Forecast swell for NSW 4th/5th/6th

Posted by: Alex Zadnik

Forecast swell for NSW 4th/5th/6th - 01/08/2002 11:25

Thought I would follow on from Thermal Ben's Southern Ocean forecast with one of my own.
Computer models are in general agreement of a cut-off cold pool moving over southern NSW on Saturday. After helping to produce Alpine snow falls on the weekend, this cold pool will generate a surface low off the NSW south coast on Sunday. Swell will build along the NSW south and central coasts late Sunday, early Monday, although strong southerly winds will probably not make for favourable surfing conditions. Tuesday morning looks like being the time for some excellent surf. Swell should be in the 5-7ft range and early morning drainage winds (westerly) will keep conditions clean. Swell could possibly be larger, as GASP progs a strong pressure gradient between the Tasman low and a high over the South Island of New Zealand (the fetch of the winds also looks promising). We shall wait and see, but it all looks promising for Tuesday next week.
Alex
Posted by: thermalben

Re: Forecast swell for NSW 4th/5th/6th - 01/08/2002 15:05

Hey Alex

So is this an official TWC forecast? wink

I've just had a quick scan and to be honest I'm not quite as confident for excellent Sydney surf (although I'm unsure as to whether you're classifying this a 'general' swell forecast, or a 'significant swell event').

Although all models are pointing towards a surface low, it seems to me like they don't agree on where it will form and how strong. MRF does have a small area of southerly winds on Sunday night likely to whip up something, but I have a feeling it'll quite possibly be locally generated and will diminish rather quickly. It does hint at forming a SE fetch from Tuesday onwards in the eastern Tasman, but I imagine the effects from this won't be properly felt until later Wed or Thurs.

Interestingly, NOGAPS is progging a slightly deeper low, however the swell models don't display much from it yet - perhaps a result of coarse model resolution. GASP and ECMWF don't have the pressure gradient strong enough or sustained enough for significant swell development IMO (although the external ECMWF is a little, erm, 'broad' for these purposes).

So at this stage I'd be more inclined to favour bumpy increasing southerly swell around 3-4ft for Monday - southern extremities of Sydney beaches likely to dip out due to the short period - with nice conditions early Tuesday but on a dropping windswell and marginally increasing E groundswell around 2-4ft. After that I reckon it'll pick up slowly but steadily from Wed thru' Fri, however Sydney looks like benefiting the most from swell direction during Thurs - Sat. If MRF pulls off the prolonged ESE flow through the latter part of the week, surf size could be up around 6-8' for later Thurs, Fri and Sat.

I'll keep an eye on this one, it looks like it might have a few surprises in store!
Posted by: Alex Zadnik

Re: Forecast swell for NSW 4th/5th/6th - 01/08/2002 15:41

Hey Ben,
No this is not the "official TWC forecast"! It is a bit of a speculative/optomistic forecast for next week. I would say it is a general surf forecast, rather than proging a significant swell event(I am not saying it will be a huge swell, but definitely more substantial than anything in the past two or three weeks). We are a bit surfed deprived up here(it has not been above about 4ft), so I am probably forecasting best possible outcome!
Although that being said, I haven't been too far wrong on my Sydney forecast of late.
Onto the forecast......... I do agree that the duration of a strong pressure gradient looks as though it may be a limiting factor (apart from the MRF model (which is now actually AVN)). I actually agree with most of what you said! I do however think that the E ground swell will be fully developed by Tuesday and die out during Wednesday (unless MRF comes off). I'll stick by my forecast of 5-7ft (although probably ambitious, 3-4 ft on your part might be a good call). We'll wait and see anyway, here's hoping it's good!
Thanks for the reply, I'll keep you updated on how it all goes.....
Cheers,
Alex
Posted by: thermalben

Re: Forecast swell for NSW 4th/5th/6th - 01/08/2002 23:41

Hmmm...one model run and GASP already looks like it's fallen off the rail! Doesn't seem to like the prospects of that low developing at all frown

However MRF is still keeping it alive (albeit slightly!), but I've altered my view from the earlier post above. You might be right on the size factor for Tuesday - although I am still a little doubtful on its quality as the swell is being generated so close to the continent.

The SE belt of wind I also mentioned before is now progged to be a little further north in lattitude than earlier model runs, and a little later in development too. This could have dire consequences for actual surf size in Sydney as it will aim the main swell window further north too (however QLD'ers will be happy....especially with that sand buildup at Snapper...)

