Updated Saturday 14 March 2015 11 pm

BILL SINGH, METSERVICE METEOROLOGIST Severe Tropical Cyclone Pam was located about 400km east of Noumea, New Caledonia at 7 pm Saturday evening. The cyclone is moving south-southeast at about 25km/hr, away from Vanuatu and New Caledonia. The visible satellite imagery at 7pm shows tropical cyclone (TC) Pam still has an eye, indicating hurricane force winds close to the centre. TC Pam is a Category 5 cyclone with 230 km/hr winds close to the centre. On its current track, the system is expected to move south of 25S, into MetService area of responsibility by 7 am this morning (Sunday, 15th March) and continue to weaken.

Visible imagery at 7 pm Visible imagery at 7 pm

 

TC Pam track map issued by RSMC Nadi issued at 9pm TC Pam track map issued by RSMC Nadi issued at 9pm

 

TC Pam is expected to have a large impact on New Zealand weather as it heads towards the southeast. The centre of TC Pam is expected to be located about 550 km northeast of Auckland early Sunday evening and about 150 km east of East Cape around midday Monday, 16th March. Image below shows a good agreement with the positons of TC Pam from 3 weather models (UK, ECMWF and GFS) during Sunday and Monday.

Position of TC Pam from three global models Position of TC Pam from three global models

 

What happens when a cyclone moves south of 25S?

MetService will take responsibility from Fiji once TC Pam crosses south of 25S (from 7 am Sunday morning) and will issue all tropical cyclone warnings for the cyclone. A tropical cyclone gets its energy from warm tropical oceans, and once it moves over cooler waters, the structure of the cyclone gradually changes. The eye which is clearly visible now would get filled by upper clouds as the height of the tropopause lowers. The intensity of the cyclone will gradually weaken as wind shear over the system increases, however the maximum winds around the centre are still expected to be of hurricane intensity north of 35S. The area of gales is expected to become larger than its current size to conserve momentum. At this stage, TC Pam is expected to remain warm cored (a signature of all tropical cyclones) till around 35S, then cooler air is expected to intrude the system as it moves towards 40S.

Impact of TC Pam on New Zealand

TC Pam is expected to have a large impact on New Zealand weather, bringing heavy rain and gale force winds to parts of the North Island. The latest warnings and watches for New Zealand can be found here . A warning for heavy rain has been issued for Gisborne, Hawkes Bay and the ranges of Eastern Bay of Plenty. A warning for severe gales has been issued for Great Barrier Island, Coromandel Peninsula, Eastern Northland, Gisborne and eastern areas of Bay of Plenty. Watches for severe gales have been issued for a broader area including the remaining parts of Northland, northern part of Auckland and northern Hawkes Bay. A watch for heavy rain has been issued for Eastern Northland and Coromandel including Great Barrier Island. The watch is also an alert for dangerous coastal conditions over the east coast of the North Island from Cape Reinga to Wairarapa. Cyclone Pam is expected to bring heavy swells and very large waves to eastern coastal areas of North Island. The image below shows at least 7 metre waves affecting eastern coastal areas, starting near Cape Reinga during Sunday evening then spreading to Gisborne coastal areas during Monday morning.

Combined Waves during Sunday evening and Monday morning Combined Waves during Sunday evening and Monday morning

 

The next update will be issued by 6 am Sunday 15 March.

Update Saturday 14 March 2015 5pm

DAVID MILLER, METSERVICE METEOROLOGIST As at 4pm today, severe tropical cyclone Pam was located about 200 nautical miles south of Port Vila and about 200 nautical miles east of Noumea in New Caledonia. The Tropical cyclone is then expected to move southeast over the next couple of days. Refer to the latest TC track map issued by RSMC Nadi at 2:18pm today.

Latest infrared satellite image at 4pm local time, showing the position of severe TC Pam. Latest infrared satellite image at 4pm local time, showing the position of severe TC Pam.

 

   

Latest TC forecast track map issued by RSMC Nadi at 2:18pm. Latest TC forecast track map issued by RSMC Nadi at 2:18pm.

 

  Once the eye of Pam moves south past 25S, Metservice takes over responsibility of issuing Tropical Cyclone Bulletins and associated warnings from RSMC Nadi. The diagram below shows the areas of responsibility for tropical cyclones. At this stage, Pam is expected to cross 25S around 7am tomorrow morning (Sunday).  

Tropical cyclone warning centres area of responsibility. Tropical cyclone warning centres area of responsibility.

 

As well as issuing warnings over land, Metservice routinely issues high seas forecasts within our area of responsibility. These bulletins describe areas of strong winds, heavy swells, and areas of poor visibility, and refer to warnings in the area. You can find a link to the subtropics bulletin here http://www.metservice.com/marine-surf/high-seas/subtropic. Aviation forecasters will also be busy issuing warnings for the aviation industry known as Sigmets (short for Significant Meteorological conditions). These warnings are written in standardised code for ease of use around the world. The latest warnings and watches for New Zealand can be found here www.metservice.com/warnings/home . Cyclone Pam is expected to have a large impact in New Zealand. A warning for heavy rain has been issued for Gisborne, the northern Hawkes Bay ranges and the ranges of Eastern Bay of Plenty. A warning for severe gales has been issued for the Bay of Plenty, especially in the east and for Gisborne. Watches for severe gales have been issued for a broader area including Northland, Coromandel, Great Barrier Island and northern Hawkes Bay. A watch for heavy rain has been issued for Eastern Northland and Coromandel including Great Barrier Island, and Hawkes Bay (except northern Hawkes Bay where a Warning is in force). The watch is also an alert for dangerous coastal conditions over the east coast of the North Island from Cape Reinga to Wairarapa. Note that sea conditions are expected to become extremely dangerous on the north and east coasts of the North Island. This is a map showing swell height in metres at midday on Monday. This swell is exceptionally large, especially in Gisborne and the Bay of Plenty where it could be about 7 metres. This is likely to lead to widespread coastal erosion. Anyone considering venturing near or into the water should take extra precautions and be sure to check the latest forecasts for expected dangerous conditions.

