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Hurricane Alex (2016)

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This article is about the 2016 hurricane. For other storms of the same name, see Tropical Storm Alex.
Hurricane Alex
Category 1 hurricane (SSHWS/NWS)
Hurricane Alex at peak intensity south of the Azores on January 14
FormedJanuary 12, 2016 (January 12, 2016)
DissipatedJanuary 17, 2016 (January 17, 2016)
(Extratropical after January 15)
Highest winds1-minute sustained: 85 mph (140 km/h)
Lowest pressure981 mbar (hPa); 28.97 inHg
Fatalities1 indirect
DamageMinimal
Areas affected
Part of the 2016 Atlantic hurricane season

Hurricane Alex was the first Atlantic hurricane to occur in January since Hurricane Alice in 1955. Alex originated as an non-tropical low near the Bahamas on January 7, 2016. Initially traveling northeast, the system passed by Bermuda on January 8 before turning southeast and deepening. It briefly acquired hurricane-force winds by January 10, then weakened slightly before curving east and northeast. Acquiring tropical weather characteristics over time, the system transitioned into a subtropical cyclone on January 12 well south of the Azores, becoming the first North Atlantic tropical or subtropical cyclone during January in the since Tropical Storm Zeta in 2006. Alex continued to develop tropical features while turning north-northeast, becoming a fully tropical cyclone on January 14. The cyclone peaked in strength as a Category 1 hurricane on the Saffir–Simpson scale with maximum sustained winds of 85 mph (140 km/h) and a central pressure of 981 mbar (hPa; 28.97 inHg). Alex weakened to a high-end tropical storm before making landfall on Terceira Island on January 15. By that time, the storm was losing its tropical characteristics; it fully transitioned back into a non-tropical cyclone several hours after moving away from the Azores. Alex ultimately merged with another non-tropical cyclone over the Labrador Sea on January 17.

The precursor cyclone to Hurricane Alex brought stormy conditions to Bermuda from January 7 to 9. On its approach, the hurricane prompted hurricane and tropical storm warnings and the closure of schools and businesses for the Azores. Alex brought gusty winds and heavy rain to the archipelago, though structural damage was generally minor. One person died of a heart attack because the inclement weather prevented them from being transported to hospital in time.

Background and records

As currently defined, the Atlantic hurricane season lasts from June 1 to November 30, the period in which tropical cyclones are most likely to develop across the basin. Occasionally, systems develop outside these seasons,[1] most frequently in May or December.[2] Activity in January is extremely rare, with only five systems other than Alex recorded since 1851: an unnamed hurricane in 1938, an unnamed tropical storm in 1951, Hurricane Alice in 1954–55, an unnamed subtropical storm in 1978, and Tropical Storm Zeta in 2005–06.[3] Because Alice formed in December 1954 and persisted into January 1955, Alex is only the second hurricane after the unnamed storm of 1938 to originate within January.[3][4]

Alex's landfall on Terceira as a strong tropical storm marked only the second such occurrence for an Atlantic tropical cyclone in January – after Hurricane Alice of 1955, which made landfall on the islands of Saint Martin and Saba.[5] Equally unseasonable as the time of its formation was its location: Alex became only the second hurricane on record to form north of 30°N and east of 30°W.[6] Alex was the first hurricane to impact the Azores since Hurricane Gordon in 2012, and the only recorded hurricane to track within 230 mi (370 km) of the Azores outside the usual activity period between August and September.[7][8]

Unrelated to Alex, the formation of Hurricane Pali over the Central Pacific in early January coincided with Alex's development over the Atlantic. This marked the first occurrence of simultaneous January tropical cyclones between these two basins.[3]

Meteorological history

Map plotting the storm's track and intensity, according to the Saffir–Simpson scale
Map key
Saffir–Simpson scale
  Tropical depression (≤38 mph, ≤62 km/h)
  Tropical storm (39–73 mph, 63–118 km/h)
  Category 1 (74–95 mph, 119–153 km/h)
  Category 2 (96–110 mph, 154–177 km/h)
  Category 3 (111–129 mph, 178–208 km/h)
  Category 4 (130–156 mph, 209–251 km/h)
  Category 5 (≥157 mph, ≥252 km/h)
  Unknown
Storm type
triangle Extratropical cyclone, remnant low, tropical disturbance, or monsoon depression

