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Hurricane Emilia (1994)
Encyclopedia
Hurricane Emilia was the fifth tropical cyclone
, second Pacific hurricane
, and the first major hurricane
of the 1994 Pacific hurricane season. It was the third most intense tropical cyclone in the central Pacific Ocean
, attaining a minimum central pressure
of 926 mbar (27.34 inHg) on July 19—only Gilma and Ioke
reached lower pressures in the basin. It organized to a tropical depression on July 16, quickly attaining tropical storm
intensity. It moved west-northwest
under a ridge
, strengthening to a hurricane on July 17. Subsequently, Emilia underwent rapid deepening
, increasing to a powerful Category 5 hurricane on July 19. In response to an upper-level trough
, Emilia turned northwest on July 21 and encountered wind shear
. The cyclone turned westward and rapidly weakened, dissipating late on July 24.
was detected in the Intertropical Convergence Zone
2110 miles (3,395.7 km) east-southeast of the Hawai’ian chain
. It was traced to a tropical wave
that left the Africa
n coast on June 29. A low-level circulation was present, and a tropical depression is believed to have formed on July 17 due to increasing organization. Later, satellite imagery
suggested that the system had intensified to Tropical Storm Emilia with 40 mph (65 km/h) sustained winds
. Emilia steadily strengthened to a minimal hurricane, moving west-northwest. It crossed 140°W
and entered the Central Pacific Hurricane Center
's area of responsibility, which noted that Emilia was "well developed." Emilia attained winds of 100 mph (160 km/h), which marked the beginning of a rapid intensification period. Maximum sustained winds increased from 115 mph (185 km/h) on July 17 to 160 mph (260 km/h) late on July 19, which was a period of 42 hours. At the time, an Air Force reconnaissance aircraft
measured a minimum central pressure of 926 mbar (27.34 inHg). Although the Central Pacific Hurricane Center lists Emilia as a Category 5 cyclone, the National Hurricane Center
classified Emilia as a strong Category 4 hurricane with 155 mph (250 km/h) sustained winds. However, in 2008, the storm was upgraded to a category 5 hurricane for 6 hours.
On July 20, Emilia briefly weakened to a Category 4 hurricane for 12 hours, but it re-intensified to Category 5 status during the day. Later, Emilia began to weaken for the final time. An upper-level trough in the westerlies
caused the cyclone to turned northwest on July 21, and the threat to Hawai’i increased. Emilia moved over progressively cooler waters, and vertical wind shear
from the westerlies negatively impacted the hurricane. The central pressure
steadily rose to 965 mbar (28.50 inHg), and Emilia diminished to a marginal Category 3 hurricane. On July 22, Emilia continued to weaken, and it passed within 150 nmi (170 miles) of the Big Island
. It was the closest approach to the islands. Later, the peak winds dropped to 75 mph (120 km/h). Emilia gradually turned west-northwest, and the circulation moved with the trade winds. Emilia weakened to a tropical depression on July 24, and a remnant swirl of stratocumulus clouds was noted. The system dissipated on the same day.
Emilia was a Category 5 hurricane for 18 hours, the most ever at the time. That record was broken later in the season by Hurricane John
.
Emilia passed south of the Hawaiian Islands, producing swells of 6–10 feet (2–3.3 m) near the Puna
and Ka‘ū coasts. Surf was lower along the Kona and Kohala coasts. Winds were gusty, causing a few trees to be blown over and branches to be broken. Some minor roof damage was caused by the winds. Rain
fall ranged from light to moderate. All in all, Hurricane Emilia had mostly minor effects in the Hawaiian Islands.
Emilia was the subject of a disagreement between the Central Pacific Hurricane Center
and the National Hurricane Center
. Specifically, they debated Emilia's peak strength in relation to the Saffir-Simpson Hurricane Scale
. The CPHC reported that Emilia's maximum winds peaked at 140 knots (274.4 km/h), making it a Category 5 hurricane. However, the NHC considered Emilia to be a high-end Category 4 with maximum winds of 135 knots (264.6 km/h), in both its "best track" and its preliminary report. During 2008, the NHC upgraded its "best track" to make Emilia a Category 5, although there continues to be a discrepancy in Emilia's duration at Category 5 intensity.
Tropical cyclone
A tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones strengthen when water evaporated from the ocean is released as the saturated air rises, resulting in condensation of water vapor...
, second Pacific hurricane
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...
, and the first major hurricane
Saffir-Simpson Hurricane Scale
The Saffir–Simpson Hurricane Scale , or the Saffir–Simpson Hurricane Wind Scale , classifies hurricanes — Western Hemisphere tropical cyclones that exceed the intensities of tropical depressions and tropical storms — into five categories distinguished by the intensities of their sustained winds...
of the 1994 Pacific hurricane season. It was the third most intense tropical cyclone in the central 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...
