Tropical Storm Omeka
Encyclopedia
Tropical Storm Omeka was the latest forming Eastern Pacific tropical storm
since reliable records began in 1949. On December 18, 2010, the Central Pacific Hurricane Center
began monitoring a subtropical cyclone
near the International Dateline for possible tropical cyclogenesis
. Over the following two days, the system tracked southwestward, entering the Western Pacific basin
, and began transitioning into a tropical cyclone. Shortly before crossing the dateline on December 20, the CPHC assessed the system to have become a tropical storm. The storm was assigned the name Omeka several hours later as it moved into the Central Pacific basin. Upon doing so, Omeka attained its peak intensity with winds of 50 mph (85 km/h). Shortly thereafter, wind shear
in the region increased, causing the system to weaken. By December 21, the center of Omeka was devoid of convection
and later transitioned into an extratropical cyclone
.
in the western Pacific Ocean
. The storm tracked southeastward near the International Dateline, and by December 18 transitioned into a subtropical cyclone
. A large, sprawling system, little development was initially expected to take place as the storm moved towards the southwest. As the low moved over warmer waters, it was able to maintain an area of deep convection
near its center. According to the CPHC, the system was nearly fully tropical early on December 19 as it moved west of the dateline. However, the Joint Typhoon Warning Center
(JTWC) considered the low to be fully subtropical as a cold-core was present over the center of circulation
. Later on December 19, the Japan Meteorological Agency
(JMA) classified the system as a tropical depression as the low turned towards the southeast. The JTWC estimated the storm attained peak winds of 60 mph (95 km/h) that day. Early on December 20, the JMA issued their final advisory on the depression as it moved east of the dateline and reentered the Central Pacific basin.
Already classifying it as a tropical storm, the Central Pacific Hurricane Center
(CPHC) issued their first advisory on the system at 0900 UTC on December 20, at which time it was situated roughly 505 mi (815 km) south of Midway Island. Upon issuing this advisory, they designated the system as Tropical Storm Omeka, the first named storm of the Central Pacific season. At this time, the storm attained its peak strength with winds of 50 mph (85 km/h) and a barometric pressure of 997 mbar
(hPa
; 29.44 inHg). The storm generally tracked towards the northeast, in response to a mid-level low to the west, throughout the remainder of its existence. Traversing an area of decreased sea surface temperature
s and increasing wind shear
, Omeka quickly weakened to a minimal tropical storm later on December 20. Intermittent bursts of convection
allowed the system to maintain gale-force winds through December 21; however, persistent shear finally took its toll later that morning. Between 0700 and 0800 UTC, Omeka brushed Lisianski Island
with winds of 40 mph (65 km/h). Around 0900 UTC, the CPHC issued their final advisory on Omeka as it transitioned into an extratropical cyclone
roughly 280 mi (450 km) east-southeast of Midway Island. However, in a post-season analysis, it was considered to have remained a tropical depression until dissipating on December 22.
were issued since the CPHC anticipated weakening prior to the storm passing the island. Crossing into the northeast Pacific on December 20, Omeka existed in the northeast Pacific later than any other storm since 1949, when official records begin in the basin. However, according to the CPHC's database, there are two possible tropical cyclones in 1903 and 1904 which developed on December 23. Omeka was the first December storm in the Central Pacific since Tropical Storm Paka
in 1997
. Throughout 2010, the entire Pacific Ocean experienced record-low tropical cyclone activity due to a strong La Niña
. Since Omeka was the first storm in the Central Pacific during the year, it marked the latest start to a season since reliable records began, excluding seasons with no storms.
Pacific hurricane
A Pacific hurricane or tropical storm is a tropical cyclone that develops in the northeastern part of the Pacific Ocean. For organizational purposes, the northern Pacific Ocean is divided into three regions: the eastern, , central , and western...
since reliable records began in 1949. On December 18, 2010, the Central Pacific Hurricane Center
Central Pacific Hurricane Center
The Central Pacific Hurricane Center of the United States National Weather Service is the official body responsible for tracking and issuing tropical cyclone warnings, watches, advisories, discussions, and statements for the Central North Pacific Basin...
began monitoring a subtropical cyclone
Subtropical cyclone
A subtropical cyclone is a weather system that has some characteristics of a tropical and an extratropical cyclone. As early as the 1950s, meteorologists were unclear whether they should be characterized as tropical or extratropical cyclones. They were officially recognized by the National...
near the International Dateline for possible tropical cyclogenesis
Tropical cyclogenesis
Tropical cyclogenesis is the term that describes the development and strengthening of a tropical cyclone in the atmosphere. The mechanisms through which tropical cyclogenesis occurs are distinctly different from those through which mid-latitude cyclogenesis occurs...
