Subtropical Storm “Alpha” forms near the coast of Portugal


Subtropical Storm "Alpha" formed near the coast of Portugal at 16:30 UTC on September 18, 2020. This is the 22nd named storm of the 2020 Atlantic hurricane season and the earliest named 22nd Atlantic storm, breaking the previous record set by Wilma on October 17, 2005. Alpha is expected to be short-lived but bring winds and rain to portions of Portugal.

At the time it formed, the center of Subtropical Storm "Alpha" was located about 125 km (75 miles) N of Lisbon, Portugal.

It had maximum sustained winds of 85 km/h (50 mph) and minimum central pressure of 999 hPa. Alpha was moving NE at 28 km/h (17 mph).

There are currently no coastal tropical cyclone watches or warnings in effect, but interests in Portugal should monitor the progress of this storm.

NE motion is expected during the rest of the day before dissipation.

Alpha should move across the coast of west-central Portugal during the next couple of days.

Subtropical Storm "Alpha" at 14:30 UTC on September 18, 2020. Credit: EUMETSAT/Meteosat-11, RAMMB/CIRA

This is a small storm with winds of 65 km/h (40 mph) extending outward up to 55 km (35 miles) from the center.

This system is expected to produce 25 – 50 mm (1 to 2 inches) of rainfall, with isolated amounts of 75 mm (3 inches) over the northern portion of Portugal and into west-central Spain through Saturday morning, September 19.

Alpha is the earliest 22nd named Atlantic storm, beating Wilma of 2005 by 29 days.

The storm marked the second time in recorded history, together with 2005, that the main naming list has been exhausted and Greek letters were used.

Although the development of a tropical or subtropical cyclone within an extratropical cyclone is rare, it is not unprecedented — the 1991 Perfect Storm and Hurricane "Karl" of 1980 developed in the same manner.

Hurricane "Wilma" (2005) is the most intense tropical cyclone ever recorded in the Atlantic basin, and the second-most intense tropical cyclone recorded in the Western Hemisphere, after Hurricane "Patricia" in 2015.

It was part of the record-breaking 2005 Atlantic hurricane season, which included three of the ten most intense Atlantic hurricanes ever, along with Rita and Katrina. Wilma was the 22nd storm, 13th hurricane, 6th major hurricane, fourth Category 5 hurricane, and the second-most destructive hurricane of the 2005 season. 

Featured image: Subtropical Storm "Alpha" at 14:30 UTC on September 18, 2020. Credit: EUMETSAT/Meteosat-11, RAMMB/CIRA


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