, attaining a minimum central pressure
Atmospheric pressure
Atmospheric pressure is the force per unit area exerted into a surface by the weight of air above that surface in the atmosphere of Earth . In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point...
of 926 mbar (27.34 inHg) on July 19—only Gilma and Ioke
Hurricane Ioke
Hurricane Ioke was the strongest hurricane ever recorded in the Central Pacific...
reached lower pressures in the basin. It organized to a tropical depression on July 16, quickly attaining tropical storm
Tropical cyclone scales
Tropical systems are officially ranked on one of several tropical cyclone scales according to their maximum sustained winds and in what oceanic basin they are located...
intensity. It moved west-northwest
Boxing the compass
Boxing the compass is the action of naming all thirty-two points of the compass in clockwise order. Such names are formed by the initials of the cardinal directions and their intermediate ordinal directions, and are very handy to refer to a heading in a general or colloquial fashion, without...
under a ridge
Ridge (meteorology)
A ridge is an elongated region of relatively high atmospheric pressure, the opposite of a trough....
, strengthening to a hurricane on July 17. Subsequently, Emilia underwent rapid deepening
Rapid deepening
Rapid deepening, also known as rapid intensification, is a meteorological condition that occurs when the minimum sea-level atmospheric pressure of a tropical cyclone decreases drastically in a short period of time. The National Weather Service describes rapid deepening as a decrease of...
, increasing to a powerful Category 5 hurricane on July 19. In response to an upper-level trough
Trough (meteorology)
A trough is an elongated region of relatively low atmospheric pressure, often associated with fronts.Unlike fronts, there is not a universal symbol for a trough on a weather chart. The weather charts in some countries or regions mark troughs by a line. In the United States, a trough may be marked...
, Emilia turned northwest on July 21 and encountered 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...
. The cyclone turned westward and rapidly weakened, dissipating late on July 24.
Meteorological history
On July 14, an area of low pressureLow 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...
was detected in the Intertropical Convergence Zone
Intertropical Convergence Zone
The Intertropical Convergence Zone , known by sailors as The Doldrums, is the area encircling the earth near the equator where winds originating in the northern and southern hemispheres come together....
2110 miles (3,395.7 km) east-southeast of the Hawai’ian chain
Hawaiian Islands
The Hawaiian Islands are an archipelago of eight major islands, several atolls, numerous smaller islets, and undersea seamounts in the North Pacific Ocean, extending some 1,500 miles from the island of Hawaii in the south to northernmost Kure Atoll...
. It was traced to a tropical wave
Tropical wave
Tropical waves, easterly waves, or tropical easterly waves, also known as African easterly waves in the Atlantic region, are a type of atmospheric trough, an elongated area of relatively low air pressure, oriented north to south, which move from east to west across the tropics causing areas of...
that left the Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
n coast on June 29. A low-level circulation was present, and a tropical depression is believed to have formed on July 17 due to increasing organization. Later, satellite imagery
Satellite imagery
Satellite imagery consists of photographs of Earth or other planets made by means of artificial satellites.- History :The first images from space were taken on sub-orbital flights. The U.S-launched V-2 flight on October 24, 1946 took one image every 1.5 seconds...
suggested that the system had intensified to Tropical Storm Emilia with 40 mph (65 km/h) sustained winds
Maximum sustained wind
The maximum sustained winds associated with a tropical cyclone are a common indicator of the intensity of the storm. Within a mature tropical cyclone, they are found within the eyewall at a distance defined as the radius of maximum wind, or RMW. Unlike gusts, the value of these winds are...
. Emilia steadily strengthened to a minimal hurricane, moving west-northwest. It crossed 140°W
Longitude
Longitude is a geographic coordinate that specifies the east-west position of a point on the Earth's surface. It is an angular measurement, usually expressed in degrees, minutes and seconds, and denoted by the Greek letter lambda ....
and entered 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...
's area of responsibility, which noted that Emilia was "well developed." Emilia attained winds of 100 mph (160 km/h), which marked the beginning of a rapid intensification period. Maximum sustained winds increased from 115 mph (185 km/h) on July 17 to 160 mph (260 km/h) late on July 19, which was a period of 42 hours. At the time, an Air Force reconnaissance aircraft
Hurricane Hunters
The Hurricane Hunters are aircraft that fly into tropical cyclones in the North Atlantic Ocean and Northeastern Pacific Ocean for the specific purpose of directly measuring weather data in and around those storms. In the United States, the Air Force, Navy, and NOAA units have all participated in...
measured a minimum central pressure of 926 mbar (27.34 inHg). Although the Central Pacific Hurricane Center lists Emilia as a Category 5 cyclone, the National Hurricane Center
National Hurricane Center
The National Hurricane Center , located at Florida International University in Miami, Florida, is the division of the National Weather Service responsible for tracking and predicting weather systems within the tropics between the Prime Meridian and the 140th meridian west poleward to the 30th...
classified Emilia as a strong Category 4 hurricane with 155 mph (250 km/h) sustained winds. However, in 2008, the storm was upgraded to a category 5 hurricane for 6 hours.
