Cyclone Pam: Vanuatu Direct Hit (RECAP)

Cyclone Pam made a direct hit -- packing Category 5 winds -- on March 13 in the Republic of Vanuatu in the South Pacific Ocean, including the capital city of Port Vila. This will likely be one of the worst natural disasters in the island chain's history.

(MORE: Cyclone Pam Latest News)

As of early Monday morning local time (15 hours ahead of U.S. Eastern Daylight Time), Pam continued to weaken as it moved to the southeast well away from Vanuatu, and the Joint Warning Typhoon Center issued its final advisory for the cyclone.

At the height of its strength, during the evening to late night hours on March 13 (local time), Cyclone Pam produced winds as high as 165 mph, making it the equivalent of a Category 5 hurricane during its closes approach to the islands. The western edge of the eye of Cyclone Pam scraped the eastern edge of Efate island, including the capital of Vanuatu, Port Vila (population 44,000), at about 11 p.m. Friday night, local time.

One satellite estimate from the University of Wisconsin suggested Pam's central pressure may have been as low as 890 millibars. Another estimate Friday morning, U.S. time had a lower pressure (879 millibars). In general, the lower the central pressure, the stronger the tropical cyclone. 

The University of Wisconsin estimate is lower (stronger) than all but two Atlantic hurricanes all-time (Wilma '05: 882 millibars and Gilbert '88: 888 millibars). The all-time lowest pressure measured on the Earth's surface was in Super Typhoon Tip (870 millibars) in October 1979. Without reconnaissance aircraft to provide a direct measurement, we'll never know the actual lowest central pressure of Cyclone Pam.

According to data from Australia's Bureau of Meteorology, Port Vila may have been spared the absolute worst-case scenario. BOM wind data showed a peak gust of 60 mph at 12:51 a.m. Saturday local time (9:51 a.m. EDT Friday in the U.S.). This came about an hour after the pressure bottomed out at 942.1 millibars there.

Water levels peaked about 2 feet above normal tide levels, according to the BOM gauge at Port Vila.

(INTERACTIVE MAP: Vanuatu)

The Vanuatu National Disaster Management Office had issued a red alert for the entire island chain. 

• Some complete building failures. Small utility buildings blown over or away.
• Severe and extensive window, door damage.
• Complete destruction of mobile homes.
• All shrubs, trees, signs blown down.

(MORE: The World's Most Vulnerable Cities For Natural Disasters)

The Republic of Vanuatu is an island chain about 1,200 miles northeast of Brisbane, Australia, with a total population of around 224,000.

Pam's large circulation had already lead to wave-induced coastal flooding on Vaitupu Island, Tuvalu on March 12, according to storm surge specialist, Dr. Hal Needham (thanks to Weather Underground's Dr. Jeff Masters for passing this along) and The Weather Channel hurricane specialist, Michael Lowry. This was just under 800 miles northeast of the center of Pam at the time.

(MORE: Hurricane Central)

Are Category Fives Unusual There?

In reliable records dating to 1970, there have been nine other Category 5 cyclones in the southwest Pacific Ocean basin, according to hurricane specialist, Michael Lowry. Cyclone Ului was the last to do so in March 2010 well west of Vanuatu in the Coral Sea.

Based on that, one would expect "about one Cat. 5 (cyclone) every five years" in the southwest Pacific basin, says Lowry.

Of course, with no reconnaissance aircraft missions in this part of the world, cyclone intensities are assigned using satellite estimates.

The Atlantic basin has not had a single Category 5 hurricane since Hurricane Felix in early September 2007.

November through April is the season for tropical cyclones in the southwest Pacific Ocean, called simply "cyclones" there, rather than "hurricanes" or "typhoons". Cyclones Lam and Marcia made landfall in northern Australia in mid-late February. 

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