Hurricane Emilia (1994)

Map plotting the track and the intensity of the storm, according to the Saffir–Simpson scale

On June 29, a weak tropical wave exited the west African coast and traversed the Atlantic, showing no signs of organization or convective activity. Moving within the Intertropical Convergence Zone, the tropical disturbance remained inactive until July 14, when it developed into an area of low pressure roughly 2,110 mi (3,400 km) east-southeast of the Hawaiian Islands. A low-level circulation became evident, and the system was designated as a tropical depression on July 16. Within 12 hours, satellite imagery suggested that the system had intensified into Tropical Storm Emilia with 40 mph (64 km/h) sustained winds.[1][2] Emilia steadily intensified into a minimal hurricane by the next morning, as it moved west-northwest.[2] At 18:00 UTC, Emilia was upgraded to Category 2 status as it crossed 140°W and entered the Central Pacific Hurricane Center's (CPHC) area of responsibility, which noted that Emilia was "well developed."[3] Emilia then proceeded to rapidly intensify, with maximum sustained winds increasing from 105 to 160 mph (169 to 257 km/h) over the next 48 hours.[2][3] At Emilia's peak strength, an Air Force reconnaissance aircraft measured a minimum central pressure of 926 mbar (27.34 inHg), the lowest pressure ever recorded in a Central Pacific hurricane at that time.[4][nb 1]

Oblique view from orbit

On July 20, Emilia briefly weakened into a Category 4 hurricane, but it was re-upgraded to Category 5 status by the CPHC 12 hours later during the day.[3] Subsequently, Emilia began to weaken for the final time. An upper-level trough in the westerlies caused the cyclone to turn northwest on July 21.[3][4] Emilia moved over progressively cooler waters, and vertical wind shear from the westerlies negatively impacted the hurricane.[3] The central pressure steadily rose to 965 mbar (28.50 inHg), and Emilia diminished into a marginal Category 3 hurricane.[3] On July 22, Emilia continued to weaken, and it passed within 170 mi (270 km) of the Big Island.[4] It was the closest approach to the islands.[4] Later, Emilia's peak winds dropped to 75 mph (121 km/h).[3] Emilia gradually turned west-northwest, and the circulation moved with the trade winds.[4] Emilia weakened into a tropical depression on July 24,[3] and a remnant swirl of stratocumulus clouds was noted.[4] The system dissipated on the same day.[3][5]

Initially, forecasts significantly underestimated the intensification of Emilia,[1] which was one of three tropical cyclones to attain Category 5 status in the central Pacific during the season.[3] On July 16, a 72-hour forecast misjudged the strengthening of Emilia by 41 m/s (92 mph).[1] Later, winds at 72 hours were 31 m/s (69 mph) too high when the cyclone began to weaken.[1] Tropical cyclone forecast models consistently predicted Emilia to remain south of the Hawaiian Islands because of the upper troughs' climatologically weak nature during the summer.[6] This led to high confidence in the forecasts,[7] resulting in a lack of watches or warnings.[3] Nonetheless, a high surf advisory was issued for the south and east coasts of all islands.[8]

Emilia passing to the south of Hawaii on July 22

Despite the storm's offshore nature, swells of 6–10 feet (1.8–3.0 metres) were reported near the Puna and Ka‘ū coasts.[9] Waikiki Beach in Honolulu reported a 5 ft (1.5 m) high surf. Surf was lower along the Kona and Kohala coasts.[3][10] 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.[3] International observatories and the Keck Telescope on the top of Mauna Kea were forced to close their domes due to the high winds.[11] Rainfall ranged from light to moderate. The storm passed near two National Oceanic and Atmospheric Administration (NOAA) weather buoys during its passage through the state. All in all, Hurricane Emilia had mostly minor effects in the Hawaiian Islands.[3]

Emilia is one of the most intense tropical cyclones on record in the Eastern Pacific, with a minimum pressure of 926 mbar (hPa; 27.34 inHg). In the CPHC warning zone, only Gilma, Ioke of 2006, and hurricanes Lane and Walaka of 2018 attained deeper pressures.[2] Emilia was also a Category 5 hurricane for 18 hours, the most ever at the time in the Central Pacific. That record was broken later in the season by Hurricane John.[12]

The storm 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 (SSHWS). The CPHC reported that Emilia's maximum winds peaked at 140 knots (260 km/h), making it a Category 5 hurricane.[3] However, the NHC considered Emilia to be a high-end Category 4 with maximum winds of 135 knots (250 km/h), in both its "best track"[13] and its preliminary report.[14] 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. The CPHC's data deems Emilia as having regained Category 5 status at 18:00 UTC July 20 and maintaining it for 12 hours, while the NHC's data places Emilia as having maintained Category 4-strength winds of 155 mph (249 km/h) during this period.[2][3]

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• Other storms of the same name
• Hurricane Ignacio (1985)
• Hurricane Gilma (1994)
• List of Hawaii hurricanes
• Pacific hurricane
• List of tropical cyclones