On July 20, Emilia briefly weakened to a Category 4 hurricane for 12 hours, but it re-intensified to Category 5 status during the day. Later, Emilia began to weaken for the final time. An upper-level trough in the westerlies
Westerlies
The Westerlies, anti-trades, or Prevailing Westerlies, are the prevailing winds in the middle latitudes between 30 and 60 degrees latitude, blowing from the high pressure area in the horse latitudes towards the poles. These prevailing winds blow from the west to the east, and steer extratropical...
caused the cyclone to turned northwest on July 21, and the threat to Hawai’i increased. Emilia moved over progressively cooler waters, and vertical 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...
from the westerlies negatively impacted the hurricane. The central pressure
Atmospheric pressure
Atmospheric pressure is the force per unit area exerted into a surface by the weight of air above that surface in the atmosphere of Earth . In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point...
steadily rose to 965 mbar (28.50 inHg), and Emilia diminished to a marginal Category 3 hurricane. On July 22, Emilia continued to weaken, and it passed within 150 nmi (170 miles) of the Big Island
Hawaii (island)
The Island of Hawaii, also called the Big Island or Hawaii Island , is a volcanic island in the North Pacific Ocean...
. It was the closest approach to the islands. Later, the peak winds dropped to 75 mph (120 km/h). Emilia gradually turned west-northwest, and the circulation moved with the trade winds. Emilia weakened to a tropical depression on July 24, and a remnant swirl of stratocumulus clouds was noted. The system dissipated on the same day.
Emilia was a Category 5 hurricane for 18 hours, the most ever at the time. That record was broken later in the season by Hurricane John
Hurricane John (1994)
Hurricane John formed during the 1994 Pacific hurricane season and became both the longest-lasting and the farthest-traveling tropical cyclone ever observed...
.
Preparations and impact
Initially, forecasts significantly underestimated the intensification of Emilia, which was one of three tropical cyclones to attain Category 5 status in the central Pacific during the season. On July 16, a 72-hour forecast misjudged the strengthening of Emilia by 41 m/s (92 mph). Later, winds at 72 hours were 31 m/s (69 mph) too high when the cyclone began to weaken. Models consistently predicted Emilia to remain south of the Hawaiian Islands because of the upper troughs' climatologically weak nature during the summer. This led to high confidence in the forecasts, resulting in a lack of watches or warnings.Emilia passed south of the Hawaiian Islands, producing swells of 6–10 feet (2–3.3 m) near the Puna
Puna, Hawaii
Puna is one of the nine districts in Hawaii County, Big Island, Hawaii. The District of Puna is located on the easternmost portion of the island and shares borders to the north with the District of South Hilo and a border to the west with the District of Kaū...
and Ka‘ū coasts. Surf was lower along the Kona and Kohala coasts. Winds were gusty, causing a few trees to be blown over and branches to be broken. Some minor roof damage was caused by the winds. Rain
Rain
Rain is liquid precipitation, as opposed to non-liquid kinds of precipitation such as snow, hail and sleet. Rain requires the presence of a thick layer of the atmosphere to have temperatures above the melting point of water near and above the Earth's surface...
fall ranged from light to moderate. All in all, Hurricane Emilia had mostly minor effects in the Hawaiian Islands.
Emilia was the subject of a disagreement between 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...
and the National Hurricane Center
National Hurricane Center
The National Hurricane Center , located at Florida International University in Miami, Florida, is the division of the National Weather Service responsible for tracking and predicting weather systems within the tropics between the Prime Meridian and the 140th meridian west poleward to the 30th...
. Specifically, they debated Emilia's peak strength in relation to the Saffir-Simpson Hurricane Scale
Saffir-Simpson Hurricane Scale
The Saffir–Simpson Hurricane Scale , or the Saffir–Simpson Hurricane Wind Scale , classifies hurricanes — Western Hemisphere tropical cyclones that exceed the intensities of tropical depressions and tropical storms — into five categories distinguished by the intensities of their sustained winds...
. The CPHC reported that Emilia's maximum winds peaked at 140 knots (274.4 km/h), making it a Category 5 hurricane. However, the NHC considered Emilia to be a high-end Category 4 with maximum winds of 135 knots (264.6 km/h), in both its "best track" and its preliminary report. During 2008, the NHC upgraded its "best track" to make Emilia a Category 5, although there continues to be a discrepancy in Emilia's duration at Category 5 intensity.