Hurricane Pali was the earliest-forming
Pacific hurricane on record, being the first Pacific hurricane to occur in January since
Hurricane Ekeka of
1992. The first
tropical cyclone of the
2016 Pacific hurricane season, Pali originated as an
area of low pressure within a persistent
trough, near the
equator on January 6, 2016. Deep
convection gradually built up around the center of the disturbance as the system curved northward, before it organized into a tropical depression on the next day, making the system the earliest recorded
tropical cyclone in the Pacific hurricane basin. The system quickly intensified into a
tropical storm, resulting in it being named Pali. During the next few days, Pali slowly moved northward while slowly curving towards the west, strengthening somewhat before weakening due to the presence of wind shear. On January 10, Pali slowly turned eastward and proceeded to re-strengthen as wind shear diminished.
On January 12, Pali strengthened into a
Category1 hurricane on the
Saffir–Simpson scale (SSWHS) while curving towards the south. The next day, Pali reached its peak intensity as a Category 2 hurricane, with 1-minute
maximum sustained winds of 100mph (155km/h)[nb 1] and a
minimum central pressure of 978mbar (
hPa; 28.88inHg). Afterward, Pali quickly began to weaken, as the storm encountered stronger wind shear, with the storm weakening into a Category 1 hurricane several hours later, before weakening into a tropical storm later that day. On January 14, Pali weakened into a tropical depression before degenerating into a remnant low the next day, since conditions became increasingly hostile. Later that day, Pali's remnants dissipated near the same location where they had formed roughly a week ago. Pali formed and tracked near the equator, forming at a latitude of 3.3°N and tracking as low as 2.6°N as a tropical depression. This made Pali the second-lowest latitude tropical cyclone on record in the
Western Hemisphere at the time, which was extremely unusual, given the
unfavorable conditions that are usually in place around the equator.
Pali had severe impacts in
Kiribati, grounding a cargo ship and killing four people, in addition to causing major
coastal flooding, although the total amount of damage was not specified in the island nation's report to the
World Meteorological Organisation (WMO).[2][3][4]
Background and records
As currently defined, the
Pacific hurricane season lasts from May 15 to November 30, the period in which tropical cyclones are most likely to develop across the basin. Occasionally, systems
develop outside these seasons,[5] most frequently in May or December, though some off-season storms also develop in January.[6] Activity in January is extremely rare; only two systems other than Pali have been recorded since 1949:
Tropical Storm Winona in 1989 and
Hurricane Ekeka in 1992, which became a
Category 3 major hurricane.[7][6] Pali was the earliest tropical cyclone recorded in the Central Pacific basin, forming on January 7, beating Tropical Storm Winona by six days.[8] Pali was also the earliest recorded Central Pacific hurricane, reaching hurricane intensity on January 12, beating the previous record-holder, Hurricane Ekeka, by 19 days.[9]
Pali also formed and tracked closer to the equator than any other storm recorded in the Pacific hurricane basin.[9][10] Pali became a tropical depression near
3.3°N.[1] During its final days as a tropical cyclone, Pali reached a minimum latitude of
2.6°N as a tropical depression, making it the second-lowest latitude tropical cyclone on record in the Western Hemisphere, just behind
Tropical Depression Nine-C, which attained a minimum latitude of 2.2°N just two weeks prior;[1][11][12] no other tropical cyclone in the
National Oceanic and Atmospheric Administration (NOAA)'s records in the Central Pacific had ever ventured that close to the equator, dating back to 1842.[9] Tropical cyclones usually do not develop that close to the equator, due to the strength of the
Coriolis force at those
latitudes, which is too weak to induce the spin necessary to form tropical cyclones.[9][7] Prior to the storm's dissipation, when Pali curved back towards the south, some meteorologists speculated that Pali could cross over the equator into the
Southern Hemisphere, given the steering currents in place, which would have been an extremely rare occurrence had the storm done so.[9][13]
Unrelated to Pali, the formation of
Hurricane Alex over the
North Atlantic in mid-January coincided with Pali's development over the Central Pacific. This marked the first occurrence of simultaneous January tropical cyclones between these two basins.[14]
Meteorological history
In late December 2015, a long-lived and powerful
westerly wind burst—a feature commonly associated with strong
El Niño events—triggered the formation of
Tropical Depression Nine-C in the central North Pacific, along with its twin,
Tropical Cyclone Ula, in the
central South Pacific. Tropical Depression Nine-C quickly dissipated by the start of 2016, leaving behind a large area of moisture across the equatorial Pacific.[1][11][12] The persistent, powerful westerly wind burst spurred
cyclogenesis within a persistent, low-latitude, west-to-east-oriented surface trough that spanned between
1.0°N and
