Cyclone Donna

{{Hatnote group|

{{About|the 2017 South Pacific tropical cyclone|the 1960 Atlantic hurricane|Hurricane Donna}}

}}

{{infobox weather event

| name = Severe Tropical Cyclone Donna

| image = Donna 2017-05-08 0230Z.jpg

| caption = Cyclone Donna north of New Caledonia at peak intensity on 8 May

| formed = 1 May 2017

| extratropical = 10 May 2017

| dissipated = 16 May 2017

}}{{infobox weather event/FMS

| winds = 110

| pressure = 935

}}{{infobox weather event/JTWC

| winds = 125

| pressure = 929

}}{{infobox weather event/Effects

| year = 2017

| fatalities = 2 total

| damage = 10000000

| areas = Solomon Islands, Vanuatu, New Caledonia, New Zealand

| refs =

}}{{infobox weather event/Footer

| season = 2016–17 South Pacific cyclone season

}}

Severe Tropical Cyclone Donna was the strongest off-season tropical cyclone in the Southern Hemisphere at the time, since surpassed by Cyclone Lola in 2023. The twenty-first tropical disturbance, third named storm, and second severe tropical cyclone of the annual cyclone season, Donna formed from an area of disturbed weather that was first monitored west-northwest of Fiji on 1 May 2017. The disturbance drifted eastward amid an increasingly favourable environment, and it was designated Tropical Depression 21F late on 2 May. Twelve hours later, it intensified into a Category 1 on the Australian tropical cyclone scale and was designated Tropical Cyclone Donna as the storm's motion shifted west and then south. After reaching its initial peak as a Category 4 cyclone early on 6 May, the effects of wind shear and upwelling caused the storm to weaken. However, it reintensified into a Category 5 cyclone on 8 May. Soon after, Donna entered a region of strong westerly flow and began to rapidly weaken. Continuing to accelerate in a southerly direction, Donna eventually weakened into a tropical low on 10 May. By 16 May, Donna's remnants had fully dissipated.

Buffeting the island chain of Vanuatu, Donna has resulted in severe damage throughout the northern provinces, though the exact extent is unknown in the absence of good communication.

Meteorological history

On 1 May, the day after the official end of the South Pacific cyclone season, the Joint Typhoon Warning Center (JTWC) began monitoring an area of disturbed weather about 1,455 km (905 mi) west-northwest of Nadi. Though it possessed an oblong area of low pressure partially exposed to the northeast of deep shower and thunderstorm activity, the system was embedded within an environment of moderate wind shear, good upper-level outflow, and warm ocean temperatures.{{cite report|title=Significant Tropical Weather Advisory for the western and South Pacific Oceans|url=http://gwydir.demon.co.uk/advisories/ABPW10-PGTW_201705010000.htm|archiveurl=https://archive.today/20240521235247/https://www.webcitation.org/6q9vRzHbV?url=http://gwydir.demon.co.uk/advisories/ABPW10-PGTW_201705010000.htm|publisher=Joint Typhoon Warning Center|date=1 May 2017|archivedate=21 May 2024|accessdate=7 May 2017|url-status=dead}} The official warning agency for the South Pacific, the Fiji Meteorological Service (FMS), began monitoring the disturbance a short while later.{{cite report|title=Tropical Disturbance Summary|url=http://gwydir.demon.co.uk/advisories/WWPS21-NFFN_201705010900.htm|archiveurl=https://archive.today/20240521235207/https://www.webcitation.org/6q9vipzeN?url=http://gwydir.demon.co.uk/advisories/WWPS21-NFFN_201705010900.htm|publisher=Fiji Meteorological Service|date=1 May 2017|archivedate=21 May 2024|accessdate=7 May 2017|url-status=dead}} As fragmented spiral bands began wrapping into the centre of circulation, the JTWC assessed that the potential for tropical cyclone formation was high, issuing a Tropical Cyclone Formation Alert accordingly at 21:00 UTC on 1 May.{{cite report|title=Tropical Cyclone Formation Alert|url=http://gwydir.demon.co.uk/advisories/WTPS21-PGTW_201705012100.htm|archiveurl=https://archive.today/20240521235128/https://www.webcitation.org/6q9vcddDn?url=http://gwydir.demon.co.uk/advisories/WTPS21-PGTW_201705012100.htm|publisher=Joint Typhoon Warning Center|date=1 May 2017|archivedate=21 May 2024|accessdate=7 May 2017|url-status=dead}} The storm tracked slowly eastward through the northern islands of Vanuatu but consolidated rapidly as upper-level winds became light, prompting the FMS to upgrade the disturbance to Tropical Depression 21F at 18:00 UTC on 2 May.{{cite report|title=Marine Weather Bulletin for Islands Area|url=http://gwydir.demon.co.uk/advisories/FQPS01-NFFN_201705021800.htm|archiveurl=https://archive.today/20240521235448/https://www.webcitation.org/6qBZ49xEF?url=http://gwydir.demon.co.uk/advisories/FQPS01-NFFN_201705021800.htm|publisher=Fiji Meteorological Service|date=2 May 2017|archivedate=21 May 2024|accessdate=7 May 2017|url-status=dead}} This was followed by the JTWC's classification of Tropical Cyclone 18P three hours later.

