The Tropical March Begins
Over the coming fortnight, the formation of at least one - if not a couple - swell-producing systems looks almost certain in the Coral and Tasman Seas.
The catalyst for the storms will be increasing tropical activity to our east-northeast into the end of the month.
The increased convection and instability will be linked to the strengthening Madden Julian Oscillation (MJO). The MJO is, in effect, a wave of increased tropical activity and convection that propagates east along the equator.
Also, sea surface temperatures are primed in the Coral Sea for the formation of a tropical cyclone (well above the required 26.5C), as well as a lack of strong upper atmospheric winds (that create wind shear) forecast for the start of March.
Chance of tropical storm formation (%) for the period Sunday 26th February to Sunday 5th March (ECMWF)
This bodes well for northern NSW and south-east Queensland surfers in regards to swell potential, but of greater interest is what's taking place in the Tasman Sea.
The East Australian Current has been sending significant plumes of warm water down the East Coast towards southern NSW.
Sea surface temperatures in the middle of the EAC are now 26-27°C off of Seal Rocks, with water temperatures off Jervis Bay coming in around 25°C - which is 2-3°C above average.
Warm water brings with it stored potential energy which enhances and feeds into any instability that forms adjacent to the coast or offshore. Take for example the flooding downpours seen across the Shoalhaven region a fortnight ago, and the Northern Beaches earlier this week.
While it's too early to forecast the track or movement of any potential tropical cyclone/storm from the Coral Sea, the leading global forecast models are in general agreement regarding the movement of any tropical disturbance that may form, plotting a southward path towards the Tasman Sea.
A couple of pools of cold air are also forecast to be transported up from the Southern Ocean, across the south-east of the country during the start of March. These will sit above the warm water signal sitting off the southern NSW coast and could be the catalyst for the development of a more significant low.
There's no guarantee of great waves or large swell, or even the development of such a low in the Tasman Sea, but we'll be entering an unstable and dynamic period with plenty of potential thanks to the combination of warm, unstable air and cooler air aloft.
So be prepared to ride the long-range model forecast fluctuations and keep an eye on the regional Forecaster Notes over the coming weeks.
Comments
I'm excited ...
Since the last cyclone swell .. the banks are terrible..( waves have been shithouse as well ) fingers crossed for this potential swell forecasts
Scary
Surfs up, means crowds may... thin out.
Those crocodiles & Irukandji drifting down the coast could spoil a good Qld surf though,
https://en.wikipedia.org/wiki/Irukandji_jellyfish
https://www.sydney.edu.au/news-opinion/news/2019/05/01/pain-researchers-...
(& ...covert a hardcore hedonist to some deity asap)
https://www.dictionary.com/browse/deity
Dust off the big board & take a spare legrope... those tradewind lines look long.....
P.S. Metvuw models shows a cyclone moving directly over New Caledonia next Friday..... I hope these models are off.
Notice over the next few days, the eastern side of a 1042 High over China, augmenting the NE trades in the South China Sea, to create an extra burst of moist wind feeding into the tropical W-NW Monsoon tradewind belt above Australia. To the south of that, off the NW WA coast, winds rotating around a low pressure system there will be adding to and thus further increasing that W-NW wind flow.
That strengthening of the W-NW monsoon wind will then feed all of that moist tropical air across through the Arafura and Timor Seas and into the Coral Sea, where it will run into the NE trades feeding in from the north of the monsoon trough, and the SE trades feeding into it from the south. The rotation from the 3 coming together there in the Coral Sea, will set off that circulation of hot, tropical, rising air.
BOM also mentions a strengthening of the MJO over the Western Pacific coming up as we head into the end of February too, so combine all of that extra convection and instability and moist tropical rising air, and a tropical revolving storm doesn't really come as a surprise. Are you seeing similar Craig?
Actually ... reminds me of commercial fishing on the outer GBR off the Far North Qld Coast through the cyclone seasons decades ago. As the monsoon trough would become 'active', we would start seeing a mass of huge dark scud clouds and squalls build up around us. It was pretty eerie actually. That was the indicator to go north towards the Torres Straits, above the trough line and out of harms way, before something set in. Sitting in a 19' fibreglass dinghy one afternoon, around 40nm offshore and maybe a similar distance SE of Cape York from memory, but still within the outer 'barrier' reef edge, I remember seeing 4 full raging waterspouts simultaneously, all pouring out of one big single dark scud cloud.
Cyclones can build up quickly and without warning, and especially years ago before better forecasting technology. We saw plenty of E coast lows and tropical lows and isolated storms and squalls form up, that the Met Bureau only mentioned AFTER they formed. Have seen lots of gales and lows and severe winds form in multiples of different oceans that the local met offices neither predict, nor even bother to mention after they have formed up.
JodyP. Interesting stuff. Thanks.AW.
Thats interesting that you would go north to get above the trough line.
Several reasons:
1. I believe the islands of the Torres Straits generally do not get cyclones. Close either side and to the south yes, but seems like a little window there that is clear.
