Hurricane Lorenzo, also known as Storm Lorenzo for the United Kingdom and Ireland while extratropical, was the easternmost Category 5 Atlantic hurricane on record.[1] Lorenzo was also the largest tropical cyclone observed in the Atlantic since 1995's Hurricane Luis. The twelfth named storm, fifth hurricane, third major hurricane and second Category5 hurricane of the 2019 Atlantic hurricane season, Lorenzo developed from a tropical wave that moved off the west coast of Africa on September 22. On September 26, it rapidly intensified into a Category 4 hurricane before weakening due to an eyewall replacement cycle. After completing the cycle, Lorenzo rapidly re-strengthened, peaking at Category 5 intensity.
Meteorological history
Map plotting the storm's track and intensity, according to the Saffir–Simpson scale
On September 19, the National Hurricane Center (NHC) began to monitor a tropical wave that was forecast to emerge from the west coast of Africa.[2] On September 22, the tropical wave emerged into the Atlantic Ocean.[3] Under favorable conditions, the system quickly organized afterward, and at 03:00 UTC on the next day, the NHC initiated advisories on Tropical Depression Thirteen.[4] Twelve hours later, the depression strengthened to a Tropical Storm and was namedLorenzo south of Cape Verde.[5] Early on September 25, still under favorable conditions, the storm further intensified into a Category1 hurricane.[6] Several hours later, on the same day, Lorenzo further intensified into a Category2 hurricane while initiating an eyewall replacement cycle, which hindered the development of the system somewhat.[7] Early on September 26, the storm completed the cycle and underwent rapid intensification, reaching Category4 status by 15:00 UTC that day. At this point, Lorenzo had become one of the largest and strongest hurricanes on record for the eastern Atlantic in the satellite era—the only comparable hurricane in recent times with similar size and intensity was Gabrielle in 1989.[8] Lorenzo continued to intensify, reaching its initial peak intensity with maximum sustained winds of 145mph (230km/h) and a central pressure of 939mbar (hPa; 27.73inHg) early on September 27.[9] The pressure continued to drop to 937mbar (hPa; 27.67inHg) over the next few hours.
Hurricane Lorenzo near its initial peak intensity on September 26
As Lorenzo began to turn slowly northward, the sea surface temperature dropped slightly and the hurricane weakened with the onset of another eyewall replacement cycle late on September 27.[10] Though sea surface temperature remained at 28 °C (82 °F), strong wind shear continued to disrupt Lorenzo, causing the hurricane to bottom out as a low-end Category3 storm on September 28.[11] Although restrengthening was not forecast due to moderate wind shear and low ocean heat content, Lorenzo defied expectations and re-intensified to a Category4 hurricane upon completing its eyewall replacement.[12] Lorenzo continued to intensify, reaching Category5 strength early on September 29,[13] becoming the easternmost hurricane of such intensity recorded in the Atlantic basin, surpassing Hugo in 1989.[14][1]
Lorenzo’s peak was short lived because of increasing wind shear, cooler waters, an intrusion of dry air, and a third eyewall replacement cycle; the hurricane lost its Category5 status several hours later.[15] This weakening trend became faster as it encountered increasingly hostile conditions. The hurricane's large size upwelled plenty of cool water, and Lorenzo dropped below major hurricane strength early on Septmeber 30.[16] Early on October 2, Lorenzo passed just west of Flores Island, and weakened to a Category1 storm.[17] After passing the Azores, Lorenzo began an extratropical transition as the cloud pattern became increasingly asymmetric in appearance.[18] Lorenzo completed its transition into a powerful extratropical cyclone by 15:00 UTC on October 2.[19]
Preparations and impact
Bourbon Rhode
On September 27, the French ship Bourbon Rhode, with 14 crew members on board, issued a distress signal after sailing through Lorenzo. A NOAA Hurricane Hunter aircraft was diverted from the storm to assist in the search for the ship.[20][21] On September 28, it was confirmed that the ship had sunk. Three crew members were rescued on a lifeboat, but the remaining 11 went missing.[22] Four of the missing crew have been confirmed dead as of October 2.[23]
Azores
Early on September 30, the Instituto Português do Mar e da Atmosfera (IPMA) issued hurricane and tropical storm watches for the Azores,[24] which were upgraded to warnings later that day.[25] Lorenzo was regarded as the strongest storm to hit the islands in 20 years. Wind gusts of 101 mph (163 km/h) were recorded at Corvo Island.[26]
Ireland
Early on October 2, Irish Meteorological Service Met Éireann issued status orange wind warning for six west-most counties with winds expecting to reach mean speeds 65 to 80km/h with gusts generally of 100 to 130km/h, higher in coastal regions. The status orange valid from Thursday 3 October 2019 18:00 GMT to Friday 4 October 2019 03:00 GMT.[27]
United Kingdom
While only arriving as an "ex-hurricane" in the United Kingdom and Ireland, the UK's Met Office said "very strong winds and heavy rain" were expected in western parts of Britain,[28] and issued a weather warning for parts of Northern Ireland,[29] as well as flood warnings for parts of England and Wales.[30]
In addition to being the easternmost Category 5 Atlantic hurricane on record, Lorenzo featured the highest accumulated cyclone energy (ACE) index of any Atlantic tropical cyclone on record to the east of 45°W.[34] Additionally, Lorenzo spent more days as a major hurricane east of 45 °W than any previous cyclone on record, surpassing Carrieof1957.[35] Lorenzo is also the only Category 5 storm in the Atlantic basin to have never made landfall.
^David Zelinsky; Dan Ramos (September 25, 2019). "Hurricane Lorenzo Discussion Number 10". www.nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved September 28, 2019.
^Andrew Latto (September 25, 2019). "Hurricane Lorenzo Discussion Number 13". www.nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved September 28, 2019.
^John Beven (September 27, 2019). "Hurricane Lorenzo Discussion Number 20". www.nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved September 28, 2019.
^David Zelinsky (September 28, 2019). "Hurricane Lorenzo Discussion Number 23". www.nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved September 28, 2019.
^Robbie Berg (September 28, 2019). "Hurricane Lorenzo Discussion Number 25". www.nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved September 28, 2019.
^Daniel Brown; Andrew Latto (September 28, 2019). "Hurricane Lorenzo Tropical Cyclone Update". www.nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved September 28, 2019.
^Andrew Latto (September 29, 2019). "Hurricane Lorenzo Discussion Number 27". www.nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved September 29, 2019.
^John Cangialosi (September 29, 2019). "Hurricane Lorenzo Discussion Number 28". www.nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved September 29, 2019.
^Eric Blake (September 30, 2019). "Hurricane Lorenzo Discussion Number 31". www.nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved September 30, 2019.
^Stacy R. Stewart (October 2, 2019). "Hurricane Lorenzo Advisory Number 39A". www.nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved October 2, 2019.
^Eric Blake (September 30, 2019). "Hurricane Lorenzo Advisory Number 31". www.nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved September 30, 2019.
^Andrew Latto (September 30, 2019). "Hurricane Lorenzo Advisory Number 33". www.nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved September 30, 2019.