{{cite report|title=Tropical Cyclone 18P (Eighteen) Warning NR 001|url=http://gwydir.demon.co.uk/advisories/WTPS31-PGTW_201705022100.htm|archiveurl=https://archive.today/20240521235327/https://www.webcitation.org/6qBYjnD2f?url=http://gwydir.demon.co.uk/advisories/WTPS31-PGTW_201705022100.htm|publisher=Joint Typhoon Warning Center|date=2 May 2017|archivedate=21 May 2024|accessdate=7 May 2017|url-status=dead}}

Following formation, the depression turned west in response to a developing subtropical ridge to its south.{{cite report|title=Tropical Cyclone 18P (Donna) Warning NR 002|url=http://gwydir.demon.co.uk/advisories/WTPS31-PGTW_201705030900.htm|archiveurl=https://archive.today/20240521235408/https://www.webcitation.org/6qBYjRIq4?url=http://gwydir.demon.co.uk/advisories/WTPS31-PGTW_201705030900.htm|publisher=Joint Typhoon Warning Center|date=3 May 2017|archivedate=21 May 2024|accessdate=7 May 2017|url-status=dead}} A continued favourable environment allowed it to intensify into a Category 1 on the Australian tropical cyclone scale by 06:00 UTC on 3 May, at which point it was named "Donna" by the FMS,{{cite report|title=Hurricane Warning 003 Issued from RSMC Nadi May 030716 UTC|url=http://gwydir.demon.co.uk/advisories/WHPS01-NFFN_201705030600.htm|archiveurl=https://archive.today/20240521235528/https://www.webcitation.org/6qBZE8S6A?url=http://gwydir.demon.co.uk/advisories/WHPS01-NFFN_201705030600.htm|publisher=Fiji Meteorological Service|date=3 May 2017|archivedate=21 May 2024|accessdate=7 May 2017|url-status=dead}} and further to Category 2 intensity by 18:00 UTC.{{cite report|title=Hurricane Warning 005 Issued from RSMC Nadi May 031913 UTC|url=http://gwydir.demon.co.uk/advisories/WHPS01-NFFN_201705031800.htm|archiveurl=https://archive.today/20240521235651/https://www.webcitation.org/6qEbVPHB5?url=http://gwydir.demon.co.uk/advisories/WHPS01-NFFN_201705031800.htm|publisher=Fiji Meteorological Service|date=3 May 2017|archivedate=21 May 2024|accessdate=7 May 2017|url-status=dead}} The JTWC, meanwhile, upped the cyclone to the equivalent of a Category 1 hurricane on the Saffir–Simpson scale, citing consolidation of deep convection near the centre and satellite intensity estimates around 120 km/h (75 mph).{{cite report|title=Tropical Cyclone 18P (Donna) Warning NR 003|url=http://gwydir.demon.co.uk/advisories/WTPS31-PGTW_201705032100.htm|archiveurl=https://archive.today/20240521235810/https://www.webcitation.org/6qEeL0CI3?url=http://gwydir.demon.co.uk/advisories/WTPS31-PGTW_201705032100.htm|publisher=Joint Typhoon Warning Center|date=3 May 2017|archivedate=21 May 2024|accessdate=7 May 2017|url-status=dead}} Despite some evidence of wind shear along the northern fringes of the storm, it began to clear an eye late on 4 May, prompting the JTWC to classify Donna as a Category 2 equivalent,{{cite report|title=Tropical Cyclone 18P (Donna) Warning NR 005|url=http://gwydir.demon.co.uk/advisories/WTPS31-PGTW_201705042100.htm|archiveurl=https://archive.today/20240521235729/https://www.webcitation.org/6qEeJVL6e?url=http://gwydir.demon.co.uk/advisories/WTPS31-PGTW_201705050900.htm|publisher=Joint Typhoon Warning Center|date=4 May 2017|archivedate=21 May 2024|accessdate=7 May 2017|url-status=dead}} and the FMS to upgrade to Category 3 strength.{{cite report|title=Hurricane Warning 012 Issued from RSMC Nadi May 050114 UTC|url=http://gwydir.demon.co.uk/advisories/WHPS01-NFFN_201705050000.htm|archiveurl=https://archive.today/20240521235609/https://www.webcitation.org/6qEbTXrT2?url=http://gwydir.demon.co.uk/advisories/WHPS01-NFFN_201705050000.htm|publisher=Fiji Meteorological Service|date=5 May 2017|archivedate=21 May 2024|accessdate=7 May 2017|url-status=dead}} At 00:00 UTC on 6 May, after re-tracking through Vanuatu and beginning a southward track, Donna attained its initial peak as a Category 4 cyclone.{{cite report|title=Hurricane Warning 020 Issued from RSMC Nadi May 060115 UTC|url=http://gwydir.demon.co.uk/advisories/WHPS01-NFFN_201705060000.htm|archiveurl=https://archive.today/20240521235849/https://www.webcitation.org/6qG3w5ZH4?url=http://gwydir.demon.co.uk/advisories/WHPS01-NFFN_201705060000.htm|publisher=Fiji Meteorological Service|date=6 May 2017|archivedate=21 May 2024|accessdate=7 May 2017|url-status=dead}}{{cite web|url= http://www.stuff.co.nz/world/92300025/Cyclone-Donna-upgraded-to-category-four-storm |title= Cyclone Donna upgraded to category four storm |publisher= Stuff (Fairfax Media) |date=6 May 2017}}

