Welcome Tropical Cyclone Sarai

Ben Matson
Swellnet Analysis

Overnight, the RSMC Nadi Tropical Cyclone Centre in Fiji announced that a tropical depression had intensified to tropical cyclone strength. It has been named TC Sarai.

TC Sarai is the second tropical cyclone of the 2019–20 South Pacific cyclone season, which begins on November 1st. Severe Tropical Cyclone Rita was named on November 24th though remained outside of our swell window. 

The genesis of TC Sarai took place north of Vanuatu on December 23rd, near the Santa Cruz Islands. Over the following days, a developing area of low pressure became more organised and by Christmas Day was considered a tropical depression, before reaching the lower thresholds of a Tropical Cyclone late on Boxing Day. 

TC Sarai is still postioned north of Fiji, and the Australian East Coast currently lies within the swell shadow of Vanuatu, New Caledonia and Fiji. However, TC Sarai is on a slow southward track and is expected to push into our swell window later today or tomorrow as it strengthens to Category 2 status. It will then begin generating swell for South-east Queensland, New South Wales and Eastern Tasmania.

At this stage, despite the reasonable distance between TC Sarai and the mainland, and the expectation that it will move slowly towards the east - both factors that can significantly temper the swell outlook - we are still anticipating a strong E'ly thru' E/NE groundswell next week, persisting for several days thanks to TC Sarai's lengthy duration within the swell window.

There is however concern as to the local winds and subsequent surf quality as the swell makes landfall. This is covered more comprehensively in your detailed Forecaster Notes. 

Comments

Numbatt's picture
Numbatt's picture
Numbatt commented Friday, 27 Dec 2019 at 8:54am

Will it rain?

thermalben's picture
thermalben's picture
thermalben commented Friday, 27 Dec 2019 at 9:23am

Where?

It'll eventually rain everywhere.

As for rain associated with TC Sansai: Fiji, Tonga and maybe Samoa are at risk of significant totals.

But it'll have no direct influence on rainfall anywhere in Australia.

freeride76's picture
freeride76's picture
freeride76 commented Friday, 27 Dec 2019 at 9:53am

this one is going to be a real mystery bag, takes the wrong turn at almost the precise moment it enters the swell window, quite a strong little system but no supporting high, meanders off directly opposite to the direction of the circle path, possible blocking effects from islands between Fiji and Tonga.

good luck putting numbers on that one.

donweather's picture
donweather's picture
donweather commented Friday, 27 Dec 2019 at 10:58am

Doesn’t really matter Steve as we have Fcking shit winds for the entire duration of this swell anyway.

thermalben's picture
thermalben's picture
thermalben commented Friday, 27 Dec 2019 at 11:37am

Isn't the technical term "jellyfish shit winds"? I recall Sheepdog using that term a while back. The description always sounded bang on.

Craig's picture
Craig's picture
Craig commented Friday, 27 Dec 2019 at 11:39am

Haha.

freeride76's picture
freeride76's picture
freeride76 commented Friday, 27 Dec 2019 at 12:41pm

I'm not so sure about the winds Don.

v. warm SST's inshore at the moment can over-ride a lot of synoptic effects.

as has been happening the last few days.

but I very much doubt we'll get a "strong E'ly thru' E/NE groundswell next week".

I reckon we'll get a very flukey, super incon. highly tidally influenced 3-4ft swell.

Spuddups's picture
Spuddups's picture
Spuddups commented Friday, 27 Dec 2019 at 2:52pm

The latest model from Windy has it hardly moving at all then petering out just below Fiji. Looks to me like the bulk of the swell energy will be heading towards The Solomons. Should send something to Australia though. The NE coast of NZ looks like it might even do a bit better out of it than Australia. Unlike the Cricket at the moment where you guys are giving us a farken’ towelling!

topgeer's picture
topgeer's picture
topgeer commented Monday, 30 Dec 2019 at 9:28am

NZ Ne coastline will get nothing from this TC due to no significant fetch point this way, but more importantly there is no captured fetch as the TC is moving away to the E and then NE... the optimal swells from a TC are either from the captured fetch as it moves towards your location or if if drops onto a high and the fetch then points towards you... will have to wait for the next one.

Spuddups's picture
Spuddups's picture
Spuddups commented Monday, 30 Dec 2019 at 10:16am

Cheers man, something for me to think about.

truebluebasher's picture
truebluebasher's picture
truebluebasher commented Sunday, 29 Dec 2019 at 9:05am

https://higginsstormchasing.com/2019-20-tropical-cyclone-outlook-austral...

https://www.newsport.com.au/2019/october/fewer-cyclones-predicted-for-up...

WA Current outlook...
Bom outlook for Karratha is mod winds > increase rains thunderstorm
http://www.bom.gov.au/wa/forecasts/karratha.shtml

BOM Karratha 3rd Jan charts show moderate 30km / hr 'clockwise winds'.
http://www.bom.gov.au/australia/meteye/

Cyclone?
Windy TV shows TC build NYE & slam Karratha next Friday 3rd Jan 2020 .
Fires up fast & hits hard, unusually drives deep inshore to bring western cockies rain.
Only hypothetical at this stage...as said BOM aren't taking the bait...(Cyclone Watch!)
https://www.windy.com/?2020-01-02-12,-15.623,126.519,5

(update) Fizzer by windy TV > BOM-light clockwise winds was the right call...

thermalben's picture
thermalben's picture
thermalben commented Saturday, 28 Dec 2019 at 12:58pm

The Mamanucas are getting smashed.

topgeer's picture
topgeer's picture
topgeer commented Sunday, 29 Dec 2019 at 10:15am

Nice flyover by Ascat... cannt see any Jason3 activity yet!

donweather's picture
donweather's picture
donweather commented Monday, 30 Dec 2019 at 8:41am
thermalben's picture
thermalben's picture
thermalben commented Monday, 30 Dec 2019 at 8:48am

Altimetry data is overrated IMO. Hsig means nothing without direction and period.

