:Cyclone Vaianu

{{storm path|Vaianu 2006 track.png}}

Late on February 9, the Regional Specialized Meteorological Centre (RSMC) in Nadi, Fiji reported that Tropical Depression 12F had developed within a convergence zone which was located about {{convert|140|km|mi|abbr=on}} to the northeast of Vanua Levu.{{cite web|url=http://mtarchive.geol.iastate.edu/2006/02/09/text/Severe/Severe_09.txt|title=Severe Weather Warnings issued on 2006-02-09|date=February 9, 2006|publisher=MT Archive|access-date=January 30, 2010}} The depression tracked southeastward, although further development was initially inhibited by wind shear. During the next day, the depression turned towards the southeast and moved into a more favorable environment for intensification. It was then designated as Tropical Depression 11P at 1800 UTC by the Joint Typhoon Warning Center (JTWC).{{cite web|publisher=Joint Typhoon Warning Center|access-date=January 27, 2010|title=JTWC Best Track for Cyclone Vaianu|url=http://www.usno.navy.mil/NOOC/nmfc-ph/RSS/jtwc/best_tracks/2006/2006s-bsh/bsh112006.txt|archive-date=June 6, 2011|archive-url=https://web.archive.org/web/20110606203744/http://www.usno.navy.mil/NOOC/nmfc-ph/RSS/jtwc/best_tracks/2006/2006s-bsh/bsh112006.txt|url-status=dead}} On February 11, the system significantly organized,{{cite web|author=Simon Clarke|publisher=Typhoon 2000|date=April 25, 2006|access-date=January 27, 2010|title=Monthly Tropical Weather Summary for February 2006|url=http://www.typhoon2000.ph/garyp_mgtcs/feb06sum.htm}} and at 1200 UTC that day, RSMC Nadi reported that the depression had intensified into a Category 1 tropical cyclone on the Australian tropical cyclone intensity scale; it was assigned the name Vaianu.{{cite web |publisher=Fiji Meteorological Service |date=September 8, 2007 |access-date=January 27, 2010 |title=Tropical Cyclone Summary: 2005-2006 Season |url=http://www.met.gov.fj/documents/TC_Seasonal_Summary_05-061190690520.pdf |url-status=dead |archive-url=https://web.archive.org/web/20081001150802/http://www.met.gov.fj/documents/TC_Seasonal_Summary_05-061190690520.pdf |archive-date=October 1, 2008 }}

At the time of being upgraded to a cyclone, Vaianu was situated about {{convert|190|km|mi|abbr=on}} to the northwest of Vavaʻu, a Tonga island chain. The storm turned southwestward under the steering currents of a ridge to the southeast. The JTWC recognized the system as a tropical storm on February 12, and upgraded it into a tropical cyclone shortly thereafter. Vaianu continued to strengthen, and passed west of Tonga. The JTWC reported that the cyclone peaked in intensity at 1200 UTC on February 13, with maximum sustained 1-minute winds of 140 km/h (85 mph). RSMC Nadi assessed the storm as having peaked slightly later, with 10-minute winds of 130 km/h (80 mph), which made it a Category 3 severe tropical cyclone.

The storm held its strength for some time as it moved southward between Ono-i-Lau and Tongatapu. Beginning to accelerate, Vaianu entered the area of responsibility of the Tropical Cyclone Warning Centre in Wellington, New Zealand. It curved southeastward and slowly deteriorated due to increasing wind shear and colder sea surface temperatures. The JTWC downgraded it to a tropical storm on February 15, and by the next day it was undergoing extratropical transition. At 0600 UTC, the JTWC classified it as extratropical, but it remained a powerful storm system for several days as it tracked over the open ocean.

File:Vaianu 15 feb 2006 0135Z.jpg

Early on February 10, RSMC Nadi placed Niuafo'ou and Niuatoputapu under a tropical cyclone alert, before early the next day extending the alert to the whole of Tonga.{{cite web|url=http://mtarchive.geol.iastate.edu/2006/02/10/text/Severe/Severe_10.txt|title=Severe Weather Warnings issued on 2006-02-10|date=February 10, 2006|publisher=MT Archive|access-date=January 27, 2010}}{{cite web|url=http://mtarchive.geol.iastate.edu/2006/02/11/text/Severe/Severe_11.txt|title=Severe Weather Warnings issued on 2006-02-11|date=February 11, 2006|publisher=MT Archive|access-date=January 27, 2010}} Later that day the Vavau, Haapai, and Nomuka islands were placed under a gale warning. The warnings stayed in force until late on February 12 when the gale warning was canceled, and concurrently, southern Tonga was placed under a tropical cyclone warning.{{cite web|url=http://mtarchive.geol.iastate.edu/2006/02/12/text/Severe/Severe_12.txt|title=Severe Weather Warnings issued on 2006-02-12|date=February 12, 2006|publisher=MT Archive|access-date=January 27, 2010}} These warnings were canceled on February 14.{{cite web|url=http://mtarchive.geol.iastate.edu/2006/02/13/text/Severe/Severe_13.txt|title=Severe Weather Warnings issued on 2006-02-13|date=February 13, 2006|publisher=MT Archive|access-date=January 27, 2010}}{{cite web|url=http://mtarchive.geol.iastate.edu/2006/02/14/text/Severe/Severe_14.txt|title=Severe Weather Warnings issued on 2006-02-14|date=February 14, 2006|publisher=MT Archive|access-date=January 27, 2010}} During the cyclone, RSMC Nadi placed the Lau Islands under a strong wind warning, and a damaging swell warning was declared for Fiji. Businesses in Nuku'alofa closed as the storm passed by.

At the Fuaʻamotu station, sustained winds blew at {{convert|68|km/h|mph|abbr=on}} during the worst of the storm, with gusts reaching {{convert|100|km/h|mph|abbr=on}}. Barometric pressure there fell to 995 millibars at 1400 UTC on February 13, and {{convert|97.7|mm|in|abbr=on}} of rain fell.{{cite web|author=|title=A report on Tropical Cyclone "Vaianu"|date=March 30, 2006|publisher=Tonga Meteorological Service|access-date=January 27, 2010|url=http://www.met.gov.to/index_files/tc_vaianu_report_2006.pdf}} Since the cyclone remained predominantly over water, its effects were limited. Nonetheless, portions of Tongan experienced torrential rainfall and high winds. On Tongatapu and Eua, the storm inflicted extensive crop damage, and it is estimated that 70% of the banana crop was destroyed. While little property damage took place, the storm caused power outages across its path that took up a week to fully restore. In Nuku'alofa, the capital of Tonga, flooding of low-lying areas reportedly shut down the city for two days. The high winds brought down trees and dispersed debris throughout the region, while schools were forced to close.{{cite news|author=Staff Writer|title=Big clean-up for Tongan citizens after storm|date=February 15, 2006|newspaper=The New Zealand Herald|access-date=January 27, 2010|url=http://www.nzherald.co.nz/world/news/article.cfm?c_id=2&objectid=10368363}}

{{Portal|Tropical cyclones}}

• 2005–06 South Pacific cyclone season

{{Reflist|2}}

{{SPAC EL's}}

{{2005–06 South Pacific cyclone season buttons}}

{{Category 3 South Pacific severe tropical cyclones}}

{{Good article}}

{{DEFAULTSORT:Vaianu (2006)}}

Category:2005–06 South Pacific cyclone season

Category:Tropical cyclones in Tonga

Category:Category 3 South Pacific cyclones

Vaianu