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Somerset Squall

Tropical Cyclone Funa

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Tropical Cyclone Funa has formed in the South Pacific. It is located 740 nautical miles north of Nadi, Fiji, and is tracking northeastwards in response to ridging to the northwest. It is expected to turn on a more eastwards track beyond 36hr due to the ridge building to the north. Conditions are favourable for intensification from it's initial intensity of 35kts.

Funa is quite a large system and will bring heavy rains to Vanuatu in the next 24-26hrs as it scrapes nearby. Funa will clear Vanuatu and continue to strengthen. Funa isn't expected to be all that strong once it gets into the vicinity of Vanuatu and rainfall will probably be the main problem. Something that needs to be watched.

Satellite image of Funa: (top-right portion of pic, also worth noting a tropical low trying to develop over Australia, but unless it moves over water chances are tiny)

xxirgms5e.GIF

Taken from CIMSS

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Big system Funa is which would suggest that its going to be a slow developer, esp given condtions aren't stunning right now, though the shear profile and sst's do look good enough for modest development before it starts to head to the south and into lower heat content which will weaken the convection and weaken the system. Before then though I would not be at all surprised to see the system to reach 65-70kts before it starts to weaken though as I said before its likely to be steady rather then raid development given the very sizeable convective coverage. Saying that I don't know the size of he circulation which may be less massive and thus allow slightly faster development.

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Storm Alert issued at 16 Jan, 2008 6:00 GMT

Tropical Storm FUNA is forecast to strike land to the following likelihood(s) at the given lead time(s):

Yellow Alert Country(s) or Province(s)

Vanuatu

probability for TS is 65% in about 24 hours

Yellow Alert City(s) and Town(s)

Taktak (14.9 S, 166.6 E)

probability for TS is 60% within 12 hours

Foreas (13.9 S, 167.5 E)

probability for TS is 55% in about 24 hours

Onetar (14.3 S, 167.4 E)

probability for TS is 55% in about 24 hours

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According to JTWC, Funa as intensified fairly quickly to 55kts. Like you say KW, I wasn't expecting it to strengthen that much by this advisory due to it's size. JTWC indicate continued strengthening due to excellent outflow and a favourable upper level environment- with an intensity of 85kts forecast by 48hr. Vanuatu is currently getting a soaking and because the system is large then rainfall totals will be very high- any estimates on how much could fall KW? The island will also be battered by damaging winds as Funa is strengthening at a fair pace and won't clear the island for at least another 36hrs. Funa's easterly track will change to a southeasterly motion after 24hr.

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I noticed from one alert to the next how gone from yellow to red.

Storm Alert issued at 16 Jan, 2008 18:00 GMT

Tropical Storm FUNA is forecast to strike land to the following likelihood(s) at the given lead time(s):

Red Alert Country(s) or Province(s)

Vanuatu

probability for CAT 1 or above is 50% within 12 hours

probability for TS is 95% currently

Red Alert City(s) and Town(s)

Tasmaori (14.9 S, 168.1 E)

probability for CAT 1 or above is 50% within 12 hours

probability for TS is 90% within 12 hours

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Funa has continued strengthening and is now at 65kt (equivalent to a minimal cat 1 hurricane on the SS scale) tropical cyclone. It is now tracking east-southeastwards after crossing Vanuatu. Some really warm waters lie ahead of the cyclone and due to favourable upper level winds and excellent outflow, Funa has potential for further (the JTWC even suggest rapid) intensification. The JTWC are estimating a peak of 100kts before Funa continues south into cooler waters by 48hrs which should induce weakening. It looks as if the ingredients are there for a fairly potent storm.

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Thanks for the good update mate :)

Storm Alert issued at 17 Jan, 2008 6:00 GMT

Tropical Cyclone FUNA is forecast to strike land to the following likelihood(s) at the given lead time(s):

Yellow Alert Country(s) or Province(s)

Vanuatu

probability for CAT 1 or above is 10% currently

probability for TS is 85% currently

Yellow Alert City(s) and Town(s)

Tasmaori (14.9 S, 168.1 E)

probability for TS is 75% currently

Green Alert City(s) and Town(s)

Lamen (16.6 S, 168.2 E)

probability for TS is 50% currently

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I still don't think Funa under going anything more rapid then steady development due to its size and its convective coverage is a little messy...though bigger systems do tend to be like that until they reach around 100kts then they tend to get the classic look esp where heat content is pretty high like we presently. Ironically it may start to look its best as it starts to head into lower heat content and as the system starts to reach higher into its MPI (maxinum potential intensity) as it dives to the SSE and its outflow channels get a boost, this will likely be when Funa reches its max strength.