Shortly thereafter, the effects of increased northeasterly upper-level flow became more prevalent as the storm's cloud pattern changed to a central cold cover and then devolved into patchy areas of moderate convection.{{cite report|title=Tropical Cyclone 18P (Donna) Warning NR 010|url=http://gwydir.demon.co.uk/advisories/WTPS31-PGTW_201705060300.htm|archiveurl=https://archive.today/20240521235930/https://www.webcitation.org/6qG4LwlMY?url=http://gwydir.demon.co.uk/advisories/WTPS31-PGTW_201705060300.htm|publisher=Joint Typhoon Warning Center|date=6 May 2017|archivedate=21 May 2024|accessdate=7 May 2017|url-status=dead}} Around 09:00 UTC on 6 May, the JTWC reduced the storm back to a Category 1 equivalent,{{cite report|title=Tropical Cyclone 18P (Donna) Warning NR 011|url=http://gwydir.demon.co.uk/advisories/WTPS31-PGTW_201705060900.htm|archiveurl=https://archive.today/20240522000011/https://www.webcitation.org/6qG4LWu8k?url=http://gwydir.demon.co.uk/advisories/WTPS31-PGTW_201705060900.htm|publisher=Joint Typhoon Warning Center|date=6 May 2017|archivedate=22 May 2024|accessdate=7 May 2017|url-status=dead}} and by 18:00 UTC, the FMS indicated Donna had weakened to a Category 3 cyclone on the Australian scale.{{cite report|title=Hurricane Warning 026 Issued from RSMC Nadi May 061909 UTC|url=http://gwydir.demon.co.uk/advisories/WHPS01-NFFN_201705061800.htm|archive-url=https://archive.today/20240522000252/https://www.webcitation.org/6qJWp2GDk?url=http://gwydir.demon.co.uk/advisories/WHPS01-NFFN_201705061800.htm|url-status=dead|archive-date=22 May 2024|publisher=Fiji Meteorological Service|date=6 May 2017|accessdate=7 May 2017}}