3.0°N latitude as far east as
155.0°W longitude, resulting in the formation of a weak
area of low pressure on January 6, at the extremely low latitude of
1.9°N.[1] The disturbance developed in an area of high
wind shear, which kept the system from quickly organizing. The low and the trough drifted northward, as the
subtropicalridge spanning the region was significantly weakened by a passing
extratropical storm in the North Pacific. Deep
convection then developed near the low and also along a broad portion of the trough; however,
thunderstorms failed to concentrate around the center of the disturbance. Fueled by unusually high
sea surface temperatures, estimated at 29.5 °C (85.1 °F), deep convection increased and gradually organized around the low, and the system gradually coalesced into a tropical depression by 06:00 UTC on January 7, at a latitude of 3.3°N. This marked the earliest formation of a tropical cyclone on record in the Central Pacific, surpassing
1989's Tropical Storm Winona by six days.[8] A ridge aloft centered directly above the system enhanced its poleward
anticyclonicoutflow, enabling the development of deep convection around its center, and soon afterward, the system strengthened into a tropical storm, which received the name Pali, becoming the earliest tropical cyclone recorded in the northeastern Pacific.[1][15]
Pali continued intensifying through the first half of January 8 and nearly reached Category 1 hurricane strength, with maximum 1-minute sustained winds reaching 70 mph (110 km/h), but easterly vertical wind shear caused by the ridge aloft increased and disrupted its center, causing the storm to start weakening and curve northwestward.[1] Steady weakening continued through January 9, as Pali's deep convection was displaced to the west of its low-level circulation center and intermittently pulsed, later leading to a sharp decrease in the storm's intensity.[1] By the end of that day, Pali barely maintained tropical storm strength, with the storm's 1-minute sustained winds registering at 40 mph (65 km/h). The lack of persistent deep convection resulted in Pali being a weaker system, but this permitted the storm to be more resistant to the easterly wind shear, causing its forward motion to decrease significantly.[1] The ridge of high pressure weakened and retreated southward on January 10, which caused the vertical wind shear to gradually diminish. Afterward, Pali started re-intensifying, with persistent deep convection redeveloping near its center and within the storm's western quadrant. This shift in steering currents also caused Pali to slowly turn eastward. Pali almost completely stalled during this time, due to the absence of significant steering currents.[1] On January 11, the ridge of high pressure moved directly over Pali, leading to the reestablishment of poleward outflow above the storm and the eventual development of southwesterly flow aloft, enabling the storm's convection to slowly increase in coverage and organization within all quadrants, and also establishing a northeastward movement.[1] At 00:00 UTC on January 12, light vertical wind shear and high sea surface temperatures enabled Pali to strengthen into a Category 1 hurricane, becoming the earliest hurricane on record in the northeast Pacific basin, beating the previous record set by
Hurricane Ekeka in 1992, by 19 days. Around the same time, the storm began curving towards the southeast, as a deep ridge developed to the north. The storm also displayed a well-defined
eye by 18:00 UTC that day.[1] Pali continued strengthening while travelling southward, and early on January 13, Pali reached its peak intensity as a
Category 2 hurricane, with maximum 1-minute sustained winds of 100 mph (155 km/h) and a minimum central pressure of 978 millibars (28.9 inHg).[1][16]
During the next few days, Pali rapidly weakened while turning back towards the south-southwest, due to steady increases in southerly vertical wind shear and the loss of Coriolis force. The storm's weakening trend began on January 13 and accelerated through the next day, as Pali moved back towards the area from where it had formed. The storm's eye became indistinguishable by 06:00 UTC on January 13, as the system continued to weaken.[1] Vertical wind shear exceeded 25 mph (40 km/h) by early January 14. Further decay in the organization of the storm's deep convection caused Pali to be downgraded into a remnant low late on January 14, with the system barely being distinguishable within the surface trough where it had spent its entire life,[1][17] and the storm's center dissipated by 00:00 UTC on January 15. However, Pali's remnants continued to persist for a while, before dissipating later that day.[18][19] Pali completed a broad and looping track, dissipating approximately 50 nmi (58 mi; 93 km) from where it had initially developed.[1] While weakening, Pali reached a minimum latitude of 2.6°N, making it the second-lowest latitude tropical cyclone on record in the Western Hemisphere, behind Tropical Depression Nine-C, which attained a minimum latitude of 2.2°N just two weeks prior.[1][11][12]
Structural evolution of Hurricane Pali from a tropical disturbance into a hurricane
The precursor disturbance on January 6. Note organization of thunderstorms around the center of the storm.