Gee, you picked a dynamic one to delve into Alex! Nice work smile
Posted by: thermalben

Re: Forecast swell for NSW 4th/5th/6th - 02/08/2002 15:33

how's the Thurs 1/8 18Z GASP run for 12Z Wed next week? eek

However on a more realistic note MRF/AVN is still quite happy to keep a steady SE flow for a couple of days; looks like QLD will benefit quite well late next week from this.
Posted by: Alex Zadnik

Re: Forecast swell for NSW 4th/5th/6th - 02/08/2002 18:59

I'd love to be at Hotham on Thursday if GASP comes off! Fresh un-traked powder.......mmmmmmmmm
On the swell front it's still looking promising for early next week on the NSW coast, I'm off for the weekend now, but I'll post Monday/Tuesday with an update on how things unfold.
Have a good weekend,
Alex
Posted by: thermalben

Re: Forecast swell for NSW 4th/5th/6th - 04/08/2002 12:07

Now we're a little closer to this event the high-res models are defining the shape of the low a little more, and it looks like a mixed bag for Syd surf prospects to me.

The surface low is undergoing cyclogenesis as we speak, and AVN is progging a thin band of SSW winds to whip up parallel to the coast around 40kts or so later today. This will produce short period surf for the Sydney area, but as the underlying swell direction is pretty unfavourable for this coastline (and the winds location is so close to the mainland), I can't see anything of substance for Monday or Tuesday. I think you're probably right with the surf size Alex (5-6ft or so for later Mon/Tues on south facing beaches), but as the wind drops I imagine the swell will follow suit.

However what's of interest to me is the eastern side of the low which looks like developing a nice ESE fetch during Monday - this could provide some strength and a small increase in the groundswell department for later Tuesday and Wednesday for Sydney surfers. And with light winds generally offshore there should be some clean surf around 4-5ft, although a local increase in wind speed from the SW Tues arvo will diminish the windswell component a tad further. The swell will then abate gradually through the rest of the week.

This set up is looking very nice for QLD though; they'll receive a small solid burst of S groundswell from this system later Monday, then a steady groundswell around 4-6ft from the ESE through until the end of the week. As if they need any more perfect surf!! laugh
Posted by: pingtang

Re: Forecast swell for NSW 4th/5th/6th - 04/08/2002 16:32

I went down to Bawley point(near Batemans Bay) very early today.There was about 1-1.5 metres of swell,down there on open beaches facing southwards.The wind was a westerly early on,so there were some great waves around for a couple of hours.There was plently of swell out to sea(2-3metres),but most of it appeared to be going past.The lines looked good,but were fairly close together.

Later on in the morning,the wind swung to the SE,and intensified rater rapidly,to about 20-25knots.This made conditions really choppy,and pretty much disguised what swell there was.

Swell is heading towards Sydney,but the wind will be unfavourable.
Posted by: thermalben

Re: Forecast swell for NSW 4th/5th/6th - 05/08/2002 10:09

Thanks for the report Pintang.
Your examples are typical of locally generated wind swell, and with "..plently of swell out to sea..most of it appeared to be going past.." I can't see much of it refracting into bays and points at this point in time (the locations that are currently sheltered from these winds at the moment).
Needs another day or two to get properly sorted.
Posted by: thermalben

Re: Forecast swell for NSW 4th/5th/6th - 05/08/2002 10:26

Actually I thought I'd just cut n' paste a few comments from RealSurf regarding today's conditions, and see how they correlate with what we have been discussing...

"2-4 feet and likely bigger at spots open to the south swell" (Manly)
"chest to shoulder high waves on the Point and reasonably nice looking conditions" (Dee Why)
"Swell is on the rise again, though a tad short on power, there's 3-4 ft of swell" (Narrabeen)
"2-4ft, and lumpy...relatively short rides" (Bondi)
"Looks like quite a bit of South in the swell. Bronte around waist to overhead...the point was looking a little tame and weak. Tama has way more energy" (Tama/Bronte)
"Messy and bumpy 2ft Southerly swell" (Coogee)
"Dead Flat" (QLD)

The Tama report in particular shows the effects of swell direction along different aspects of the beaches.
Posted by: Alex Zadnik

Re: Forecast swell for NSW 4th/5th/6th - 05/08/2002 12:51

Hey Ben,
Yesterday afternoon had about 1-2ft of southerly wind swell at the northend of Maroubra (more exposed to south swells). Wind was strong SSW making for pretty ugly conditions. I haven't had a chance to look today, so the real surf report is the best I can do. I should mention I will predominately be using Maroubra as the beach for observations.
I'll have a look at the charts after lunch, but it looks like nothing huge is to be expected. Probably around 4ft tomorrow and swell dropping out during Wednesday. Still might be some nice waves around early tomorrow though.
Posted by: thermalben

Re: Forecast swell for NSW 4th/5th/6th - 05/08/2002 13:02

Hey Alex
There's a few updated reports of slowly increasing surf size (DeeWhy) on Realsurf... however the onshore wind change probably won't do many favours this afternoon.

