Another Week Of Gold Ahead: Bali, Indonesia Surf Forecast 15 - 22 September 2015
Forecast Issued Tuesday, 15 September, 2015 by Matthew McKay
Yet another pulse of SSW groundswell is on the cards for early next week.
*Stay tuned to the Coastalwatch Wave Tracker to keep your finger on the pulse
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The late season flourish of waves is set to continue across the region. The large SSW that is currently propagating toward the southern coast of Indonesia is set to ease during the coming week. Fun waves ranging between 3 and 6 feet should be on offer over the next few days before Saturday marks a low point in wave energy.
Throughout the past month, the Southern Ocean storm track has been operating like clockwork; effectively delivering a new, large round of swell at the beginning of each week. Fortunately for surfers, this cycle is set to continue as yet another solid SSW/SW is forecast to grace our shores by Monday, September 21.
Wednesday September 16
Easing SSW swell. 4-6ft at exposed breaks decreasing to 4-5ft throughout the day. Grading smaller elsewhere. WIND: ESE 5-10 knots increasing to 10-15 knots.
Thursday September 17
Short period SSW swell. 3-4ft at exposed breaks. Grading smaller elsewhere. WIND: ESE 5-10 knots increasing to 10-15 knots.
Friday September 18
Short period SSW swell. 3-4ft at exposed breaks. Grading smaller elsewhere. WIND: SE 10-15 knots.
Saturday September 19
Small short period SSW swell. 2-3ft at exposed breaks. Grading smaller elsewhere. WIND: SE 5-10 knots tending SSE 5-10 knots.
Sunday September 20
New long period SW groundswell mixed with old short period SSW swell. 2-3ft+ with larger inconsistent sets at exposed breaks. Grading smaller elsewhere. WIND: SE 5-10 knots tending SSE 5-10 knots.
Monday September 21
Building long period SW groundswell. Initially 4-5ft with larger sets, increasing to 6-8ft at exposed breaks. Grading smaller elsewhere. WIND: SSE 5-10 knots tending SE 10-15 knots.
Tuesday September 22
Solid SSW groundswell. 8-10ft easing to 6-8ft by the afternoon at exposed breaks. Grading smaller elsewhere. WIND: SE 5-10 knots increasing 10-15 knots
Indonesia’s late season has not disappointed. Over the past three weeks, the Southern Ocean storm track has delivered a series of powerful SSW/SW groundswells to the region. The most recent swell was generated by a deep polar low in the Southern Indian Ocean. Wind speeds in the 45-50 knot range produced open ocean wave heights of 35ft+ within the core of this system; consequently resulting in a solid SSW groundswell reaching the shores of Indonesia by early Monday morning.
Solid 8ft+ waves are still evident across the more exposed breaks as of Tuesday morning before an expected decline in energy throughout the day. Wave heights are forecast to decrease further overnight as this storm migrates out of our swell window. From Thursday, we should see a renewal in short range SSW swell which will see wave heights of 2-4ft maintained until Sunday morning. Beyond this, yet another pulse in long range SSW groundswell is due on Sunday afternoon; wave energy will build throughout Monday with a peak expected during the early hours of Tuesday September 22.
A decrease in wave energy is expected over the coming days as the strong, swell producing storm weakens and migrates north east toward the West Australian coast. A fairly narrow band of winds in the 25 to 30 knot range will generate a mid to short period SSW swell across the Indonesian coast. From this we will see a sustained run of fun wave heights over the coming day before another polar low makes its presence felt by early next week. As mentioned in last week’s forecast, an active long wave trough is effectively guiding these storms into our swell window. The subtropical band of high pressure located north of these systems is setting up strong pressure gradients, directing a broad fetch of SW gales toward the Indonesian Archipelago.
At this stage, current GFS model guidance is showing the eastward migration and subsequent consolidation of a strong polar storm. This storm is expected to peak on Thursday with a core low pressure of 960hPa. The interaction of this storm with the high pressure system located within the Central Indian Ocean will produce SSW winds in excess of 50 knots on the north-west flank of this system.
If this model guidance proves true, these storm force winds, located NE of Heard Island (50S,90E) will generate large seas with open ocean wave heights in excess of 40ft (see WaveTracker image). The distance between swell source and Indonesia will mean that we won’t see any signs of this swell until Sunday afternoon; where the leading forerunners will act as a pre cursor to the impending swell. The swell should build steadily through Monday, speculatively reaching 6-8ft by dark before a peak in the 8-10ft range on Tuesday morning
Beyond Tuesday, we will see solid waves in the 6 to 8 foot range persist overnight into Wednesday. By Thursday September 24, wave energy will decrease steadily decline throughout the day as this storm weakens. Looking further ahead, long range model guidance is hinting at a large band of high pressure making its way into the Indian Ocean. The location and size of this high may be the first indictor that our epic late season run of waves will soon come to an end. All is not lost though.
The latest WaveWatch III data shows another possible rise in SW groundswell due in approximately two weeks’ time. It is important to note that due to the long range nature of this forecast there is obvious divergence amongst global weather and wave models so please check back next week for an update. In the meantime, make the most of the next 10 days.
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