In early January 2016, a stationary front spanned across the western Caribbean, spawning a non-tropical low along its boundary over northwestern Cuba by January 6.[9][10] The low moved northeast ahead of the subtropical jet stream the following day, when its interaction with a shortwave trough produced a cyclonic disturbance at the lower atmospheric levels northeast of the Bahamas.[9][11] This system proceeded northeast toward Bermuda, where unfavorable atmospheric conditions such as strong wind shear, low sea surface temperatures, and dry air initially inhibited tropical cyclone formation.[12][11] The system featured a large field of gale-force winds, with maximum sustained winds of 60–65 mph (95–100 km/h).[12] On January 8, it passed about 75 mi (120 km) north of Bermuda, bringing strong winds and heavy rain to the islands.[13] The next day, an anomalous blocking pattern prevented the disturbance from continuing along a seasonal northeasterly track. Instead, the system turned east-southeast into a region slightly more favorable for subtropical development.[9][14] On January 10, surface pressures below the system's core deepened to 979 mbar (hPa; 28.91 inHg) as the surrounding winds reached hurricane-force.[9] Concurrently, a warm-core seclusion at the upper-levels marked the transition to a more symmetric structure,[15] although convective activity near the center remained sparse.[16] Once separated from the jet stream, the cyclone turned to the south-southeast in response to a mid-latitude trough over the central Atlantic,[9][3] entering a region with warmer waters of 2.7 °F (1.5 °C) above average for January.[9][17] Slight weakening took place on January 11.[18]

The system underwent substantial changes to its cyclonic structure on January 12: frontal boundaries separated from the core of the cyclone;[9] its core became symmetric;[15] and convection developed atop the circulation.[9] All these factors, alongside the system being co-located with an upper-level low, indicated its transition into a subtropical cyclone by 18:00 UTC, receiving the name Alex from the National Hurricane Center.[9] Though relatively shallow, owing to the seasonally low level of the tropopause,[nb 1] convection was deemed intense enough for classification.[21] At this time, the subtropical storm was situated 1,150 mi (1,850 km) west-southwest of the Canary Islands.[9] The trough that previously enabled the sharp southward turn later steered Alex to the east-northeast and eventually north-northeast.[9][21] Operationally, Alex was not classified as a subtropical storm until late on January 13.[21]

An eye feature soon appeared within a complex of several banding features, marking intensification.[22] The 20 mi (25 km) wide feature cleared out early on January 14 and was surrounded by a ring of −75 °F (−60 °C) cloud tops. Alex then began to move away from the upper-level low it had been situated under, allowing the cyclone to acquire a deeper warm core with upper-level outflow typical of more tropical systems.[9][23] Despite moving over 72 °F (22 °C) waters,[nb 2] Alex continued to deepen and became a fully tropical cyclone by 06:00 UTC[9] – a transition that was supported by greater instability than usual for tropical cyclones due to colder upper-tropospheric temperatures than those around the equator.[4][9] Upon the storm's transition, Dvorak satellite estimates indicated that Alex had achieved hurricane strength. The hurricane achieved its peak intensity as a tropical cyclone with winds of 85 mph (140 km/h) and a minimum barometric pressure of 981 mbar (hPa; 28.97 inHg) soon thereafter, classifying as a Category 1 on the Saffir–Simpson scale.[9]

As Alex moved north toward the Azores, decreasing sea surface temperatures and increasing wind shear caused the cyclone to weaken through January 14 and 15.[27][28] A deterioration of the convection around the hurricane's eye feature marked the start of its transition back into an extratropical cyclone.[28] Becoming increasingly tilted due to shear,[29] Alex weakened to a tropical storm before making landfall over Terceira Island at 13:15 UTC with winds of 65 mph (100 km/h).[9] Less than five hours later, the system completed its transition into an extratropical cyclone, featuring a more elongated circulation and an expanding radius of maximum winds.[9] Furthermore, the overall structure became more "comma shaped" as a consequence of frontal systems.[30] The system deepened slightly to 978 mbar (hPa; 28.88 inHg) as it turned northwest towards Greenland. On its passage, the cyclone interacted with the mountainous southeastern coast of the island, generating hurricane-force winds over that region. Around 06:00 UTC on January 17, the remnants of Alex were absorbed into a larger extratropical low over the North Atlantic.[9]

