south west pacific Severe Tropical Cyclone Pam

[tropicbreeze]

A low is developing in the South Pacific east of the Solomons, north east of Vanuatu. Potential for development into a tropical cyclone within 24 to 48 hours is high.

At 1800 UTC central pressure 1000 hPa position South 8.4 East 169.0, movement south west at 3 knots, wind (10 minute) 20 knots, sea surface temperatures 30C.

TROPICAL CYCLONE THREAT TRACK MAP
Tropical Cyclone Warning Number 2 issued 1352 UTC Saturday 7 March 2015


GFS 156 hour forecast, Init. 00Z 20150307, valid at 12Z 20150313

[Somerset Squall]

Models have been pretty aggressive on the intensity of this system, as is reflected in that forecast. Could be a significant threat to Vanuatu, one to watch.

[tropicbreeze]

Yes, over the past week the models have had the track varying from directly over Vanuatu and along the chain of islands, or between Vanuatu and Fiji. Whichever track it does follow there will always be some islands directly affected.

[tropicbreeze]

11F has not changed much over the past 24 hours, vertical wind shear is low, sea surface temperatures 30C. It's expected to develop into a tropical cyclone in 12 hours.

At 08/1800 UTC central pressure 999 hPa position South 7.9 East 168.5, movement north west at 2 knots, wind (10 minute) 25 knots.
 

[tropicbreeze]

Organisation has improved and vertical wind shear is still low.

At 09/0000 UTC central pressure 997 hPa position South 8.2 East 169.4, movement south at 2 knots, wind (10 minute) 30 knots.

Colourised Infrared satellite imagery 20150308 1932 UTC

[Somerset Squall]

Fiji Met and JTWC have upgraded the system to Tropical Cyclone status, with winds of 35kts. Pam has a large area of very deep convection obscuring the LLCC, with banding features also evident. A building ridge to the east will drive Pam southwards over the coming days, between Vanuatu and Fiji. As Pam heads south, it will find lower shear and greatly enhanced outflow, particularly in a poleward direction as it links up with the mid-lattitude westerlies. JTWC expect a peak of 120kts before shear eventually rises due to the westerlies further south.

[Somerset Squall]

Pam is strenthening quickly, with 1 min sustained winds now at 55kts. Pam had developed a central dense overcast with very strong banding in the northern quadrant. Further strengthening, perhaps rapid, is expected as Pam moves generally south.

[Sainsbo]

Definitely one to watch. The models are still forecasting some rediculously low minimum pressure readings from Pam. (874mb on the GFS 6z, ).

[Chris W]

After a quiet SW Pacific cyclone season we are watching this one closely. Looks certain to impact Vanuatu, possibly as a Category 4, maybe New Caledonia and then recurve just east of NZ when extratropical - although the North Island may get a good deal of (much-needed) rain pushed in from the east.

We will see. Hang in there Vanuatu.

[Somerset Squall]

Winds are now up to 80kts according to JTWC. They expect a cat 5 peak on the SS scale, with winds of 140kts.

[Somerset Squall]

Pam continues to intensify quickly, winds are now at 90kts (cat 2 SS scale) according to JTWC. Pam has a solid central dense overcast, from which an eye looks to he forming.

[Chris W]

SSTs have been high around NZ of late, wondering how far south this will retain TC status for.  Currently Pam is in an environment of 29C SSTs and as Somerset Squall as mentioned forecast to peak at Cat 5/140kt sustained (170kt gust) just east of Vanuatu inside 48 hours with a 165nm radius of 34kt winds.

 

Current threat map from Fiji Met, showing the threat to the Vanuatu islands - particularly Vila and Tanna on the current forecast track:

 

 

 

 

 

[Somerset Squall]

Pam is now a cat 3 on the SS scale, with winds of 105kts. The eye is developing nicely, but the majority of the convection is still located in the northern quadrant of the cyclone. There is moderate shear over Pam, but this is being easily offset by robust radial outflow. Therefore, particularly as shear is expected to ease soon, Pam should continue intensifying, perhaps rapidly. Unfortunately, Pam has also been jogging west of due south, and therefore the track forecast has shifted in this direction, which places Vanuatu in a much more dangerous position.