That possible 'ESE fetch' mentioned above looks like it's just starting to develop (via sat. derived winds), so we'll need to keep a close eye on it as to the strength and whether the surf size builds Tues/Wed as a consequence.

QLD'ers will awake to a slightly different ocean tomorrow morning methinks smile
Posted by: thermalben

Re: Forecast swell for NSW 4th/5th/6th - 06/08/2002 19:52

Surf size has dropped back again today (should have stuck with my original forecast comments!), with general size around the 2ft mark. QLD has picked up, with surf going from flat yesterday to 2-3ft today, however it remains to be seen if the ESE fetch that was expected to develop today generates anything substantial for northern NSW and QLD. Satellite derived winds don't offer much hope; it looks like a short lived event and unfavourable in direction for anything noteworthy.

Will have to wait until tomorrow smile
Posted by: thermalben

Re: Forecast swell for NSW 4th/5th/6th - 07/08/2002 10:00

Grrrrrrr...
flat in Sydney, 1-2ft in Qld.

Meanwhile, it's pumping in SA and Vic again laugh
Posted by: Thunderstruck

Re: Forecast swell for NSW 4th/5th/6th - 07/08/2002 14:27

Hows it going Ben? I havent been out for a while now..but whats the best spot ATM? South Coast should be ok...the mid alright....that next low coming thru should soon so perhaps that could throw up some sort of action for the South Coast..it really depends on whether its going to form west of east of us or at all...

TS cool
Posted by: pingtang

Re: Forecast swell for NSW 4th/5th/6th - 07/08/2002 21:33

Its FLAT and its not looking too good for the next 4 days in my opinion.This high pressure system will dominate our weather,and any wave action on our beaches.

The next hope for surf,might be next Monday or Tuesday,when the high moves towards New Zeland.
Posted by: Alex Zadnik

Re: Forecast swell for NSW 4th/5th/6th - 08/08/2002 09:49

G'day,
The prediction really didn't come off this time, Tuesday morning was around 3ft at Maroubra, 4ft on the biggest sets (very infrequent). By all reports the swell completely died out on Wednesday.
The low weakened pretty rapidly and yesterdays' strong westerlies didn't help the situation.
The wait for REAL SWELL continues on the east coast..........
Alex
Posted by: temp trace

Re: Forecast swell for NSW 4th/5th/6th - 08/08/2002 11:05

Morning all,
Some epic surf up here Tuesday. Solid 3/4 foot with (very) occasional 5 footer in the am a little smaller by late arvo. Direction was ESE in the morning and ENE? by arvo. Back down to under 2 foot by Wednesday morning. Today around the 3 foot mark but the cross shore's not doing much for it.
Posted by: thermalben

Re: Forecast swell for NSW 4th/5th/6th - 08/08/2002 19:40

Thanks TT for that report. It's hard to get good verification outside of the metro areas.

Interestingly the swell's come up from yesterday's flatness in the Sydney area, perhaps a result of the mild ESE flow originally forecast for late Tues/Wed in the Tasman (except of weaker strength and duration than initially thought).

Realsurf reported today as such:
DeeWhy - building swell to chest high (afternoon)
Manly - 2' (morning)
Curly - peaking at head high (morning)
Maroubra - 2-3' (afternoon)
Gold Coast - 2' (morning)

There's not much consistency with the reports though, and could be quite localised. I'm watching with interest as to whether it hangs around for tomorrow.
Posted by: pingtang

Re: Forecast swell for NSW 4th/5th/6th - 08/08/2002 20:51

Im a little suprised in the swell increase as well.It was probrably the result of the easing westerlys.Some swell was always out to sea,and it has been allowed to come in with the lighter winds.It was probrably a metre down here.

Tomorrows forcast is 2-2.5metres out to sea.Im predicting about 1 metre sets on the more open beaches.There should be some swell around anyway. smile
Posted by: temp trace

Re: Forecast swell for NSW 4th/5th/6th - 08/08/2002 20:56

Quote:
Originally posted by thermalben:
I'm watching with interest as to whether it hangs around for tomorrow.
Your not the only one smile

Latest coastal waters is going for 2/2.5m but a check this arvo and the swell has dropped a good foot since this morning.