Structural evolution of Hurricane Alex from a non-tropical low into a hurricane
  • A non-tropical cyclone with clouds wrapping cyclonically around an open center
    The precursor non-tropical cyclone on January 10
  • A non-tropical cyclone with clouds wrapping cyclonically around an open center; a distinct front can be seen to the southeast of the storm
    The cyclone becomes increasingly separated from frontal boundaries on January 11
  • An area of low pressure with clouds developing atop it
    Convection develops atop the circulation center on January 12, signifying its transition into a subtropical cyclone
  • A cyclone with banding clouds wrapping cyclonically over its center
    Banding features become increasingly defined on January 13 as Alex begins transitioning into a tropical cyclone
  • A well-developed hurricane with a defined, clear eye and prominent clouds surrounding it. A large band of clouds also extends north of the main center
    Alex develops a well-defined eye and core structure — the hallmarks of a hurricane — on January 14

Preparations and impact

Bermuda

The precursor to Alex brought stormy conditions to Bermuda between January 7 and 9.[31] Gusts to 60 mph (97 km/h) on January 8 disrupted air travel, downed trees, and left 753 customers without power. Waves as high as 20 ft (6 m) prompted small craft advisories and the suspension of ferry services between the islands.[13][32][33] The system dropped 1.33 in (34 mm) of rain at Bermuda International Airport over the course of three days.[31]

Azores

A wave crashing against a rocky escarpment
Rough surf from Hurricane Alex on São Miguel Island, in the Azores

When Alex was classified as a hurricane on January 14, the Azores Meteorological Service issued a hurricane warning for the islands of Faial, Pico, São Jorge, Graciosa, and Terceira, and a tropical storm warning for São Miguel and Santa Maria.[34] A red alert—the highest level of weather warnings—was declared for central and eastern islands.[35] Anticipating strong winds and heavy rain, homeowners stacked sandbags to protect their properties from flooding and boarded up doors and windows. Officials closed schools and administrative buildings for the duration of the storm.[7] SATA Air Açores cancelled 33 domestic and international flights for the morning of January 15, stranding more than 700 passengers.[36][37] The hurricane and tropical storm warnings were discontinued on January 15 after Alex had passed.[38]

Traversing the archipelago on January 15, Alex brought heavy rain and gusty winds to several islands.[7] Rainfall totaled 4.04 in (103 mm) in Lagoa, São Miguel,[39] and 3.71 in (94 mm) in Angra do Heroísmo, Terceira.[40] Wind gusts exceeded 50 mph (80 km/h) on Santa Maria Island and peaked at 57 mph (92 km/h) in Ponta Delgada, São Miguel.[10][8] The strong winds brought down trees, damaged some roofs, and triggered scattered power outages. The storm caused minor flooding;[7][41] six homes in Ponta Delgada sustained flood damage, while the winds destroyed the roof of another.[42] Landslides occurred across the central islands, though their damage was limited.[35] Overall, the storm's effects were milder than initially feared,[7] possibly because the strongest winds were located far from the center of Alex as the system underwent extratropical transition.[9] One person suffering a heart attack died as an indirect result of Alex when turbulence from the storm hindered their emergency helicopter from taking off in time.[43][44]

See also

Notes

  1. ^ During winter months, the tropopause lowers in altitude because of the reduced convective activity at higher latitudes. This in turn limits the height of convection that does develop in association with weather systems. During summer months, regular development of thunderstorms pushes this boundary farther up.[19][20]
  2. ^ Typically, sea surface temperatures of at least 80 °F (26.5 °C) are required to provide sufficient energy to fuel thunderstorm development within tropical cyclones.[24] However, analyses of sea surface temperatures and tropical cyclones indicate little to no correlation between this value and cyclogenesis. Other atmospheric factors, as shown in the case of Alex, are the dominant factor in the development of tropical cyclones, especially ones of non-tropical origins in the mid-latitudes.[25][26]