A low-level circulation develops, convection wraps around the center, and winds increase to tropical storm-force, signifying the system's development into a tropical storm.
Convection concentrates around the center of circulation and increases, indicating the storm's strengthening trend
Banding features become increasingly defined, and an eye appears, signifying the storm's intensification into a hurricane
The storm peaks as a Category 2 hurricane, with a small, distinct eye visible in the center of the storm
Impacts
In the 19th session of the
World Meteorological Organisation (WMO)'s Tropical Cyclone Committee, in July 2021, Kiribati reported that Hurricane Pali had severe impacts in Kiribati. While Pali caused a significant amount of property damage, the exact amount of damage was not given in the report to the WMO.[2] Pali caused a cargo ship to run aground on the coast of Kiribati, killing four people.[3] Additionally, Pali's
storm surge combined with the
Spring Tide and the El Niño-induced above-average sea level, producing major coastal flooding in Kiribati, which caused significant damage to the island nation's coastal infrastructure.[4][20]
^
abNational Hurricane Center; Hurricane Research Division (May 26, 2020).
"Pacific hurricane best track (HURDAT)" (Database). 2. United States National Oceanic and Atmospheric Administration.
Archived from the original on March 19, 2021. Retrieved March 24, 2021.
Hurricane Pali was the earliest-forming
Pacific hurricane on record, being the first Pacific hurricane to occur in January since
Hurricane Ekeka of
1992. The first
tropical cyclone of the
2016 Pacific hurricane season, Pali originated as an
area of low pressure within a persistent
trough, near the
equator on January 6, 2016. Deep
convection gradually built up around the center of the disturbance as the system curved northward, before it organized into a tropical depression on the next day, making the system the earliest recorded
tropical cyclone in the Pacific hurricane basin. The system quickly intensified into a
tropical storm, resulting in it being named Pali. During the next few days, Pali slowly moved northward while slowly curving towards the west, strengthening somewhat before weakening due to the presence of wind shear. On January 10, Pali slowly turned eastward and proceeded to re-strengthen as wind shear diminished.
On January 12, Pali strengthened into a
Category1 hurricane on the
Saffir–Simpson scale (SSWHS) while curving towards the south. The next day, Pali reached its peak intensity as a Category 2 hurricane, with 1-minute
maximum sustained winds of 100mph (155km/h)[nb 1] and a
minimum central pressure of 978mbar (
hPa; 28.88inHg). Afterward, Pali quickly began to weaken, as the storm encountered stronger wind shear, with the storm weakening into a Category 1 hurricane several hours later, before weakening into a tropical storm later that day. On January 14, Pali weakened into a tropical depression before degenerating into a remnant low the next day, since conditions became increasingly hostile. Later that day, Pali's remnants dissipated near the same location where they had formed roughly a week ago. Pali formed and tracked near the equator, forming at a latitude of 3.3°N and tracking as low as 2.6°N as a tropical depression. This made Pali the second-lowest latitude tropical cyclone on record in the
Western Hemisphere at the time, which was extremely unusual, given the
unfavorable conditions that are usually in place around the equator.
