Hurricane Emilia (1994)

Infobox Hurricane
Name=Hurricane Emilia (1994)
Type=hurricane
Year=1951
Basin=EPac
Image location=Hurricane Emilia 19 july 1994 1656Z.jpg


Formed=July 16, 1994
Dissipated=July 25, 1994
1-min winds=140
Pressure=926
Da

Inflated=0
Fatalities=None direct
Areas=Hawai’i
Hurricane season=1994 Pacific hurricane season

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.

Meteorological history

On July 14, an area of low pressure was detected in the Intertropical Convergence Zone 2,110 miles (3,400 km) east-southeast of the Hawai’ian chain.cite web|author=Mayfield, Max and Pasch, Richard J.|year=1996|url=http://ams.allenpress.com/archive/1520-0493/124/7/pdf/i1520-0493-124-7-1579.pdf|title=Eastern North Pacific Hurricane Season of 1994|publisher=NOAA|accessdate=2008-02-20|format=PDF] It was traced to a tropical wave that left the African 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.cite web|author=Hurricane Research Division|url=http://www.aoml.noaa.gov/hrd/hurdat/NEpacifichurdat.html|title=Northeast Pacific Best Track Data|publisher=NOAA|accessdate=2008-02-20] 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."cite web|author=Central Pacific Hurricane Center|year=1994|url=http://www.prh.noaa.gov/cphc/summaries/1994.php#Emilia|title=The 1994 Central Pacific Tropical Cyclone Season|publisher=NOAA|accessdate=2008-02-20] 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).cite web|author=Lawrence, Miles|year=1994|url=http://www.nhc.noaa.gov/archive/storm_wallets/epacific/ep1994/emilia/prenhc/prelim01.gif|title=Hurricane Emilia July 16-25 1994|publisher=NOAA|accessdate=2008-02-22] 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.

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.

Preparations

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 Hawai’ian Islands because of the upper troughs' climatologically weak nature during the summer.cite web|url=http://www.nhc.noaa.gov/archive/storm_wallets/epacific/ep1994/emilia/tropdisc/tcd1815z.gif|title=Hurricane Emilia Discussion Number 11|publisher=Central Pacific Hurricane Center|accessdate=2008-02-23] This led to high confidence in the forecasts.cite web|url=http://www.nhc.noaa.gov/archive/storm_wallets/epacific/ep1994/emilia/tropdisc/tcd1903z.gif|title=Hurricane Emilia Discussion Number 13|publisher=Central Pacific Hurricane Center|accessdate=2008-02-23] High confidence in forecasts led to the non-issuing of watches or warnings.

Impact and records

Emilia passed south of the Hawai’ian Islands, producing swells of 6–10 feet (2–3.3 m) near the Puna and Ka‘ū coasts.cite web|author=Lawrence, Miles|year=1994|url=http://www.nhc.noaa.gov/archive/storm_wallets/epacific/ep1994/emilia/prenhc/prelim02.gif|title=Hurricane Emilia Preliminary Report (Page 2)|publisher=NOAA|accessdate=2008-02-23] 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. Rainfall ranged from light to moderate. All in all, Hurricane Emilia had mostly minor effects in the Hawai’ian Islands.

Hurricane Emilia attained Category 5 intensity on July 19, 1994. The previous Category 5 Pacific hurricane, Ava, lost that intensity on June 7, 1973. That is a difference of 7,712 days. The next Category 5 Pacific hurricane, Gilma, attained that intensity on July 24, 1994, four days after Emilia lost it. Emilia hence ended the longest, and began the shortest, spans of time between successive Category 5 Pacific hurricanes. 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.cite web|url=http://www.prh.noaa.gov/cphc/pages/FAQ/Tropical_Cyclone_Records.php#8|title=8. What hurricanes have been at Category Five status the longest?|publisher=Central Pacific Hurricane Center|accessdate=2008-02-23] Emilia was briefly the most intense tropical cyclone on record in the central north Pacific, with a lowest pressure of 926 mbar (hPa). Emilia remains the third most-intense in the central north Pacific, after Gilma and Ioke attained deeper pressures.

Emilia is the subject of a disagreement between the Central Pacific Hurricane Center and the National Hurricane Center. Specifically, they disagree on Emilia's maximum Saffir-Simpson category. The CPHC reports that Emilia's maximum windspeeds were 140 knots, making it a Category 5 hurricane. The NHC disagrees, considering Emilia to be a high-end Category 4 with maximum winds of 135 knots, in both its "best track" and its preliminary report.cite web|author=Lawrence, Miles|year=1994|url=http://www.nhc.noaa.gov/archive/storm_wallets/epacific/ep1994/emilia/prenhc/prelim03.gif|title=Hurricane Emilia Preliminary Report (Page 3)|publisher=NOAA|accessdate=2008-02-23]

References