Sunday 15 March 2015 10pm

RAMON OOSTERKAMP, MANAGER FORECASTING OPERATIONS

At 9pm Tropical Cyclone “Pam”, a Category 3 Cyclone, is lying near 32.8S 178.5E, or about 500km east-northeast of Cape Reinga moving swiftly southeast at 55 km/h. We are expecting “Pam” to recurve a little southward before passing about 150km east of East Cape at midday tomorrow.

Winds are increasing along eastern shores of Northland, through the Hauraki Gulf, Coromandel and Bay of Plenty. Southeast winds are currently gusting 110 to 120km/h in exposed places, with waves of 4.5 metres near Tutukaka. There are reports of homes without power in Kamo, Whangarei.

Reclassification of Tropical Cyclone Pam is expected to occur near 35S, which at this stage is likely to be early Monday morning.

Tropical cyclones begin their life cycle by feeding on the warm waters to our north, they require at least 26°C to form. Once they move out of the tropics they begin to change their structure, and as the sea surface temperature decreases, it becomes harder to maintain deep convection near the centre. In tropical cyclones, the strongest winds are near the centre, and, as the cyclone evolves, the strongest winds move away from the centre. Another clue that this evolution is happening is the loss of a symmetrical look.

The image on the left is TC Pam at 9pm on Saturday (Cat 5 – 890hPa) and the one on the right is Pam at 6pm Sunday (Cat 3 – 955hPa) The image above is TC Pam at 9pm on Saturday (Cat 5 – 890hPa) and the one below is Pam at 6pm Sunday (Cat 3 – 955hPa)

pam at 05Z 15 Mar

You can clearly see the loss of structure, symmetry, and the eye! The strongest winds have decreased from 130 knots to 80 knots, but gales have spread out to affect a much larger area. The eye has filled, and the cyclone is beginning to look somewhat ragged; all evidence that Pam will soon evolve from a tropical cyclone to a mid latitude cyclone .

Reclassification does not mean that "Pam" no longer poses any threat. Extremely strong wind gusts, heavy rain and phenomenal waves are still expected, and details can be found in http://www.metservice.com/warnings/home as well as in http://blog.metservice.com/ or http://www.metservice.com/national/home

The next update to this blog will around midnight Sunday 15 March .

Sunday 15 March 2015 8pm

ARNO DYASON, METSERVICE METEOROLOGIST

TC Pam to the north of New Zealand at 11am this morning. TC Pam to the north of New Zealand at 11am this morning.

Currently cyclone Pam is situated 450km to the north of the New Zealand coastline and still tracking southeast at 55m/h. It is expected to lie about 150km east of East Cape (northern Gisborne) by midday Monday, then move away from the New Zealand coastline towards Chatham Island.

 

Track of TC Pam. The orange lines mark the uncertainty of the track. Times are given in UTC, add 13 hours for New Zealand local time. Track of TC Pam. The orange lines mark the uncertainty of the track. Times are given in UTC, add 13 hours for New Zealand local time.

 

ECMWF model showing the low centre to the east of the north island at midday Monday 16 March. ECMWF model showing the low centre to the east of the north island at midday Monday 16 March.

Strong southeast winds and rain are expected over much of the North Island tonight and Monday, along with extremely large seas about the east coast. Wind gusts of 160 km/h or more are possible about the eastern Bay of Plenty and northern parts of Gisborne. Winds of this strength are likely to cause damage to trees and powerlines and could lift roofs and make for hazardous driving conditions. A burst of heavy rain accompanies these winds, with 180-220 mm possible about the Gisborne ranges. Please refer to the latest severe weather warnings and watches issued by MetService for more information.

Significant combined waves in metres for midnight Sunday 15 March (left), midday Monday 16 March (middle) and midnight Monday 16 March (right). Significant combined waves in metres for midnight Sunday 15 March (left), midday Monday 16 March (middle) and midnight Monday 16 March (right).

The image above shows the total combined waves (sea and swell) generated by cyclone Pam, which are expected to rise to 7-8m around the northern New Zealand coastline and even up to 9m around the northern Gisborne coast.

For any further information go to: http://www.metservice.com/national/home
The next update to this blog will be around midnight Sunday 15 March.

Sunday 15 March 2015 16:00 pm

ARNO DYASON, METSERVICE METEOROLOGIST

At 1pm this afternoon (NZ local time) Tropical Cyclone Pam was located about 500km to the north of New Zealand. TC Pam has weakened somewhat in the last 6 hours, therefore being downgraded to a category 4 cyclone and forecast to weaken to a category 3 cyclone overnight. Pam is expected to lie about 150km east of East Cape (northern Gisborne) by midday Monday.