Drifting south-southwest and then south, Donna continued to struggle under the combined effects of upper-level winds and ocean upwelling.{{cite report|title=Tropical Cyclone 18P (Donna) Warning NR 014|url=http://gwydir.demon.co.uk/advisories/WTPS31-PGTW_201705070300.htm|archive-url=https://archive.today/20240522000613/https://www.webcitation.org/6qJXX2hBg?url=http://gwydir.demon.co.uk/advisories/WTPS31-PGTW_201705070300.htm|url-status=dead|archive-date=22 May 2024|publisher=Joint Typhoon Warning Center|date=6 May 2017|accessdate=7 May 2017}} By early on 7 May, however, convection within the eyewall began to increase in intensity,{{cite report|title=Tropical Cyclone 18P (Donna) Warning NR 016|url=http://gwydir.demon.co.uk/advisories/WTPS31-PGTW_201705071500.htm|archive-url=https://archive.today/20240522000538/https://www.webcitation.org/6qJXWFunU?url=http://gwydir.demon.co.uk/advisories/WTPS31-PGTW_201705071500.htm|url-status=dead|archive-date=22 May 2024|publisher=Joint Typhoon Warning Center|date=7 May 2017|accessdate=7 May 2017}} and the FMS upgraded Donna to a Category 4 cyclone for a second time accordingly.{{cite report|title=Hurricane Warning 035 Issued From RSMC Nadi May 071903 UTC|url=http://gwydir.demon.co.uk/advisories/WHPS01-NFFN_201705071800.htm|archive-url=https://archive.today/20240522000214/https://www.webcitation.org/6qJWnLqzN?url=http://gwydir.demon.co.uk/advisories/WHPS01-NFFN_201705071800.htm|url-status=dead|archive-date=22 May 2024|publisher=Fiji Meteorological Service|date=7 May 2017|accessdate=7 May 2017}} Three hours later, the JTWC estimated that it had intensified to a Category 4 equivalent, completely skipping Category 3 status.{{cite report|title=Tropical Cyclone 18P (Donna) Warning NR 017|url=http://gwydir.demon.co.uk/advisories/WTPS31-PGTW_201705072100.htm|archive-url=https://archive.today/20240522000452/https://www.webcitation.org/6qJXVuiSi?url=http://gwydir.demon.co.uk/advisories/WTPS31-PGTW_201705072100.htm|url-status=dead|archive-date=22 May 2024|publisher=Joint Typhoon Warning Center|date=7 May 2017|accessdate=7 May 2017}} With a solid ring of deep convection surrounding a well-defined 55 km (35 mi) eye,{{cite report|title=Tropical Cyclone 18P (Donna) Warning NR 018|url=http://gwydir.demon.co.uk/advisories/WTPS31-PGTW_201705080300.htm|archive-url=https://archive.today/20240522000412/https://www.webcitation.org/6qJXVTjfC?url=http://gwydir.demon.co.uk/advisories/WTPS31-PGTW_201705080300.htm|url-status=dead|archive-date=22 May 2024|publisher=Joint Typhoon Warning Center|date=8 May 2017|accessdate=8 May 2017}} the FMS upgraded Donna to a Category 5 cyclone at 00:00 UTC on 8 May, estimating that the storm possessed 10-minute sustained winds of 205 km/h (125 mph).