Vietnam Malaysia Singapore Thailand

[Alan Mighty]

Originally Posted by Winfried

The challenge for me is that I do not want to stay from July (boat delivery) to November ( North East Monsum) in Vietnam.

You can delay boat delivery, no? If you delay boat delivery until, say, October and then spend two weeks in sea trials and provisioning, then you'd be good to depart in mid-November.

[Alan Mighty]

Originally Posted by Alan Mighty

Top of the class. As my friend Atoll wrote, late November onwards is almost always safe for a voyage S from Viet Nam. If you watch the NE monsoon develop, you'll find opportunities in mid-November (as in 2005) or even some years in late October.

I hope by now you have started watching the monsoon each day, using the surface streamlines at 10 metres above sea level.

In case you're shy to ask, in the tropics we use surface streamlines instead of a synoptic chart with isobars. That's simply because the atmospheric pressure differences are tiny in the tropics.

Here is today's (7 October 2020) surface streamline chart: wx20201007.jpg

[Alan Mighty]

Originally Posted by Alan Mighty

Here is today's (7 October 2020) surface streamline chart: wx20201007.jpg

Note the two vortices:

* the one at about 14N 125 E, east of the Visayas in The Philippines, has potential to develop into a tropical revolving storm, a typhoon. If it does, it will likely move N.

* the one at about 12N 115E, off the Viet Nam coast between Tuy Hoa and Nha Trang, will likely develop into at least a tropical depression and head W dumping rain across Indochina the into the northern edge of the Gulf of Thailand. That will intensify the SW monsoon winds over Thailand.

English language newspapers in Thailand will keep you up to date with their forecasts, e.g.: https://www.bangkokpost.com/thailand...ve-on-thursday

The Malaysian Meteorological Department gives you forecasts for the major sea areas. See the pull-down menu (labelled "Choose:") to select among Phuket, Northern Straits of Malacca, Southern Straits of Malacca, Samui, Tioman, and so on. https://www.met.gov.my/forecast/marine/waters?lang=en#

The US Navy Fleet Numerical Meteorological and Oceanography Center (FNMOC) is one of the best, if not THE best, sources of surface streamline charts at the moment. FNMOC can deliver pseudo-real time charts or modelled predictions up to 240 hours into the future. Point your browser to: https://www.fnmoc.navy.mil/wxmap_cgi...au=000&set=All for the chart I just posted upthread. Strip out everything starting with "&dtg" to keep the focus on the South China Sea while removing today's date-time-group (DTG) focus.

If you save a surface streamline chart every 7 days, you'll build up a library that will allow you to look at the pattern of change as the SW monsoon diminishes, followed by an intermonsoon, and then the development of the NE monsoon.

The broad brush of that pattern of change, but not the fine details, will happen again in 12 months. So you will soon see the optimum times for your planned voyage.

[Alan Mighty]

Originally Posted by Alan Mighty

* the one at about 14N 125 E, east of the Visayas in The Philippines, has potential to develop into a tropical revolving storm, a typhoon. If it does, it will likely move N.

* the one at about 12N 115E, off the Viet Nam coast between Tuy Hoa and Nha Trang, will likely develop into at least a tropical depression and head W dumping rain across Indochina the into the northern edge of the Gulf of Thailand. That will intensify the SW monsoon winds over Thailand.

If you've been following the surface streamline charts you have found that:

* I was wrong about the vortex east of the Visayas. It moved west, not north.

* the vortex off the Viet Nam coast did do what I predicted. It moved west into the northern Gulf of Thailand.

The result is that if you were in Viet Nam wanting to sail S to the Singapore Strait, if you moved immediately you would only be facing S winds of 10 - 15 knots.

So you would be busy tacking and sail trimming, but you could make it. Winds in the Malacca Strait are light NW, so you'd be facing head winds there today too.

See: https://www.fnmoc.navy.mil/wxmap_cgi...au=000&set=All

[tanngrisnir]

Hi Winfried & Alan,
Been following this with interest. Alan, thanks for the links to the streamline charts.



When I went looking for them earlier in the week I came across this



SE Asia on earth.nullschool.net


Not the same detail but you can go back in time and look at the wind/waves on different dates.

[Alan Mighty]

October - December 2020 will likely be slightly different from October - December 2021, when the OP plans to sail from HCM City to Phuket.

One of the differences is the La Niña phase of ENSO Southern Oscillation, expected to peak in Oct-Nov 2020. That should bring more rain to SE Asia in 2020 and perhaps change the winds a little.