Pali had severe impacts in
Kiribati, grounding a cargo ship and killing four people, in addition to causing major
coastal flooding, although the total amount of damage was not specified in the island nation's report to the
World Meteorological Organisation (WMO).[2][3][4]
Background and records
As currently defined, the
Pacific hurricane season lasts from May 15 to November 30, the period in which tropical cyclones are most likely to develop across the basin. Occasionally, systems
develop outside these seasons,[5] most frequently in May or December, though some off-season storms also develop in January.[6] Activity in January is extremely rare; only two systems other than Pali have been recorded since 1949:
Tropical Storm Winona in 1989 and
Hurricane Ekeka in 1992, which became a
Category 3 major hurricane.[7][6] Pali was the earliest tropical cyclone recorded in the Central Pacific basin, forming on January 7, beating Tropical Storm Winona by six days.[8] Pali was also the earliest recorded Central Pacific hurricane, reaching hurricane intensity on January 12, beating the previous record-holder, Hurricane Ekeka, by 19 days.[9]
Pali also formed and tracked closer to the equator than any other storm recorded in the Pacific hurricane basin.[9][10] Pali became a tropical depression near
3.3°N.[1] During its final days as a tropical cyclone, Pali reached a minimum latitude of
2.6°N as a tropical depression, making it the second-lowest latitude tropical cyclone on record in the Western Hemisphere, just behind
Tropical Depression Nine-C, which attained a minimum latitude of 2.2°N just two weeks prior;[1][11][12] no other tropical cyclone in the
National Oceanic and Atmospheric Administration (NOAA)'s records in the Central Pacific had ever ventured that close to the equator, dating back to 1842.[9] Tropical cyclones usually do not develop that close to the equator, due to the strength of the
Coriolis force at those
latitudes, which is too weak to induce the spin necessary to form tropical cyclones.[9][7] Prior to the storm's dissipation, when Pali curved back towards the south, some meteorologists speculated that Pali could cross over the equator into the
Southern Hemisphere, given the steering currents in place, which would have been an extremely rare occurrence had the storm done so.[9][13]
Unrelated to Pali, the formation of
Hurricane Alex over the
North Atlantic in mid-January coincided with Pali's development over the Central Pacific. This marked the first occurrence of simultaneous January tropical cyclones between these two basins.[14]
Meteorological history
In late December 2015, a long-lived and powerful
westerly wind burst—a feature commonly associated with strong
El Niño events—triggered the formation of
Tropical Depression Nine-C in the central North Pacific, along with its twin,
Tropical Cyclone Ula, in the
central South Pacific. Tropical Depression Nine-C quickly dissipated by the start of 2016, leaving behind a large area of moisture across the equatorial Pacific.[1][11][12] The persistent, powerful westerly wind burst spurred
cyclogenesis within a persistent, low-latitude, west-to-east-oriented surface trough that spanned between
1.0°N and
3.0°N latitude as far east as
155.0°W longitude, resulting in the formation of a weak
area of low pressure on January 6, at the extremely low latitude of
1.9°N.[1] The disturbance developed in an area of high
wind shear, which kept the system from quickly organizing. The low and the trough drifted northward, as the
subtropicalridge spanning the region was significantly weakened by a passing
extratropical storm in the North Pacific. Deep
convection then developed near the low and also along a broad portion of the trough; however,
thunderstorms failed to concentrate around the center of the disturbance. Fueled by unusually high
sea surface temperatures, estimated at 29.5 °C (85.1 °F), deep convection increased and gradually organized around the low, and the system gradually coalesced into a tropical depression by 06:00 UTC on January 7, at a latitude of 3.3°N. This marked the earliest formation of a tropical cyclone on record in the Central Pacific, surpassing
1989's Tropical Storm Winona by six days.[8] A ridge aloft centered directly above the system enhanced its poleward
anticyclonicoutflow, enabling the development of deep convection around its center, and soon afterward, the system strengthened into a tropical storm, which received the name Pali, becoming the earliest tropical cyclone recorded in the northeastern Pacific.[1][15]
