Nias, Mentawai, South Sumatra forecast by Craig Brokensha (issued Tuesday April 22nd)
Best Days: Every day over the coming period
This week and weekend (Apr 22 - 25)
Our recent run of solid swell should be continuing through today with the arrival of a good S/SW groundswell across the region.
This swell is expected to drop through tomorrow and Thursday, with Thursday evening being a low point in swell activity. In saying this, exposed spots aren't likely to drop below 3ft in the Ments.
Into the weekend a moderate increase in S/SW groundswell is due, arriving through Friday, peaking Saturday and easing a touch Sunday.
This is related to a flurry of strong but unconsolidated frontal activity through the Southern Ocean to the south west of WA. Size wise, we should see exposed locations building to 4-5ft later Friday before peaking in the 4-5ft+ range Saturday (slightly smaller around Nias and bigger in South Sumatra). A slow drop is then due Sunday from 4-5ft or so.
Conditions should be favourable most days with a variable airstream in between local thunderstorms and squalls.
Next week onwards (Apr 26 onwards)
Our next pulse of large swell is due to arrive later Tuesday and peak Wednesday next week, generated by a vigorous and long-lived polar low firing up south-east of South Africa Wednesday evening before tracking east towards Australia Thursday and Friday and then breaking down just of WA's South West coast.
Fetch strength will reach the gale to severe-gale range with a period of storm-force winds through Friday (pictured right), setting in motion a large, long-period and inconsistent S/SW groundswell.
Size wise, exposed spots peak Wednesday in the 6ft+ range in the Ments, 6-8ft in Southern Sumatra and 5-6ft at Nias.
We may see a secondary reinforcing pulse for Thursday, but we'll have to confirm this again on Thursday. Winds look to swing a little less favourable and light from the SW through next week, but variable and local land breezes are more than likely each morning.
South Sumatra Forecast