{{cite report|title=Hurricane Warning 038 Issued From RSMC Nadi May 080118 UTC|url=http://gwydir.demon.co.uk/advisories/WHPS01-NFFN_201705080000.htm|archive-url=https://archive.today/20240522000131/https://www.webcitation.org/6qJWmysqr?url=http://gwydir.demon.co.uk/advisories/WHPS01-NFFN_201705080000.htm|url-status=dead|archive-date=22 May 2024|publisher=Fiji Meteorological Service|date=8 May 2017|accessdate=8 May 2017}} As a result, Donna became the strongest off-season tropical cyclone on record during the month of May in the South Pacific basin.{{cite news|author=Matt Burrows|title=Cyclone Donna now category 5, breaks global record|url=http://www.newshub.co.nz/home/world/2017/05/cyclone-donna-now-category-5-breaks-global-record.html|archive-url=https://web.archive.org/web/20170511144216/http://www.newshub.co.nz/home/world/2017/05/cyclone-donna-now-category-5-breaks-global-record.html|url-status=dead|archive-date=11 May 2017|newspaper=Newshub |date=8 May 2017|accessdate=8 May 2017}} Weakening began shortly following peak intensity as Donna's eye became partially obscured and the eastern eyewall was eroded;{{cite web|title=Tropical Cyclone 18P (Donna) Warning NR 019|url=http://gwydir.demon.co.uk/advisories/WTPS31-PGTW_201705080900.htm|archiveurl=https://archive.today/20240522000333/https://www.webcitation.org/6qJXV88lw?url=http://gwydir.demon.co.uk/advisories/WTPS31-PGTW_201705080900.htm|publisher=Joint Typhoon Warning Center|date=8 May 2017|archivedate=22 May 2024|accessdate=11 May 2017|url-status=dead}} the storm weakened back to Category 4 intensity by 18:00 UTC on 8 May,{{cite web|title=Hurricane Warning 047 Issued from RSMC Nadi May 081919 UTC|url=http://gwydir.demon.co.uk/advisories/WHPS01-NFFN_201705081800.htm|archiveurl=https://archive.today/20240522000051/https://www.webcitation.org/6qJWlzIUK?url=http://gwydir.demon.co.uk/advisories/WHPS01-NFFN_201705081800.htm|publisher=Fiji Meteorological Service|date=9 May 2017|archivedate=22 May 2024|accessdate=11 May 2017|url-status=dead}} Category 1 intensity by 21:00 UTC on 9 May,{{cite web|title=Gale Warning 063 Issued from RSMC Nadi May 092152 UTC|url=http://gwydir.demon.co.uk/advisories/WTPS01-NFFN_201705092100.htm|archiveurl=https://archive.today/20240522000734/https://www.webcitation.org/6qMVYpKoF?url=http://gwydir.demon.co.uk/advisories/WTPS01-NFFN_201705092100.htm|publisher=Fiji Meteorological Service|date=9 May 2017|archivedate=22 May 2024|accessdate=11 May 2017|url-status=dead}} and ultimately degenerated into a tropical low by 06:00 UTC on 10 May as it dodged New Caledonia.{{cite web|title=Gale Warning 067 Issued from RSMC Nadi May 100840 UTC|url=http://gwydir.demon.co.uk/advisories/WOPS01-NFFN_201705100800.htm|archiveurl=https://archive.today/20240522000653/https://www.webcitation.org/6qMVVaDl4?url=http://gwydir.demon.co.uk/advisories/WOPS01-NFFN_201705100800.htm|publisher=Fiji Meteorological Service|date=10 May 2017|archivedate=22 May 2024|accessdate=11 May 2017|url-status=dead}}