Pali continued intensifying through the first half of January 8 and nearly reached Category 1 hurricane strength, with maximum 1-minute sustained winds reaching 70 mph (110 km/h), but easterly vertical wind shear caused by the ridge aloft increased and disrupted its center, causing the storm to start weakening and curve northwestward.[1] Steady weakening continued through January 9, as Pali's deep convection was displaced to the west of its low-level circulation center and intermittently pulsed, later leading to a sharp decrease in the storm's intensity.[1] By the end of that day, Pali barely maintained tropical storm strength, with the storm's 1-minute sustained winds registering at 40 mph (65 km/h). The lack of persistent deep convection resulted in Pali being a weaker system, but this permitted the storm to be more resistant to the easterly wind shear, causing its forward motion to decrease significantly.[1] The ridge of high pressure weakened and retreated southward on January 10, which caused the vertical wind shear to gradually diminish. Afterward, Pali started re-intensifying, with persistent deep convection redeveloping near its center and within the storm's western quadrant. This shift in steering currents also caused Pali to slowly turn eastward. Pali almost completely stalled during this time, due to the absence of significant steering currents.[1] On January 11, the ridge of high pressure moved directly over Pali, leading to the reestablishment of poleward outflow above the storm and the eventual development of southwesterly flow aloft, enabling the storm's convection to slowly increase in coverage and organization within all quadrants, and also establishing a northeastward movement.[1] At 00:00 UTC on January 12, light vertical wind shear and high sea surface temperatures enabled Pali to strengthen into a Category 1 hurricane, becoming the earliest hurricane on record in the northeast Pacific basin, beating the previous record set by
Hurricane Ekeka in 1992, by 19 days. Around the same time, the storm began curving towards the southeast, as a deep ridge developed to the north. The storm also displayed a well-defined
eye by 18:00 UTC that day.[1] Pali continued strengthening while travelling southward, and early on January 13, Pali reached its peak intensity as a
Category 2 hurricane, with maximum 1-minute sustained winds of 100 mph (155 km/h) and a minimum central pressure of 978 millibars (28.9 inHg).[1][16]
During the next few days, Pali rapidly weakened while turning back towards the south-southwest, due to steady increases in southerly vertical wind shear and the loss of Coriolis force. The storm's weakening trend began on January 13 and accelerated through the next day, as Pali moved back towards the area from where it had formed. The storm's eye became indistinguishable by 06:00 UTC on January 13, as the system continued to weaken.[1] Vertical wind shear exceeded 25 mph (40 km/h) by early January 14. Further decay in the organization of the storm's deep convection caused Pali to be downgraded into a remnant low late on January 14, with the system barely being distinguishable within the surface trough where it had spent its entire life,[1][17] and the storm's center dissipated by 00:00 UTC on January 15. However, Pali's remnants continued to persist for a while, before dissipating later that day.[18][19] Pali completed a broad and looping track, dissipating approximately 50 nmi (58 mi; 93 km) from where it had initially developed.[1] While weakening, Pali reached a minimum latitude of 2.6°N, making it the second-lowest latitude tropical cyclone on record in the Western Hemisphere, behind Tropical Depression Nine-C, which attained a minimum latitude of 2.2°N just two weeks prior.[1][11][12]
Structural evolution of Hurricane Pali from a tropical disturbance into a hurricane
The precursor disturbance on January 6. Note organization of thunderstorms around the center of the storm.
A low-level circulation develops, convection wraps around the center, and winds increase to tropical storm-force, signifying the system's development into a tropical storm.
Convection concentrates around the center of circulation and increases, indicating the storm's strengthening trend
Banding features become increasingly defined, and an eye appears, signifying the storm's intensification into a hurricane
The storm peaks as a Category 2 hurricane, with a small, distinct eye visible in the center of the storm
Impacts
In the 19th session of the
World Meteorological Organisation (WMO)'s Tropical Cyclone Committee, in July 2021, Kiribati reported that Hurricane Pali had severe impacts in Kiribati. While Pali caused a significant amount of property damage, the exact amount of damage was not given in the report to the WMO.[2] Pali caused a cargo ship to run aground on the coast of Kiribati, killing four people.[3] Additionally, Pali's
storm surge combined with the
Spring Tide and the El Niño-induced above-average sea level, producing major coastal flooding in Kiribati, which caused significant damage to the island nation's coastal infrastructure.[4][20]
^
abNational Hurricane Center; Hurricane Research Division (May 26, 2020).
"Pacific hurricane best track (HURDAT)" (Database). 2. United States National Oceanic and Atmospheric Administration.
Archived from the original on March 19, 2021. Retrieved March 24, 2021.