[Somerset Squall]

Pam looking much more symmetrical now, with the eye clearing out and being more central to the CDO. Winds are up to 115kts (1-min sustained), which is a cat 4 on the SS scale.

[Sainsbo]

12z GFS for Pam..

 

 

While I don't ever trust the models when it comes to the intensity of Tropical Systems, if this were to verify, it would beat the record that Super TyphoonTip set over 30 years ago.

 

Luckily dry air incursion has kept intensification slower than expected so far, but that may not last much longer.

[Chris W]

Pam at 941hPa this morning.  JTWC expect a minimum pressure of 907hPa.

 

http://www.meteo.gov.vu/TropicalCyclones/Warning/tabid/172/Default.aspx

http://www.meteo.gov.vu/TropicalCyclones/TCTrackMap/tabid/173/Default.aspx

 

Westward revision of the track by UKMO also leads to this on Tuesday:

 

[knocker]

may be the first Cat. 5 in SW Pacific in 5 years. Threat to #Vanuatu: http://wxch.nl/1BzgXE2 

[Somerset Squall]

Pam is on the verge of becoming a cat 5 on the SS scale, with winds now at 135kts, the very high end of cat 4. The eye has become much better defined this morning. JTWC expect a peak of 150kts.

[Chris W]

Pam is being reported by NZ media as having reached category 5 status (no official confirmation as yet), pressure 920hPa and a very clear eye now.

 

http://www.stuff.co.nz/world/south-pacific/67314645/tropical-cyclone-pam-becomes-category-5-supercyclone

 

http://phys.org/news/2015-03-tropical-cyclone-pam-nasa-eye-opening.html

 

 

 

 

 

 

[Somerset Squall]

Yep, it's been a cat 5 on the Australian scale all afternoon, but it has now achieved cat 5 status on the SS scale too, with 1-min sustained winds now at 140kts. Further strengthening is likely, just how strong will this monster get I wonder?

[knocker]

Category 5 Cyclone Pam Bearing Down on Island Nation of Vanuatu

 

Residents of the South Pacific island nation of Vanuatu are bracing for the impact of Category 5 Tropical Cyclone Pam, one of the strongest tropical cyclones ever recorded in the waters east of Australia. Pam has rapidly intensified over the past two days and reached top sustained winds of 160 mph as of 2 pm EDT Thursday, making it one of only ten Category 5 storms ever recorded in the basin since satellite records began in 1970. The official tropical cyclone warning center for the area, the Fiji Meteorological Service, estimated that Pam had a central pressure of 918 mb at 2 pm EDT Thursday.

http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2933

[Chris W]

At 7am NZST (18:00 GMT Thursday) Pam had winds of 257kmh with top gusts of 314kmh (Weather Undergroound).  That is serious.  The eyewall is now impacting/very close to Vanuatu's north-eastern islands and the eye is very well protected.

 

 

[Somerset Squall]

This is a scary image for Vanuatu:

Winds are now at 145kts (1 min sustained).

[Sainsbo]

Looks like a bit more than 145kts to me. (Many people commenting on Twitter that CIMSS is showing T7.5 ~175-180mph) I really hope people have taken the necessary precautions, it looks like it's going to be rough.

 

[Chris W]

Vanuatu is one of the poorest nations in the world, this will hit them very hard.  UNICEF and Red Cross (amongst othes of course) are already doing what they can and will need donations to support recovery work for sure.  It's rare to get something this strong in the SW Pacific by all accounts, but the conditions were there with high pressure forcing convection to group into a big system and head south.

 

We already have an outlook for severe gales and heavy rain over the North Island and eastern South Island for Monday through Wednesday, but before Pam gets anywhere near here it's our island friends who are feeling her fullest force.