. Over the following two days, the system tracked southwestward, entering the Western Pacific basin
Pacific typhoon
A typhoon is a mature tropical cyclone that develops in the northwestern part of the Pacific Ocean between 180° and 100°E. This region is referred to as the northwest Pacific basin. For organizational purposes, the northern Pacific Ocean is divided into three regions: the eastern , central , and...
, and began transitioning into a tropical cyclone. Shortly before crossing the dateline on December 20, the CPHC assessed the system to have become a tropical storm. The storm was assigned the name Omeka several hours later as it moved into the Central Pacific basin. Upon doing so, Omeka attained its peak intensity with winds of 50 mph (85 km/h). Shortly thereafter, wind shear
Wind shear
Wind shear, sometimes referred to as windshear or wind gradient, is a difference in wind speed and direction over a relatively short distance in the atmosphere...
in the region increased, causing the system to weaken. By December 21, the center of Omeka was devoid of convection
Atmospheric convection
Atmospheric convection is the result of a parcel-environment instability, or temperature difference, layer in the atmosphere. Different lapse rates within dry and moist air lead to instability. Mixing of air during the day which expands the height of the planetary boundary layer leads to...
and later transitioned into an extratropical cyclone
Extratropical cyclone
Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are a group of cyclones defined as synoptic scale low pressure weather systems that occur in the middle latitudes of the Earth having neither tropical nor polar characteristics, and are connected with fronts and...
.
Meteorological history
The origins of Omeka were from an extratropical cycloneExtratropical cyclone
Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are a group of cyclones defined as synoptic scale low pressure weather systems that occur in the middle latitudes of the Earth having neither tropical nor polar characteristics, and are connected with fronts and...
in the western Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
. The storm tracked southeastward near the International Dateline, and by December 18 transitioned into a subtropical cyclone
Subtropical cyclone
A subtropical cyclone is a weather system that has some characteristics of a tropical and an extratropical cyclone. As early as the 1950s, meteorologists were unclear whether they should be characterized as tropical or extratropical cyclones. They were officially recognized by the National...
. A large, sprawling system, little development was initially expected to take place as the storm moved towards the southwest. As the low moved over warmer waters, it was able to maintain an area of deep convection
Atmospheric convection
Atmospheric convection is the result of a parcel-environment instability, or temperature difference, layer in the atmosphere. Different lapse rates within dry and moist air lead to instability. Mixing of air during the day which expands the height of the planetary boundary layer leads to...
near its center. According to the CPHC, the system was nearly fully tropical early on December 19 as it moved west of the dateline. However, the Joint Typhoon Warning Center
Joint Typhoon Warning Center
The Joint Typhoon Warning Center is a joint United States Navy – United States Air Force task force located at the Naval Maritime Forecast Center in Pearl Harbor, Hawaii...
(JTWC) considered the low to be fully subtropical as a cold-core was present over the center of circulation
Low pressure area
A low-pressure area, or "low", is a region where the atmospheric pressure at sea level is below that of surrounding locations. Low-pressure systems form under areas of wind divergence which occur in upper levels of the troposphere. The formation process of a low-pressure area is known as...
. Later on December 19, the Japan Meteorological Agency
Japan Meteorological Agency
The or JMA, is the Japanese government's weather service. Charged with gathering and reporting weather data and forecasts in Japan, it is a semi-autonomous part of the Ministry of Land, Infrastructure and Transport...
(JMA) classified the system as a tropical depression as the low turned towards the southeast. The JTWC estimated the storm attained peak winds of 60 mph (95 km/h) that day. Early on December 20, the JMA issued their final advisory on the depression as it moved east of the dateline and reentered the Central Pacific basin.
Already classifying it as a tropical storm, the Central Pacific Hurricane Center
Central Pacific Hurricane Center
The Central Pacific Hurricane Center of the United States National Weather Service is the official body responsible for tracking and issuing tropical cyclone warnings, watches, advisories, discussions, and statements for the Central North Pacific Basin...