Direction is the biggest problem (for the coast anyway) a few ship reports came in during the day with 3/3.5m of south swell 100km or so off the coast. A quick check of quickscat and you can see why.

As pingtang has already said I don't hold to much hope for the weekend so Friday could be the go fingers crossed anyway.
Posted by: pingtang

Re: Forecast swell for NSW 4th/5th/6th - 08/08/2002 21:07

A moderate E/NE wind is predicted on Friday afternoon.This will hack into the swell,and reduce the prospects of a wave on Saturday.
Posted by: thermalben

Re: Forecast swell for NSW 4th/5th/6th - 09/08/2002 10:02

Hmmmm...interesting! I can only vouch for the online reports, but I am reading that it's picked up again...

Reports are as such:
DeeWhy - head high sets
Manly - 1-3'
Bondi - 3'+
Bronte - chest high (Tama bigger)
QLD - 2' (but better and more consistent)
Posted by: temp trace

Re: Forecast swell for NSW 4th/5th/6th - 09/08/2002 11:23

Your right there Ben - what a difference a night makes! A good 4/5 foot with even bigger sets this morning the quality isn't much chop the banks just aren't handling the size.

Just went past on my way home awhile ago it appears that its dropped a little from earlier. So Saturday morning mightn't be put of the question just yet smile WW3 is dropping the swell slowly during the day and the meso wam is trying to hold 2m over my area at least during the day but having a look at the laps sswinds can't see how the swell can do anything but drop rapidly during the day?
Posted by: thermalben

Re: Forecast swell for NSW 4th/5th/6th - 09/08/2002 11:43

Wow! That's veeery interesting TT.

I've been too busy to follow this system since last weekend, but after a quick scan through the CIMSS and Quickscat winds, perhaps it's just a huge refraction from the current synoptic event - the wind has been roaring through the Tasman over the last few days (how big would some of the South Pacific Islands be out of this system? 12'? 15'? eek )

I know the wind direction is SW thru S, but at 50kts there's an awfully large swell generation happening and 4ft surf isn't that much to expect along the East Coast.....or is it? The buoy are reporting swell directions from the SSE...this is an interesting case example indeed.

Just a pity that I don't archive wind images from the east coast...only the western sector... frown

As for tomorrow; at this stage I'd be expecting more of the same as per today. No huge increase on today size, but no overnight drop to flatness either (how's that for fence sitting? laugh ).
Posted by: temp trace

Re: Forecast swell for NSW 4th/5th/6th - 09/08/2002 12:35

Ben just had a look at oceanweather is that 5m at 9 sec?
Posted by: thermalben

Re: Forecast swell for NSW 4th/5th/6th - 09/08/2002 12:54

yep eek ... the same area (could be the same ship?) is reporting SW winds of 35kts. Pity this site doesn't always report swell size...and how much of this is groundswell or localised windswell is left for interpretation. Still, nice to have some regular verification smile

*sorry... map URL changes every hour* had to alter post...
Posted by: Alex Zadnik

Re: Forecast swell for NSW 4th/5th/6th - 09/08/2002 13:05

Hey Ben,
I think your spot on with that huge refraction call. It has suprised me a few time along the east coast that we have recieved swell from what appears to be a straight SW fetch in the southern Tasman Sea/Southern Ocean.
I don't see it sticking round for long though. If there is still swell tomorrow I'll be pretty suprised (but happy!).
Alex
Posted by: pingtang

Re: Forecast swell for NSW 4th/5th/6th - 09/08/2002 21:54

I wont be suprised if theres some swell lingering around tomorrow morning.When I went past Gerringong this evening,there were some sets that were over head-high.I am expecting a decrease in size,but there should be something there.
The Illawarra coastal waters forcast,is suggesting a 2-2.5 metre swell,decreasing to 1.5-2metres in the morning.The Sydney forcast mentions no decrease.With W-NW winds predicted,there should be some nice waves.It should be small though-say 1 metre or less.
Posted by: pingtang

Re: Forecast swell for NSW 4th/5th/6th - 10/08/2002 13:40

Morning report-

Swell is still lingering around,but it has dropped substantially overnight.Its about 1metre on the sets,and its dropping off pretty quickly.There was a light northerly down here,early in the morning,so open beaches were side-shore.So OK waves,were in the protected northern corners.

I had an alright surf earlier today,but it was small.Tomorrow should be about 1FT on open beaches.