Preparations and impact

According to Aon Benfield Inc. in January 2018, Donna was responsible for two deaths and a total of US$10 million in damage.{{cite web|title=Companion Volume to Weather, Climate & Catastrophe Insight|url=http://thoughtleadership.aonbenfield.com/Documents/20180124-ab-if-annual-companion-volume.pdf|publisher=Aon Benfield|date=24 January 2018|accessdate=30 January 2018|archive-date=2 March 2018|archive-url=https://web.archive.org/web/20180302001946/http://thoughtleadership.aonbenfield.com/Documents/20180124-ab-if-annual-companion-volume.pdf|url-status=dead}}

=Vanuatu=

As Donna buffeted Vanuatu, entire villages across the Torres Islands of Torba Province were forced to seek refuge in caves. Throughout the province, buildings were destroyed and others had their roofs ripped off. Heavy rainfall led to flooding of low-lying areas of Efate. In Port Vila, rushing water carved out large chunks of land that resulted in structural collapse.{{cite web|title=Tropical Cyclone Donna becomes Category 5 storm, worst May storm on record in South Pacific|url=http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=11851466|work=The New Zealand Herald|date=8 May 2017|accessdate=8 May 2017}} Across the entire northern half of the island chain, crops sustained significant damage and water sources were contaminated, though the full extent of the damage was unknown as a result of severed communications.{{cite web|title=Still fierce, Cyclone Donna moving towards New Caledonia|url=http://www.radionz.co.nz/international/pacific-news/330274/still-fierce,-cyclone-donna-moving-towards-new-caledonia|publisher=Radio New Zealand|date=8 May 2017|accessdate=8 May 2017}}{{cite web|url= http://www.stuff.co.nz/world/south-pacific/92306587/cyclone-donna-lashes-vanuatu-with-winds-gusting-up-to-240kmh |title= Cyclone Donna lashes Vanuatu |publisher= Stuff (Fairfax Media) |date=7 May 2017}}

=Solomon Islands=

In the Temotu Province, Donna caused two fatalities; an adult who was struck by a fallen branch and a primary school student of Tarano School who drowned on an out-board motorboat when crossing from one-side to the other side of a lake.{{cite news|title=Damages reported in Temotu|url=http://www.solomonstarnews.com/news/national/12838-damages-reported-in-temotu|work=Solomon Star|date=15 May 2017|archiveurl=https://web.archive.org/web/20170521093921/http://www.solomonstarnews.com/news/national/12838-damages-reported-in-temotu|archivedate=21 May 2017|url-status=dead}}

=New Zealand=

Moisture from the remnants of Donna combined with a weakening Tasman Sea low to produce heavy rains over much of the North Island and the west coast of the South Island. In expectation of more than {{convert|100|mm|in|abbr=on}} of rain, heavy rain warnings were issued for Nelson and the Bay of Plenty regions, while severe weather warnings were issued for much of the North Island.{{cite news|title=Heavy rain forecast for Thursday and Friday as Donna combines with Tasman low|url=http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=11853271|accessdate=11 May 2017|work=The New Zealand Herald|date=10 May 2017}}{{cite news|last1=Newshub staff|title=Weather: Cyclone Donna leftovers bring heavy rain to New Zealand|url=http://www.newshub.co.nz/home/new-zealand/2017/05/weather-cyclone-donna-leftovers-bring-heavy-rain-to-new-zealand.html|archive-url=https://web.archive.org/web/20170510225417/http://www.newshub.co.nz/home/new-zealand/2017/05/weather-cyclone-donna-leftovers-bring-heavy-rain-to-new-zealand.html|url-status=dead|archive-date=10 May 2017|accessdate=11 May 2017|publisher=Newshub |date=11 May 2017}}