(CPHC) issued their first advisory on the system at 0900 UTC on December 20, at which time it was situated roughly 505 mi (815 km) south of Midway Island. Upon issuing this advisory, they designated the system as Tropical Storm Omeka, the first named storm of the Central Pacific season. At this time, the storm attained its peak strength with winds of 50 mph (85 km/h) and a barometric pressure of 997 mbar
Bar (unit)
The bar is a unit of pressure equal to 100 kilopascals, and roughly equal to the atmospheric pressure on Earth at sea level. Other units derived from the bar are the megabar , kilobar , decibar , centibar , and millibar...
(hPa
Pascal (unit)
The pascal is the SI derived unit of pressure, internal pressure, stress, Young's modulus and tensile strength, named after the French mathematician, physicist, inventor, writer, and philosopher Blaise Pascal. It is a measure of force per unit area, defined as one newton per square metre...
; 29.44 inHg). The storm generally tracked towards the northeast, in response to a mid-level low to the west, throughout the remainder of its existence. Traversing an area of decreased sea surface temperature
Sea surface temperature
Sea surface temperature is the water temperature close to the oceans surface. The exact meaning of surface varies according to the measurement method used, but it is between and below the sea surface. Air masses in the Earth's atmosphere are highly modified by sea surface temperatures within a...
s and increasing wind shear
Wind shear
Wind shear, sometimes referred to as windshear or wind gradient, is a difference in wind speed and direction over a relatively short distance in the atmosphere...
, Omeka quickly weakened to a minimal tropical storm later on December 20. Intermittent bursts of convection
Atmospheric convection
Atmospheric convection is the result of a parcel-environment instability, or temperature difference, layer in the atmosphere. Different lapse rates within dry and moist air lead to instability. Mixing of air during the day which expands the height of the planetary boundary layer leads to...
allowed the system to maintain gale-force winds through December 21; however, persistent shear finally took its toll later that morning. Between 0700 and 0800 UTC, Omeka brushed Lisianski Island
Lisianski Island
Lisianski Island is one of the Northwestern Hawaiian Islands, with a land area of and a maximum elevation of above sea level. Honolulu is away, to the southeast. Linked to Lisianski are the extensive Neva Shoals...
with winds of 40 mph (65 km/h). Around 0900 UTC, the CPHC issued their final advisory on Omeka as it transitioned into an extratropical cyclone
Extratropical cyclone
Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are a group of cyclones defined as synoptic scale low pressure weather systems that occur in the middle latitudes of the Earth having neither tropical nor polar characteristics, and are connected with fronts and...
roughly 280 mi (450 km) east-southeast of Midway Island. However, in a post-season analysis, it was considered to have remained a tropical depression until dissipating on December 22.
Impact and records
On December 21, the center of Omeka brushed Lisianski Island, likely bringing tropical storm-force winds to the island. However, no tropical storm watches or warningsTropical cyclone warnings and watches
Warnings and watches are two levels of alert issued by national weather forecasting bodies to coastal areas threatened by the imminent approach of a tropical cyclone of tropical storm or hurricane intensity. They are notices to the local population and civil authorities to make appropriate...
were issued since the CPHC anticipated weakening prior to the storm passing the island. Crossing into the northeast Pacific on December 20, Omeka existed in the northeast Pacific later than any other storm since 1949, when official records begin in the basin. However, according to the CPHC's database, there are two possible tropical cyclones in 1903 and 1904 which developed on December 23. Omeka was the first December storm in the Central Pacific since Tropical Storm Paka
Typhoon Paka
Typhoon Paka was the last tropical cyclone in the 1997 Pacific Ocean hurricane and typhoon season, and was among the strongest Pacific typhoons in the month of December. Paka, which is the Hawaiian name for Pat, developed on November 28 from a trough well to the southwest of Hawaii...
in 1997
1997 Pacific hurricane season
The 1997 Pacific hurricane season was a very active hurricane season. With hundreds of deaths and billions of dollars in damage, this season was the costliest and one of the deadliest Pacific hurricane seasons. This was due to a strong El Niño...
. Throughout 2010, the entire Pacific Ocean experienced record-low tropical cyclone activity due to a strong La Niña
La Niña
La Niña is a coupled ocean-atmosphere phenomenon that is the counterpart of El Niño as part of the broader El Niño-Southern Oscillation climate pattern. During a period of La Niña, the sea surface temperature across the equatorial Eastern Central Pacific Ocean will be lower than normal by 3–5 °C...
. Since Omeka was the first storm in the Central Pacific during the year, it marked the latest start to a season since reliable records began, excluding seasons with no storms.