References

  1. ^ Neal Dorst (June 2, 2016). "G1) When is hurricane season ?". Frequently Asked Questions. 4.7. Retrieved August 9, 2019. {{cite book}}: Unknown parameter |agency= ignored (help); Unknown parameter |editors= ignored (|editor= suggested) (help)
  2. ^ National Hurricane Center; Hurricane Research Division (June 4, 2015). "Atlantic hurricane best track (HURDAT)" (Database). 2. United States National Oceanic and Atmospheric Administration. Retrieved January 14, 2016.
  3. ^ a b c d Jeff Masters (January 13, 2016). "Unprecedented: Simultaneous January Named Storms in the Atlantic and Central Pacific". Weather Underground. Archived from the original on January 15, 2016. Retrieved January 14, 2016.
  4. ^ a b Richard Pasch (January 14, 2016). Hurricane Alex Discussion Number 4 (Report). National Hurricane Center. Retrieved January 14, 2016.
  5. ^ Bob Henson (January 15, 2016). "Astounding Alex Hits the Azores: January's First Atlantic Landfall in 61 Years". Weather Underground. Archived from the original on January 16, 2016. Retrieved January 16, 2016.
  6. ^ Mike Carlowicz (January 14, 2016). "An Atlantic Hurricane... in January". National Aeronautics and Space Administration. Retrieved January 17, 2016.
  7. ^ a b c d e Andrei Khalip (January 15, 2016). "Hurricane Alex hits Azores less hard than feared". Reuters. Archived from the original on January 15, 2016. Retrieved January 15, 2016.
  8. ^ a b "Rare January Hurricane Alex Landfalls in The Azores as a Tropical Storm". The Weather Channel. January 15, 2016. Retrieved January 15, 2016.
  9. ^ a b c d e f g h i j k l m n o p q r s Eric S. Blake (September 13, 2016). Hurricane Alex (PDF) (Report). Tropical Cyclone Report. National Hurricane Center. Retrieved September 14, 2016.
  10. ^ a b Scott Bachmeier (January 13, 2016). "Hurricane Alex". CIMSS Satellite Studies. Cooperative Institute for Meteorological Satellite Studies (CIMSS). Retrieved January 17, 2016.
  11. ^ a b Bob Henson (January 7, 2016). "Rare January Depression in Central Pacific; Atlantic Subtropical Storm Next Week?". Weather Underground. Archived from the original on January 8, 2016. Retrieved January 14, 2016.
  12. ^ a b Michael Brennan (January 7, 2016). Special Tropical Weather Outlook (3:25 PM EST – Thu Jan 7, 2016) (.TXT) (Report). Tropical Weather Outlook Atlantic. National Hurricane Center. Retrieved January 14, 2016.
  13. ^ a b Jonathan Bell (January 8, 2016). "Windy weather affects flights and power". The Royal Gazette. Retrieved January 14, 2016.
  14. ^ Jack Beven (January 9, 2016). Special Tropical Weather Outlook (3:00 PM EST – Sat Jan 9, 2016) (.TXT) (Report). Tropical Weather Outlook Atlantic. National Hurricane Center. Retrieved January 14, 2016.
  15. ^ a b Juan Jesús González-Alemán, Jenni L. Evans, and Alex M. Kowaleski (October 2018). "Use of Ensemble Forecasts to Investigate Synoptic Influences on the Structural Evolution and Predictability of Hurricane Alex (2016) in the Midlatitudes". Monthly Weather Review. 146 (10): 3143–3162. Bibcode:2018MWRv..146.3143G. doi:10.1175/MWR-D-18-0015.1.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  16. ^ Michael Brennan (January 10, 2016). Special Tropical Weather Outlook (1:50 PM EST – Sun Jan 10, 2016) (.TXT) (Report). Tropical Weather Outlook Atlantic. National Hurricane Center. Retrieved January 14, 2016.
  17. ^ "[Atlantic Sea Surface Temperature Anomalies for January 10, 2016]" (.PNG). National Oceanic and Atmospheric Administration. Marine Modeling and Analysis Branch. January 10, 2016. Retrieved August 9, 2019.
  18. ^ Richard Pasch (January 11, 2016). Special Tropical Weather Outlook (1:35 PM EST – Mon Jan 11, 2016) (.TXT) (Report). Tropical Weather Outlook Atlantic. National Hurricane Center. Retrieved January 14, 2016.
  19. ^ B. Geerts and E. Linacre (November 1997). "The height of the tropopause". University of Wyoming. Retrieved July 29, 2019.
  20. ^ Günther Zängl and Klaus P. Hoinka (July 2001). "The Tropopause in the Polar Regions". Journal of Climate. 14 (14): 3, 117–3, 139. Bibcode:2001JCli...14.3117Z. doi:10.1175/1520-0442(2001)014<3117:TTITPR>2.0.CO;2.
