November 13, 2023
We have a friend who is planning to leave tomorrow to sail to the Philippines. Thers’s an alarming tropical depression shown on tropicaltidbits.com/storminfo today called 17W that might intercept his planned route.
I would normally do a routing on PredictWind to look at this passage. Today, instead, I had the idea to ask ChatGPT. Here’s the conversation:
Your planned sailing passage from Lembeh Island, North Sulawesi to Davao City, Philippines, departing tomorrow at 6 am, could be affected by the current weather conditions and the progression of Tropical Depression 17W.
Tropical Depression 17W:
- As of the latest updates, Tropical Depression 17W is located 267 km south of Yap and is moving west-southwestward at a speed of 17 km/h (9 knots).
- Over the next 24 to 36 hours, 17W is forecasted to track slowly westward, and after 2 days, it will accelerate to the west-northwest. In the following 3 days, it is expected to continue this west-northwest track before shifting northwestward over the next 5 days.
- The intensity of 17W will likely struggle to develop in the next 2 days due to disorganized structure and moderate to high easterly shear. However, it’s expected to gradually intensify after 2 days, reaching a peak intensity of 85 km/h (45 knots) in 4 days.
- The maximum significant wave height associated with 17W is around 4 meters (13 feet).
Weather Forecast for Lembeh Island:
- The current weather on Lembeh Island includes scattered clouds, with a temperature of 91 °F and winds from the north at 5 mph.
- The forecast for November 13 includes isolated thunderstorms late in the day, mostly cloudy conditions, with a temperature of 90 / 73 °F, and winds at 4 mph.
- On November 14, the weather is expected to be cloudy with passing showers, a temperature of 89 / 75 °F, and similar wind conditions.
Marine Forecast for the Region:
- The general marine forecast indicates light to moderate northeasterly flow in the northern part of Indonesia, with easterly to southerly gentle to moderate flow in the southern part.
- Moderate sea conditions are expected in various regions, including the Pacific Ocean north of Halmahera to Papua.
- Swell heights of 1.25 to 2.5 meters are expected in some areas, with 2.5 to 4.0 meters swell in the Indian Ocean southern of Central Java to East Java.
Considering these conditions, your journey may encounter moderate seas and the potential for increased wind speeds and swells, especially if the path of your sail intersects with the forecasted track of Tropical Depression 17W. It is advisable to continuously monitor weather updates and maritime advisories for any changes in the forecast that could impact your sailing conditions.
This is so much better than I expected. It’s actually a rather thoughtful answer. To come up with it, ChatGPT checked the following online:
- Tropical Depression 17W on Zoom.earth/storms – This isn’t something I’d have looked at, but I’ve got to say, the information is really pretty good.
- Weather in Pulau Lembeh, Indonesia at timeanddate.com – OK, not a source I would use.
- Pulau Lembeh 14 Day Extended Forecast again at timeanddate.com.
- Indonesian Weather Bulletin For Shipping at Pusat Meteorologi Maritim – Something I’ve never heard of.
Here’s what the tropical depression looks like on zoom.earth:
To provide a comprehensive overview, here are key points from the weather routing analysis using Predict Wind:
I’ll restate what PW says below that table: At 0.2+ g’s Vertical Acceleration, it is dangerous to perform tasks and potential seasickness. It gets up to over 0.3 g’s here.
Again, PW says: 50% Slamming incidence or greater may lead to hull damage or crew injuries. Here, we see it get up to 70%. Yikes!
With this forecast and the added real possibility of crossing paths with a full-blown cyclone, the Legacy crew would do anything necessary to avoid this passage.
As a final note:
I’m impressed with Chat’s answer to my query, though for us, it’s not going to replace Bob McDavitt anytime soon!
-Rich
