Japan Wind Gust & Wave Monitor

Navigation

• Wind / Wave tabs — Switch between wind gust and wave height layers on the map.
• Lead Time — Select how far ahead to forecast: +10m to +120m for wind, +1h to +6h for waves.
• Metric — Choose what value to display as station colours (see definitions below).
• Click any station — Opens a popup with the full probabilistic forecast and 6-hour observation history.
• Scroll / pinch to zoom — Zoom in on any port or coastal area for detail.

Wind Gust Metrics

Metric	Definition	Operational use
Gust p50	Median ML forecast gust speed (m/s). 50% chance the actual gust will be below this value.	Best estimate for planning — use for normal scheduling decisions.
Gust p90	90th percentile ML forecast (m/s). Only 10% chance the gust will exceed this value.	Conservative estimate — use for safety-critical decisions such as crane operations or cargo handling.
P > 10 m/s	ML-derived probability (0–100%) that the gust will exceed 10 m/s (Beaufort 5 — Fresh Breeze).	Threshold for cautious outdoor operations. Light crane work becomes difficult.
P > 15 m/s	Probability that the gust will exceed 15 m/s (Beaufort 7 — Near Gale).	Standard threshold for suspending crane and exposed cargo operations at most ports.
P > 20 m/s	Probability that the gust will exceed 20 m/s (Beaufort 8 — Gale).	All exposed deck and terminal operations should be suspended. Vessel manoeuvring risk increases.

Wave Metrics

Metric	Definition	Operational use
Hs p50 (m)	Median ML forecast of significant wave height (Hs) in metres. Hs is the average of the highest one-third of waves — the value a trained observer would estimate visually.	Best estimate of sea state for vessel approach and berthing decisions.
Risk Level	Composite risk score (Low / Moderate / High / Extreme) derived from the ML forecast — combining wave height, wave period, and forecast uncertainty.	Quick at-a-glance indicator for port operations centres.
P > 1.5 m	ML-derived probability that Hs will exceed 1.5 metres.	Caution threshold for small vessel operations and exposed anchorages.
P > 2.5 m	ML-derived probability that Hs will exceed 2.5 metres.	Operational limit for many vessel types. Port entry and cargo transfers should be reviewed.

AIS Vessel Layer

Live vessel positions are sourced from the Datalastic AIS network, covering Japan and the surrounding seas (Japan Sea, Pacific, Tsugaru Strait, Korea Strait, and Okinawa/Ryukyu approaches). Data refreshes every 5 minutes.

Vessels are shown as small directional arrows — the arrowhead points in the vessel's course-over-ground direction. Click any vessel to see its name, type, flag, speed, course, draft, destination, and position age.

Note: Vessel colours are intentionally chosen to be distinct from the wind and wave magnitude colour scales (which use pale blue → green → yellow → orange → red → purple) to avoid ambiguity on the map.

Colour	Vessel type
	Tanker — oil, chemical, and other liquid bulk tankers
	LNG / Gas Carrier — liquefied natural gas and gas carriers
	Container / Cargo — container ships and general cargo vessels
	Bulk Carrier — dry bulk vessels (grain, ore, coal)
	Passenger / Ferry — cruise ships and domestic ferries
	Vehicle / RoRo — car carriers and roll-on/roll-off vessels
	Fishing — commercial fishing vessels
	Tug / Work Vessel — harbour tugs, pilot boats, service craft
	Other / Unknown — vessels not classified above

Data Sources & Refresh

• Wind observations: JMA AMeDAS network — 1,286 stations nationwide, updated every 10 minutes.
• Wind forecast: Fathom Science proprietary ML model, runs within ~20 minutes of each observation cycle, producing probabilistic forecasts to +120 minutes.
• Wave observations: NOWPHAS coastal wave gauge network — 52 stations, updated every 20 minutes.
• Wave forecast: Fathom Science proprietary ML model, produces probabilistic forecasts to +6 hours after each update cycle.
• AIS vessels: Datalastic AIS network — live vessel positions covering Japan and Japan Seas, refreshed every 5 minutes.
• Port markers: Key operational ports across Japan (container, car carrier, bulk, LNG terminals).

Data reflects the last JMA/NOWPHAS observation cycle. ML forecasts are probabilistic — actual conditions may differ. Always consult official JMA warnings for safety-critical decisions.