Question 1

What weather and ocean models are available in NavimetriX?

Henri · Accepted Answer

NavimetriX provides access to over 70 weather, wave, and current models from leading meteorological agencies worldwide.

🌍 Atmospheric Models — Global

GFS — NOAA — 28 to 222 km — 16 days

ECMWF IFS — ECMWF — 28 to 111 km — 15 days

ECMWF AIFS — ECMWF — 28 to 111 km — 15 days

ICON Global — DWD — 14 to 111 km — 5 days

Arpège Monde — Météo-France — 28 km — 4 days

GDPS (GEM) — CMC Canada — 17 km — 10 days

🇪🇺 Atmospheric Models — Europe

Arpège Europe — Météo-France — 11 km — 4 days

Arome — Météo-France — 3 km — 42 hrs

Arome HD — Météo-France — 1 km — 36 hrs

ICON Europe — DWD — 8 km — 5 days

ICON D2 — DWD — 2 km — 48 hrs

UKV — Met Office — 6 km — 5 days

🌎 Atmospheric Models — Americas

NAM — NOAA — 11 km — 84 hrs

HRRR CONUS — NOAA — 3 km — 18 hrs

Arome Antilles — Météo-France — 3 km — 48 hrs

Arome Guyane — Météo-France — 3 km — 33 hrs

🌏 Atmospheric Models — Pacific & Indian Ocean

Arome Polynésie — Météo-France — 3 km — 48 hrs

Arome Calédonie — Météo-France — 3 km — 48 hrs

Arome Réunion-Mayotte — Météo-France — 3 km — 48 hrs

🌊 Wave Models (Sea State)

GFS Wave — NOAA — Global — 28 to 111 km — 16 days

MFWAM Global — Météo-France — Global — 11 to 56 km — 4 days

MFWAM France — Météo-France — France — 3 km — 4 days

IFREMER WW3 — Ifremer — France coasts (14 zones) — 190m to 500m — 4 days

🔵 Oceanic Current Models — Global

Copernicus Global — Copernicus — 9 km — 5 days — oceanic currents only (Gulf Stream, etc.)

🔵 Oceanic and tidal Current Models — Global

Copernicus Global SMOC — Copernicus — 9 to 56 km — 5 days

🔵 Oceanic and tidal Current Models — Europe

Copernicus IBI — Iberian-Biscay-Ireland — 3 km — 5 days

Copernicus ENWS — NW Shelf / North Sea — 2 km — 5 days

Copernicus BALTIC — Baltic Sea — 4 km — 5 days

Copernicus MED — Mediterranean — 5 km — 5 days

SHOM Manche-Gascogne — Channel & Biscay — 2 km — 5 days

SHOM Méditerranée Nord — NW Mediterranean — 2 km — 5 days

IFREMER — France coasts (10 zones) — 250m to 3 km — 4 days

🔵 Oceanic and tidal Current Models — Americas

MSC Saint Laurent — St. Lawrence / Atlantic Canada — 1 km — 84 hrs

NCOM Alaska - N. Calif — Alaska to N. California — 4 km — 90 hrs

NCOM Caribbean — Gulf of Mexico & Caribbean — 3 km — 90 hrs

NCOM Hawaii — Hawaii — 4 km — 90 hrs

NCOM South California — Southern California — 4 km — 90 hrs

NCOM US East Coast — US East Coast — 4 km — 90 hrs

Read also: Why are there global models and regional models

Question 2

What weather and ocean models are available in NavimetriX?

Henri · Accepted Answer

NavimetriX provides access to over 70 weather, wave, and current models from leading meteorological agencies worldwide.

🌍 Atmospheric Models — Global

GFS — NOAA — 28 to 222 km — 16 days

ECMWF IFS — ECMWF — 28 to 111 km — 15 days

ECMWF AIFS — ECMWF — 28 to 111 km — 15 days

ICON Global — DWD — 14 to 111 km — 5 days

Arpège Monde — Météo-France — 28 km — 4 days

GDPS (GEM) — CMC Canada — 17 km — 10 days

🇪🇺 Atmospheric Models — Europe

Arpège Europe — Météo-France — 11 km — 4 days

Arome — Météo-France — 3 km — 42 hrs

Arome HD — Météo-France — 1 km — 36 hrs

ICON Europe — DWD — 8 km — 5 days

ICON D2 — DWD — 2 km — 48 hrs

UKV — Met Office — 6 km — 5 days

🌎 Atmospheric Models — Americas

NAM — NOAA — 11 km — 84 hrs

HRRR CONUS — NOAA — 3 km — 18 hrs

Arome Antilles — Météo-France — 3 km — 48 hrs

Arome Guyane — Météo-France — 3 km — 33 hrs

🌏 Atmospheric Models — Pacific & Indian Ocean

Arome Polynésie — Météo-France — 3 km — 48 hrs

Arome Calédonie — Météo-France — 3 km — 48 hrs

Arome Réunion-Mayotte — Météo-France — 3 km — 48 hrs

🌊 Wave Models (Sea State)

GFS Wave — NOAA — Global — 28 to 111 km — 16 days

MFWAM Global — Météo-France — Global — 11 to 56 km — 4 days

MFWAM France — Météo-France — France — 3 km — 4 days

IFREMER WW3 — Ifremer — France coasts (14 zones) — 190m to 500m — 4 days

🔵 Oceanic Current Models — Global

Copernicus Global — Copernicus — 9 km — 5 days — oceanic currents only (Gulf Stream, etc.)