Funa does have some pretty impressive convection even if its not amazingly well organised. Current Sat estimates place this system around 60-65kts which looks about right I'd guess.

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Funa has continued intensifiying and is now at 80kts. Funa has about 24hrs of favourable condtions before SST's begin to fall away as the storm moves briskly southwards. Track speeds are now forecast to be faster which is the reason why the storm will move over cooler waters a little earlier than previously thought. Funa is curently heading south-southeastwards but a more southerly motion is anticipated to kick in by 24hr, with possibly a southwestward turn by 36hrs in response to a trough near New Zealand. This will bring Funa over even cooler waters and extratropical transition should begin to occur. Funa is likely to be a fairly potent extratropical storm by about 48hrs.

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Still looking good Funa is, as I said yesterday Funa is starting to take on a classic look as it reaches 90-100kts, NRL estimates the system at 90kts and 956mbs it appears and whilst sat estimates are a little lower. Eye looks like its beenfilling over the last few hours maybe a sign of slightly lower area of heat content its starting to head towards...indeed heat content drops away pretty rapidly in Funas path over the next 24hrs and this should mean that the cnvection will become more shallow in nature around the system and whilst it may look a little better again over the next 12hrs. After its reached as high as its MPI will allow it to it'll start to decay and thats when the system will begin to weaken.

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Indeed Cookie, it's shows that Funa has intensified significantly this afternoon, the JTWC have the initial intensity set at 105kt. The remainder of the forecast is basically unchanged; Funa has pretty much reached it's peak (JTWC expect 110kts to be the peak) and will continue to push southwards pretty quickly taking it over significantly cooler waters, and, due to this and interaction with a trough to the southwest, should induce extratropical transition from 24hrs. Funa is expected to become a powerful extratropical storm in the vicinity of New Zealand.

BTW, what does the JTWC mean by this?

THE CYCLONE HAS INTENSIFIED CONSIDERABLY OVER THE

LAST 12 HOURS, WITH CURRENT SATELLITE-DERIVED ESTIMATES SUPPORTING AN

INITIAL INTENSITY OF 105 KNOTS. MOREOVER, THE CYCLONE NOW HAS A 24-NM

IRREGULAR EYE EVIDENT IN RECENT INFRARED IMAGERY.

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As it happens Funa is looking very impressive over the last few hours and I'd guess its still etting tornger right now, don't be surprised if it gets upto 110-115kts tonight. As I said ealrier as it starts to head into lower heat content it is going to start looking more and more impressive as the waters start to suppot lower MPI (max potential intensity) and as the system stays even yet the MPI decreases thus the gap between the two becomes less and so you get a better looking storm...hence why in the tropics sometimes you won't get a decent eye till cat-3 yet in themore northern latitudes evn cat-1 hurricanes have decent looking eyes.

As for irregular eyes, it simply means that its not very well shaped, in other word its shape is at times irregular and thats a feature usually of weakening systems...I suspect it has something to do with the heat content decreasing...for now the decent outflow plus the decaresing MPI is given the system a shot term boost IMO.

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Thanks for that KW. Also, a great explanation about MPI and how a storm looks, I have learnt something new today :) . Great to have your input in these threads mate.

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The best way to gauge MPI is probably how deep the convection is. If there is a lot of heat content then your far more likely to see very cold cloud tops despite upper temps being higher in the deep tropics. If you look at IR for example with a deep tropical system which is strong then cmpared a system of the same strength further north you'll notice the dfference in the depth of convection and thus the cloud top temps.

It's all very complex and I'm sure there are factors I don't know about!

btw there are MPI charts out there but take note that many other factors prevent a system getting upto its MPI...Wilma in 05 got pretty close I see to recall as do Annular storms if I recall correctly?!

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is that quite a recent image? I couldn't tell

https://metocph.nmci.navy.mil/jtwc.php

Yeah, quite recent, 5.30pm. Shows the "irregular" eye pretty well. The image I posted in the first post refreshes itself, I have no idea how often though.

Blimey, I think it just has refreshed. Funa looking even more impressive in the latest image. I shouldn't be surprised really, Kold said it would :D

It's all very complex and I'm sure there are factors I don't know about!

btw there are MPI charts out there but take note that many other factors prevent a system getting upto its MPI...Wilma in 05 got pretty close I see to recall as do Annular storms if I recall correctly?!