Of course, it's useful to validate the wave model but ultimately I don't think - from a long range surf forecasting perspective - the accuracy of regional Hsig values have ever been a concern (unless they're very close to a coast that you're forecasting for).

Still, as a data nerd I'll happily look up anything to help pain the bigger picture. CIMSS winds, for example. 

donweather's picture
donweather's picture
donweather commented Monday, 30 Dec 2019 at 9:01am

It’s the best we’ve got to validate swells from TC compact fetches IMO particularly where islands/reefs may impact upon the swell generation that ascat passes can’t tell you about.

And when there’s only one swell in the water direction isn’t that important to record. But yes swell period would be nice if we could capture that remotely also.

thermalben's picture
thermalben's picture
thermalben commented Monday, 30 Dec 2019 at 11:49am

Too often they miss the most useful parts of the swell source. And if you've got two swell trains in the water - say, 1.5m of easterly trade swell and 1m of long period southerly swell - how do you know whether it's accurately picking up the relevant swell you're tracking?

I suppose to put it another way - what are the error margins you're looking for with TC Sansai right now? What kind of Jason 3 data reading would make you upgrade or downgrade a forecast?

That's just my personal opinion though. I've seen other forecasters reference particular oceanographic parameters that don't make a lot of sense to me. But.. as long as the forecast is useful, then it doesn't necessarily matter how you get there!

topgeer's picture
topgeer's picture
topgeer commented Monday, 30 Dec 2019 at 1:00pm

The Stormsurf Hindcast is just another tool in the bag, your points are valid about multiple swells and lack of period data..hence best to look at the model like BW detailed swell and then try to validaye or confirm by using ASCAT, Jason, WW3, etc.... until we have Buoys everywhere we will have to continue relying on the eyeball (at the beach).

donweather's picture
donweather's picture
donweather commented Monday, 30 Dec 2019 at 1:32pm

I agree Ben about the multiple swells. But as I said. With absolutely no other data to check open ocean swells it’s altimetry or nothing.

topgeer's picture
topgeer's picture
topgeer commented Monday, 30 Dec 2019 at 10:26am

I agree, altimetry is pretty average and hit/miss, but with no buoys in the water we have to use something else besides super computer forecast and model!

benjis babe's picture
benjis babe's picture
benjis babe commented Sunday, 29 Dec 2019 at 9:03am

it would be nice if we could get some swell when its not xmas or easter

donweather's picture
donweather's picture
donweather commented Sunday, 29 Dec 2019 at 9:47am

It would be nice if we could get some swell without fcking shit winds!!!

freeride76's picture
freeride76's picture
freeride76 commented Sunday, 29 Dec 2019 at 10:10am

you take the cyclone out of the picture and the progged MSLP charts show we are still balls deep in the negative SAM/SSW pattern.

weak, mobile high pressure in the Tasman at sub-tropical (not temperate, summer lats) leading to entrenched northerly winds with cold fronts in the lower Tasman.

will this pattern hold through summer like last summer?

there's probably enough juice in the current inshore Bluewater to stave off nuclear strength nor-easters for one, maybe two days. Then, once the upwelling and Ekman transport takes hold it'll be back to black.

donweather's picture
donweather's picture
donweather commented Monday, 30 Dec 2019 at 8:34am

I’m hearing ya Steve. Models have relentless Nly winds for over 8-9 days forecast for our area also. This is just bullshit for January!!!

topgeer's picture
topgeer's picture
topgeer commented Sunday, 29 Dec 2019 at 10:18am

Models are showing swell, but thye havent been able to fully work it all out yet... the TC is moving away on a steering ridge to the N and the only significant fetch is the SE (pointing to Solomons), I doubt we will see much decent swell off this one!

freeride76's picture
freeride76's picture
freeride76 commented Sunday, 29 Dec 2019 at 10:25am

there's a fetch (compact) of gale to storm force E'ly in the eastern quadrants of the cyclone aimed into our swell window.

and it's moving v. slowly at present so shouldn't be too duration limited.

Island Bay's picture
Island Bay's picture
Island Bay commented Monday, 30 Dec 2019 at 10:50am

There was definitely some new long-distance energy in the water this morning.
Very inconsistent, but some clean 4ft sets, and light offshores as a special treat.

thermalben's picture
thermalben's picture
thermalben commented Monday, 30 Dec 2019 at 11:53am

Which coast are you at right now IB?

Island Bay's picture
Island Bay's picture
Island Bay commented Monday, 30 Dec 2019 at 12:20pm

Far North NSW, Ben.

mick-free's picture
mick-free's picture
mick-free commented Tuesday, 31 Dec 2019 at 7:29am

Ben, for reference far Northland pulling in 3 foot sets 11secs. Light offshores. Can check Sandy Bay cams. Tomorrow 4 foot.

Mick Free FIFOFOMO