See the reminder from our sisters and brothers in Indonesia: https://en.antaranews.com/news/15871...f-la-nina-bnpb

[Alan Mighty]

Death toll from Tropical Storm Linfa in Viet Nam now up to 17.

https://www.nationthailand.com/edandtech/30395997

https://vietnamnews.vn/society/79333...-flooding.html

[Alan Mighty]

Originally Posted by Alan Mighty

The US Navy Fleet Numerical Meteorological and Oceanography Center (FNMOC) is one of the best, if not THE best, sources of surface streamline charts at the moment. FNMOC can deliver pseudo-real time charts or modelled predictions up to 240 hours into the future. Point your browser to: https://www.fnmoc.navy.mil/wxmap_cgi...au=000&set=All for the chart I just posted upthread. Strip out everything starting with "&dtg" to keep the focus on the South China Sea while removing today's date-time-group (DTG) focus.

The other source of surface streamlines charts is the National Environmental Agency of Singapore. Singapore is one of the richer economies in Southeast Asia and can afford to train meteorologists, use and tap into numeric models, and present information.

NEA Singapore publishes its surface streamline chart daily, valid for 0800 SG time, with forecast charts for +48 hours and +72 hours. See:

Marine Forecasts | Surface Winds |

[Alan Mighty]

Originally Posted by Alan Mighty

NEA Singapore publishes its surface streamline chart daily, valid for 0800 SG time, with forecast charts for +48 hours and +72 hours. See:

Marine Forecasts | Surface Winds |

Attached is the surface streamline chart valid for 0800 14 October 2020 (Singapore time = UTC + 8 hours).

[Alan Mighty]

Originally Posted by Alan Mighty

Attached is the surface streamline chart valid for 0800 14 October 2020 (Singapore time = UTC + 8 hours).

The SG surface streamline chart covers the wider region, in contrast to the US Navy FNMOC surface streamline chart for South China Sea. The latter has a narrow, but highly detailed, focus.

Why go to the trouble of mentioning these two sources of surface streamlines, especially given that the OP shows no sign of active participation?

The simple answers are:

1. when planning a voyage, such as one from HCM City, Viet Nam, to Phuket, Thailand, you need to be focused on both the narrow and the wide view;

2. the standard advice, from my friend Atoll and myself, is that late November is a reliable time for such a voyage. The OP is locked into a time schedule that has contradictions to that. I've done my best to emphasise that checking the surface streamlines daily or weekly is essential.

The substance behind those two assertions may be shown in 7-8 days. If the forward numeric models are to believed, 21-22-23 October may well show conditions that would be just peachy for a big cat to sail from HCM City direct to the Singapore Straits and around into the Malacca Strait.

[Alan Mighty]

Originally Posted by Alan Mighty

If the forward numeric models are to believed, 21-22-23 October may well show conditions that would be just peachy for a big cat to sail from HCM City direct to the Singapore Straits and around into the Malacca Strait.

Almost on schedule ... light beam reaching conditions from HCM City, Viet Nam, to the Singapore Strait.

[Alan Mighty]

Originally Posted by Alan Mighty

Almost on schedule ... light beam reaching conditions from HCM City, Viet Nam, to the Singapore Strait.

The unfortunate catch is that other things (a tropical revolving storm) are developing fast, so these conditions look like only lasting 48 hours.

But that's the deal: a stable NE monsoon will develop in mid- to late-November. Until then, in the intermonsoon season, the situation is dynamic.

But if, as with the OP, you have to sail to a schedule, then you need to be alert to opportunities, judge how large the window of opportunity is, and choose (or not) to take the opportunity.

[Alan Mighty]

The series of Tropical Revolving Storms that are forming E of The Philippines and then travelling W and making landfall in Viet Nam are causing several problems.

One problem is of course the effects on Viet Nam, with heavy rain leading to fatal landslides, for example, and on The Philippines. See: https://newsinfo.inquirer.net/135003...s-its-strength

There's another less obvious consequence: because the TRSs are travelling W instead of North, Taiwan is in drought. See: https://taipeitimes.com/News/editori.../20/2003745453

[Pelagic]

And we have another one in this family of TRS' crossing the same track as the one tonight. The seemed to be spaced a week apart as this next one will hit Philippines Nov 1

[tanngrisnir]

Even if the OP is not following this weather pattern I have been. I figured if I keep looking at it regularly I may understand Alan's ability to see what is coming. His prediction up thread was pretty spot on.

It looks like there is a significant wind direction reversal as a big depression approaches the Philippines that lasts a couple of days then as the devastation moves on-land in Vietnam the conditions return to how they were.

Two days ago, wind was on the nose to Singapore and now they are favourable again for the next 3 days or so.

South China Sea loop