2. Cyclones in that area generally dont travel north above that trough line. If you were to the south of it and it forms and matures, you stand that chance of it coming over you.
3. If you were to the south of it, or even to the west or east, that could also put you in the 'dangerous quadrant' of the cyclone, in an area of often much stronger winds and much bigger seas.
4. If you get a large high pressure system underneath (to the south of) the cyclone you not only get the cyclone winds, but the winds off the high underneath as well ... the 'squeeze'. That can add strong to gale force winds and a far larger fetch and much bigger waves and swell, for hundreds of miles south, underneath the cyclone.
5. There can be almost a vaccuum behind a cyclone as it moves. So a cyclone forming up up there and then moving south'ish, you do not have to be far away to be out of the strong winds.
6. There are some excellent cyclone havens / cyclone anchorages further north, and you have to have thise close by and in mind if anticipating the possibility of any strong wind. Escape River, just south of Cape York was a favourite for any strong winds - including when huge winter high pressure systems augment the normal winter trades.
And that Far northern Qld and Torres Straits area has, I believe, some of the strongest and most prolongued winter trade winds in the world. We fished it one time for three and a half months starting in April. Six days of nice weather at the start, then the entire rest of the time nothing under a strong wind warning.
* On that note something of a rule of thumb I have found in tradewind areas around the world. Whatever the central pressure of the high pressure system in hectopascals, take the last 2 digits, minus 5-10, use that as an estimate of expected wind strength. Example, 1030 high gives you 20-25 knots. 1040 high gives you 30-35knots. If there is a slight trough 'squeezing' the top of the high, add maybe 20%.
Is that you Jody Perry?
Yep.
Thanks Jody, yeah moisture in-feeding from both the west-northwest and east-northeast, all converging in the Western Pacific.
Most of the activity looks to be forming a touch too far east than ideal for swell potential at this stage. But this will be a prolongoged period of tropical activity.
What are the chances of NZ getting hammered by another cyclone? Shocked at what happened in Hawkes Bay
Indeed global models are beginning to look juicer for the coral sea by late this month aswell.
I would not like to speculate Spinafex, but we are in the middle of cyclone season and models are showing a system tracking south through the South Pacific slot.
Both EC and GFS not forecasting great swell production from this tropical development out near Fiji. The compact nature and fairly rapid movement to the SE once it pokes below New Cal and into our swell window all points to nothing of huge size or substance from this one at present. Cradling high and slower movement or even better a westward retrograde and that could make me smile.
No, the initial developments aren't ideal.
Each successive model run progs less and less swell potential.
yeah its got so much potential, but i feel we are going to miss out.
Yep, there'll be swell, fun in size but overall nothing too significant now.
Looks like there'll be a decent frontal progression pushing up across the south-east of the country to follow, but a little after the major tropical developments.
I imagine all that moisture feeding in from South China Sea will take a while to get to the Coral Sea. I wonder if the setup might be ripe in a couple of weeks once the Gabrielle track warms back up again.
As is often the case with tropical activity.... downgrade... downgrade...downgrade. Unfortunately no catchers mitt, and a conga line to the graveyard.
yep.
need a better catchers mitt.
Ha, good terminology!
That tropical disturbance progged on the long range charts up in the NT is an interesting one to watch over the coming weeks!!!
Catcher’s mitt creeping into place as well
And Judge Judy enters the room. Tropical Cyclone Judy that is.
Looks like a bad time for Port Vila.
PV in for another round with Kevin
looks more like a mid-winter cold anom for down south. Would be some weather in that shortwave as well if the model verifies.
Yep, big slow moving gyre.
Autumn coming with a bang for our SE friends.
Also a little more wow factor with control en sniffing a decent cradled cutoff cruiser, a tad more march madness.
I'm def liking the looks of the long range model setup from the Coral Sea stretching out into the Tropical South Pacific (TSP). LOTS of potential in that long elongated monsoon trough right from the top end out into the TSP. Watch this space I say.
Looks like the Tasman Sea might steal our thunder now!!!
I get nervous when I see that N'ly orientation of the high pressure belt.
4 days in a row with winds with an N in front of them is not what I want to see in March.
Thats a Spring type pattern.
Yes super unseasonal.
Might need to re-energise the season reversal article.
SST's have dropped 6 degrees on the Byron Buoy after 4 days of N'lies!
From 27 to 21.
Surfed in straight boardies and lovely and refreshing for a change.
Really felt that temp drop yesty arvo, paddled out in boardies and it was freeziing compared to few days ago. Lasted about 45mins, woulda gone longer if the waves were better
Here's the latest data..
GFS 00Z was not doing the island chain any favors with another cyclone in the region. Still early i know. The wedged between ridges with no steering and just meandering is not a good scenario. Better to get a fast mover.
What about for the West coast Craig?
GFS sniffing a heavy a precipitation period. For some central tableland regions.
Just a heads up for anyone who may have to travel that way in the said timeframe.