Swell forecast from the ECMWF for noon on Monday, height in metres. Swell forecast from the ECMWF for noon on Monday, height in metres.

 

The next update will be issued by 11pm.  

Update Saturday 14th March at 10:00am

HORDUR THORDARSON, METSERVICE METEOROLOGIST Tropical cyclone Pam has been severely affecting Vanuatu this morning with the centre passing just east of the capital city, Port Vila on the island Efate. From there it has moved south-southeast to the islands Erromango and Tanna. It is expected to lie just south of Tanna at noon today. This is one of the most intense storms on record with a central pressure estimated at near 890 hectoPascals and sustained winds of around 250 kilometres per hour near the centre. Winds of this strength have the potential to cause catastrophic damage with dangerous flying debris and structural destruction. caption

Infra red image from 7:32am this morning:

  For imagery showing an animation of the eye of the cyclone please use this link: http://tropic.ssec.wisc.edu/real-time/mimic-tc/2015_17P/webManager/basicGifDisplay48.html   Caption A snapshot from the animation, showing the tropical cyclone early this morning as the centre passed just east of Efate in Vanuatu, on course towards the islands to the south-southeast South of Vanuatu,Severe Tropical Cyclone Pam should be affected by a north-westerly flow at upper levels. This flow should steer Pam onto a south-easterly track that should bring it into the area northeast of New Zealand on Sunday. There is still some uncertainty with respect to the track, so people are advised to keep up with the latest forecasts, watches and warnings on our webpage, www.metservice.com. Cyclone Pam is expected to have a large impact in New Zealand. A warning for heavy rain has been issued for Gisborne, the northern Hawkes Bay ranges and the ranges of Eastern Bay of Plenty. A warning for severe gales has been issued for the Bay of Plenty, especially in the east and for Gisborne. Watches for severe gales have been issued for a broader area including Northland, Coromandel, Great Barrier Island and northern Hawkes Bay. A watch for heavy rain has been issued for Eastern Northland and Coromandel including Great Barrier Island. The watch is also an alert for dangerous coastal conditions over the east coast of the North Island from Cape Reinga to Wairarapa. Note that sea conditions are expected to become extremely dangerous on the north and east coasts of the North Island. This is a map showing swell height in metres at midday on Monday. This swell is exceptionally large, especially in Gisborne and the Bay of Plenty where it could be about 7 metres. This is likely to lead to widespread coastal erosion. Anyone considering venturing near or into the water should take extra precautions and be sure to check the latest forecasts for expected dangerous conditions.

caption Swell forecast from the ECMWF for noon on Monday, height in metres.

 

 

Update Saturday 14th March at 5.00am

MATTHEW FORD, METSERVICE METEOROLOGIST

Infrared satellite image of TC Pam 3.44am Sat 14th March 2015 Infrared satellite image of TC Pam 3.44am Sat 14th March 2015

 

At 1am this morning (NZ local time) severe tropical cyclone Pam was located about 70km east of Port Vila, Vanuatu. TC Pam is still a category 5 cyclone, and has intensified slightly overnight with the central pressure dropping to an estimated 899hPa and winds close to the centre of about 250km/h. The area of gales (65km/h winds) is estimated to extend up to 380km from the centre of the cyclone, affecting much of Vanuatu. TC Pam is still moving slowly south, and is expected to cross the southern Vanuatu islands of Erromango and Tanna during the next 12 hours while intensifying slightly. The above image is an infrared satellite picture of TC Pam taken at 3.44am this morning. Infrared images are colour coded to show the temperature of the cloud tops, which may extend high up into the atmosphere. The eye of the tropical cyclone is the light coloured dot in the middle surrounded by the dark blue (cloud tops of about -82C). What this image shows is the intensely cold cloud tops of thunderstorms surrounding the relatively warm eye of the tropical cyclone. This temperature contrast is one of the ways forecasters can estimate the intensity of a tropical cyclone from satellite imagery. The latest forecast track map for TC PAM was issued by RSMC Nadi, Fiji at 2.24am this morning. The map shows that TC PAM is expected to take a southeast track to the northeast of New Zealand over the next couple of days. Although the map shows that the category of the system will change as it approaches New Zealand, decreasing from 5 at the moment to 1 south of 30S, this just reflects the fact that the system is moving out of the tropics and is losing its tropical character. The cyclone will remain a very intense storm, with heavy rain, severe gales and high seas associated with it. Please refer to the latest severe weather watches and warnings issued by MetService for more information on its possible impact on New Zealand's weather.

TC Pam track map issued by RSMC Nadi 2.24am 14th March 2015 TC Pam track map issued by RSMC Nadi 2.24am 14th March 2015

 

  Sources: Fiji Meteorological Service / RSMC Nadi Tropical Cyclone Warning Centre MTSAT satellite imagery courtesy of Japan Meteorological agency