  21. ^ a b c Richard Pasch (January 13, 2016). Subtropical Storm Alex Discussion Number 1 (Report). National Hurricane Center. Retrieved January 14, 2016.
  22. ^ Jack Beven (January 14, 2016). Subtropical Storm Alex Discussion Number 2 (Report). National Hurricane Center. Retrieved January 14, 2016.
  23. ^ Stacy Stewart (January 14, 2016). Subtropical Storm Alex Discussion Number 3 (Report). National Hurricane Center. Retrieved January 14, 2016.
  24. ^ Chris Landsea (2014). "How do tropical cyclones form ?". Frequently Asked Questions. National Oceanic and Atmospheric Administration. Hurricane Research Division. Retrieved August 9, 2019.
  25. ^ Jenni L. Evans (June 1993). "Sensitivity of Tropical Cyclone Intensity to Sea Surface Temperature". Journal of Climate. 6 (6): 1, 133–1, 140. Bibcode:1993JCli....6.1133E. doi:10.1175/1520-0442(1993)006<1133:SOTCIT>2.0.CO;2. eISSN 1520-0442. ISSN 0894-8755.
  26. ^ Lloyd J. Shapiro and Stanley B. Goldenberg (April 1998). "Atlantic Sea Surface Temperatures and Tropical Cyclone Formation". Journal of Climate. 11 (4): 578–590. Bibcode:1998JCli...11..578S. doi:10.1175/1520-0442(1998)011<0578:ASSTAT>2.0.CO;2. eISSN 1520-0442. ISSN 0894-8755.
  27. ^ Richard Pasch (January 14, 2016). Hurricane Alex Discussion Number 5 (Report). National Hurricane Center. Retrieved January 14, 2016.
  28. ^ a b Jack Beven (January 15, 2016). Hurricane Alex Discussion Number 6 (Report). National Hurricane Center. Retrieved January 15, 2016.
  29. ^ Richard Pasch (January 15, 2016). Tropical Storm Alex Discussion Number 8 (Report). National Hurricane Center. Retrieved January 15, 2016.
  30. ^ Richard Pasch (January 15, 2016). Post-Tropical Cyclone Alex Discussion Number 9 (Report). National Hurricane Center. Retrieved January 15, 2016.
  31. ^ a b "Climate Data: Monthly Climate Report". Bermuda Weather Service. 2016. Retrieved January 14, 2016.
  32. ^ "Windy Conditions Cause Power Outages". Bernews. January 8, 2016. Retrieved August 9, 2019.
  33. ^ "Ferries suspended". The Royal Gazette. January 8, 2016. Retrieved January 14, 2016.
  34. ^ Richard Pasch (January 14, 2016). Hurricane Alex Advisory Number 4 (Advisory). National Hurricane Center. Retrieved January 14, 2016.
  35. ^ a b Ana Dias Cordeiro and Lusa (January 15, 2016). "Furacão Alex passou a tempestade tropical depois de ter atravessado os Açores". Público (in Portuguese). Archived from the original on January 15, 2016. Retrieved January 15, 2016.
  36. ^ "Hurricane Alex Weakens After Passing Azores". The Tribune. Associated Press. January 15, 2016. Retrieved January 15, 2016.
  37. ^ "Pico e São Miguel já sentem o furacão "Alex", mas "nada de monta"". Renascença (in Portuguese). January 15, 2016. Archived from the original on January 17, 2016. Retrieved January 16, 2016.
  38. ^ Richard Pasch (January 15, 2016). Tropical Storm Alex Advisory Number 8 (Report). National Hurricane Center. Retrieved January 15, 2016.
  39. ^ "Lagoa IAZORESL2". Weather Underground. January 15, 2016. Retrieved January 15, 2016.
  40. ^ "Santa Luzia meteo IANGRADO6". Weather Underground. January 15, 2016. Retrieved January 15, 2016.
  41. ^ Sarah Lagan (January 16, 2016). "Residents' fears for families as storm hits". The Royal Gazette. Retrieved January 16, 2016.
  42. ^ "Açores: furacão "Alex" causou 43 ocorrências" (in Portuguese). TVI 24. January 15, 2016. Archived from the original on January 17, 2016. Retrieved January 17, 2016.
  43. ^ Lusa (January 16, 2016). "Furacão Alex impede socorro da Força Aérea e doente morre". Público (in Portuguese). Archived from the original on January 17, 2016. Retrieved January 17, 2016.
  44. ^ Identificação e Avaliação de Impactes, Vulnerabilidades e Opçōes de Adaptação às Alteraçōes Climáticas (PDF) (Report) (in Portuguese). Government of the Azores. October 2017. p. 48. Retrieved July 26, 2019. {{cite report}}: Unknown parameter |agency= ignored (help)
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