I'm sure it is Kold :lol: . Interesting stuff as complicated as it is though. Would surface pressures in the area of the storm be another factor that influences MPI or would it make no difference?

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The view from New Zealand:

Metservice say:

Situation for all New Zealand issued at 07:42am Saturday 19-Jan-2008

A ridge of high pressure lies over the South Island, and a tropical cyclone Funa just southwest of Fiji moves southwards, giving strong easterly winds over the North Island today and tomorrow.

The newspaper forecast today mentioned "some uncertainty" in the track, but likely to move southwards and to the West of New Zealand, and weaken. Then to weaken further as it crosses the central North Island on Tuesday/Wednesday.

AFAIK, the SSTs around NZ right now are at a maximum of about 21-22C.

Lots of people hoping for rain from this, hopefully it won't be too destructive though.

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I'm sure it is Kold :lol: . Interesting stuff as complicated as it is though. Would surface pressures in the area of the storm be another factor that influences MPI or would it make no difference?

I'd think it does have a role to play though I think it tends to allow slightly deeper pressures to be reached. A great example of this was the 05 season. That season saw an area of lower pressure in the Caribbean and the Gulf of Mexico to do with an extended monsonal trough which isn't a very common feature I believe. This feature is also usually found in W.Pac and thats why you can get such deep pressures as well as so many storms in that basin...the 05 seaso effectivly acted like a W.Pac season hence the huge numbers of storms and 4 category-5's as well as the lowest central pressure recorded, the fact that ambient pressures in the caribbean were low to start with that alowed systems to dig down deeper in terms of pressure then you'd see in other years....hence why3 out of the top deepest pressures recorded come from the 2005 season.

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Storm Alert issued at 19 Jan, 2008 6:00 GMT

Intense Tropical Cyclone FUNA is forecast to strike land to the following likelihood(s) at the given lead time(s):

Yellow Alert Country(s) or Province(s)

Norfolk Island

probability for CAT 1 or above is 10% in about 36 hours

probability for TS is 50% in about 36 hours

Yellow Alert City(s) and Town(s)

Kingston (29.1 S, 168.0 E)

probability for CAT 1 or above is 10% in about 36 hours

probability for TS is 50% in about 36 hours

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Thanks KW, i never knew a monsoonal trough was located there in 2005, as you say, monsoonal troughs are why so many storms are spawned in the West Pacific. I remember reading that surface pressures were particularly low in the region Wilma was in, hence the 882mb reading. That's what made me think perhaps surface pressures were another thing that influences MPI.

Anyway, according to JTWC, Funa has held intensity over the last 12 hours, and remains impressive on satellite imagery. However, excellent outflow won't be able to sustain the system for long, and that's the only thing Funa really has on it's side at the moment. Waters are cool beneath the storm now and shelve off pretty steeply on it's general southerly motion. Extratropical transition is expected to commence in 24hrs and be fully completed within 48hrs. As I have been saying before, Funa will be a pretty deep extratropical system passing just west of New Zealand in about 72hrs time, and as Cookie's alert indicates (thanks Cookie) it could give tropical storm force winds, maybe even CAT 1 winds and some heavy rain I would imagine.

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Funa has weakened considerably over the past 12 hours, down to 75kts according to the JTWC. They also have track speed at 23kts, which is faster than previously. This will mean extratropical transition will begin sooner, possibly within the next 12 hrs, and will be completed by 24hrs. Extratropical Funa will then move southwestwards to the west of New Zealand, where it could bring some lively weather.

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final storm alert

Storm Alert issued at 20 Jan, 2008 6:00 GMT (Final Warning)

Tropical Storm FUNA is forecast to strike land to the following likelihood(s) at the given lead time(s):

Yellow Alert Country(s) or Province(s)

Norfolk Island

probability for TS is 65% within 12 hours

Yellow Alert City(s) and Town(s)

Kingston (29.1 S, 168.0 E)

probability for TS is 60% within 12 hours

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NZ going to have strong NW winds and heavy rain tomorrow due to ex-Funa. High humidity and warm temperatures making it fairly uncomfortable. Reports of air temps hitting 30C and dewpoints of 20C in places, with higher dewpoints (up to 23C) and lower temperatures further north. The sooner this thing moves on its merry way and brings back some fresher winds the better!

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