area of low pressure that formed off the northeastern coast of the United States in mid-January should be designated as a subtropical storm," the NHC said in a statement.

Subtropical storms are usually named in real-time. Subtropical storms have characteristics of both tropical storms and the more commonly seen non-tropical low-pressure systems. They are usually assigned a number or name, just like a tropical depression or storm.

T​his one was tracked in real-time by NOAA and was deemed Invest 90L, . But since it was a marginal case, it was not named one at that time.

(​MORE: Meteorology 101: Learn About Subtropical Storms)

A​rlene will still be the name of the Atlantic's next storm. Since this subtropical storm wasn't named in January, and systems like this one aren't named when they are reassessed, the next storm to form in the Atlantic will be given the name Arlene.

I​f the next Atlantic system is initially a tropical depression, it will be called Tropical Depression Two.

(​MORE: Atlantic Hurricane Season Outlook)

January storms are rare, but the month recently had a hurricane. In January 2016, .​ It eventually made landfall in the Azores as a tropical storm.

Only five other Atlantic storms have existed in January since record-keeping began.

H​urricane season officially begins June 1, but storms forming before that date have been common in recent years. to have at least one storm form prior to that date.

Here are the six storms or hurricanes that either formed in January, or were in progress into January, in records dating to 1842.

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