Visible satellite image of tropical cyclone Pam (left). Visible satellite image of tropical cyclone Pam (left).
Rain radar (right) at 3pm Sunday 15 March 2015. Rain radar (right) at 3pm Sunday 15 March 2015.

The satellite image (left) shown above clearly shows thick cloud bands with embedded thunderstorms around the centre of the low producing heavy rain over the ocean north of New Zealand. Outer rain bands have spread over Northland and Auckland as seen in the above radar image (right).

 

Track of TC Pam. The orange lines mark the uncertainty of the track. Times are given in UTC, add 13 hours for New Zealand local time. Track of TC Pam. The orange lines mark the uncertainty of the track. Times are given in UTC, add 13 hours for New Zealand local time.

 

The latest analysis indicates that the system will remain classified as a tropical cyclone when it passes to the northeast of Gisborne by midday tomorrow with average wind speeds of up to 140km/h near the center of the low. Please refer to the latest severe weather warnings and watches issued by MetService for more information.

Sunday 15 March 2015 10:30am

FULONG LU, METSERVICE METEOROLOGIST

Satellite picture for the Tropics at 7am NZDT 15th March 2015 Satellite picture for the Tropics at 7am NZDT 15th March 2015
Track of TC Pam. The orange lines mark the uncertainty of the track. Times are given in UTC, add 13 hours for New Zealand local time. Track of TC Pam. The orange lines mark the uncertainty of the track. Times are given in UTC, add 13 hours for New Zealand local time.

Tropical Cyclone Pam (now Category 4) has moved across 25S into TCWC Wellington (MetService NZ) area of responsibility early this morning. At 7am today (Sunday 15 March), it was located at 26.8S 172.7E or 850 kilometres north of Cape Reinga, moving southeast 52 km/h. The storm has sustained winds of 205 km/h near the centre, with gales extending out to about 400 kilometres from the centre. On its southeast track, Tropical Cyclone Pam is expected to lie about 620 kilometres north-northeast of Cape Reinga at 1pm this afternoon, and about 420 kilometres north of East Cape at midnight tonight, and about 240 kilometres east of East Cape at midday Monday. Heavy rain and strong wind warnings and watches are in force for the northern and eastern parts of the North Island from this evening through to Tuesday.

Please refer to our warnings page for details at MetService warning home page.

Apart from heavy rain and severe gales, Tropical Cyclone Pam is expected to bring heavy swells to the North Island east coasts from Northland to Hawke’s Bay, with 4 to 6m near the coast, and 6 to 8m offshore. People considering venturing near or into the water, are advised to take extra precautions, especially when winds are onshore, and to check the latest forecasts for expected dangerous conditions.

Next update will be at or no later than 16:00 NZDT Sunday 15 March 2015.

Sunday 15 March 2015 5am

MATTHEW FORD, METSERVICE METEOROLOGIST

At 1am this morning (NZ local time) Severe Tropical Cyclone Pam was located over waters about 500km southeast of Noumea, New Caledonia, moving quickly south-southeast at 45 km/h. TC Pam is still a category 5 cyclone but has begun a weakening trend.

Infrared satellite image of tropical cyclone Pam, 3.44am Sun 15th March 2015 Infrared satellite image of tropical cyclone Pam, 3.44am Sun 15th March 2015

The above infrared satellite image of TC Pam is colour coded to show the temperature of the cloud tops. An eye is still clearly visible in the centre of the image, but the surrounding cloud tops, which are a band of intense thunderstorms, are not as cold as they were at this time yesterday (refer to yesterday's 5am blog update for a comparison). The green colour indicates the cloud top temperature of the thunderstorms surrounding the eye is about -65C, while this time yesterday they were -82C, suggesting that the cyclone has weakened. However, winds near the centre are still estimated to be over 200 km/h.

The latest track map issued by RSMC Nadi (below), shows TC Pam taking a southeast track to the north of New Zealand. As TC Pam moves southeast over cooler waters it should continue to weaken, but will still be an intense storm with hurricane force winds near the centre out to midnight tonight.

TC Pam forecast track map issued by RSMC Nadi 2.17am Sun 15 March 2015 TC Pam forecast track map issued by RSMC Nadi 2.17am Sun 15 March 2015

TC Pam has now moved into the Wellingon Tropical Cyclone Warning Centre area of responsibility, so future cyclone tracks will be issued by MetService. The system is expected to bring heavy rain, severe gales and high seas to parts of the North Island. Please refer to the latest severe weather warnings and watches issued by MetService for more information.