🔵 Oceanic and tidal Current Models — Global

Copernicus Global SMOC — Copernicus — 9 to 56 km — 5 days

🔵 Oceanic and tidal Current Models — Europe

Copernicus IBI — Iberian-Biscay-Ireland — 3 km — 5 days

Copernicus ENWS — NW Shelf / North Sea — 2 km — 5 days

Copernicus BALTIC — Baltic Sea — 4 km — 5 days

Copernicus MED — Mediterranean — 5 km — 5 days

SHOM Manche-Gascogne — Channel & Biscay — 2 km — 5 days

SHOM Méditerranée Nord — NW Mediterranean — 2 km — 5 days

IFREMER — France coasts (10 zones) — 250m to 3 km — 4 days

🔵 Oceanic and tidal Current Models — Americas

MSC Saint Laurent — St. Lawrence / Atlantic Canada — 1 km — 84 hrs

NCOM Alaska - N. Calif — Alaska to N. California — 4 km — 90 hrs

NCOM Caribbean — Gulf of Mexico & Caribbean — 3 km — 90 hrs

NCOM Hawaii — Hawaii — 4 km — 90 hrs

NCOM South California — Southern California — 4 km — 90 hrs

NCOM US East Coast — US East Coast — 4 km — 90 hrs

Read also: Why are there global models and regional models

Question 3

How to Read Marine Weather Charts ?

Henri · Accepted Answer

How to Read Marine Weather Charts (Surface Analysis Charts)

Surface analysis charts are essential tools for any sailor. They provide a synoptic view of current weather conditions and help anticipate weather changes. This guide explains how to interpret the symbols and information on these charts.

What is a Surface Analysis Chart?

A Surface Analysis Chart is a representation of weather conditions at the Earth's surface at a given time. These charts are produced by national weather services such as NOAA (USA), the Met Office (UK), or Météo-France.

They use a combination of lines, symbols, and color codes to represent:

Pressure systems (highs and lows)
Weather fronts
Isobars (lines of equal pressure)
Weather station observations
Precipitation areas

NOAA Atlantic Surface Analysis Chart Example — North Atlantic Surface Analysis Chart - NOAA Ocean Prediction Center

Pressure Systems: Highs (H) and Lows (L)

Pressure systems are the main drivers of weather. They are indicated by the letters H (High pressure) and L (Low pressure).

High Pressure (H) - Anticyclone

H

Symbol: H (blue) with central pressure in millibars (e.g., 1035)

Characteristics: Air descends and spreads out, creating divergent winds. Clockwise rotation (Northern Hemisphere).

Associated weather: Generally stable conditions, clear skies, light to moderate winds, good visibility.

Low Pressure (L) - Depression

L

Symbol: L (red) with central pressure in millibars (e.g., 995)

Characteristics: Air converges toward the center and rises, creating clouds. Counter-clockwise rotation (Northern Hemisphere).

Associated weather: Unsettled weather, clouds, precipitation, strong winds. The lower the pressure, the more intense the storm.

💡 Navigation tip: A low with pressure below 980 mb is considered deep. NOAA charts sometimes indicate "GALE" (34-47 knots), "STORM" (48-63 knots), or "HURRICANE FORCE" (≥64 knots) near intense lows.

Isobars: Lines of Equal Pressure

Isobars are the thin lines connecting points of equal atmospheric pressure. They are typically spaced 4 millibars apart (1008, 1012, 1016, 1020 mb, etc.).

Key rule: Isobar spacing indicates wind strength:

Closely spaced isobars	→	Strong gradient = Strong winds
Widely spaced isobars	→	Weak gradient = Light winds

Chart with isobars — Atlantic surface analysis - Source: NOAA

💡 Buys-Ballot's Law: In the Northern Hemisphere, if you stand with your back to the wind, low pressure is always on your left. Wind blows parallel to isobars (with a slight angle toward low pressure due to friction).

Weather Fronts

Fronts are boundaries between different air masses. Their passage typically brings significant changes in temperature, wind direction, and weather conditions.

Cold Front

Symbol: Blue line with triangles pointing in the direction of movement

Description: Cold air mass pushing into warm air. Cold fronts move faster (25-30 knots) because the denser cold air undercuts the warm air.

Weather at passage: Thunderstorms or intense but brief showers, rapid wind shift (SW → NW), sharp temperature drop, quick clearing after passage.

Warm Front

Symbol: Red line with half-circles pointing in the direction of movement

Description: Warm air mass sliding over cold air. Slower (10-15 knots) because warm air must ride up over cold air.

Weather at passage: Prolonged steady precipitation, stratiform clouds (cirrus → altostratus → nimbostratus), reduced visibility, possible fog, gradual temperature rise.

Stationary Front

Symbol: Alternating blue triangles and red half-circles on opposite sides of the line

Description: Two air masses that aren't moving relative to each other. Can persist for several days.

Associated weather: Prolonged overcast conditions, persistent precipitation over the area, stagnant conditions.

Occluded Front

Symbol: Purple line with alternating triangles and half-circles on the same side

Description: The faster cold front catches up to the warm front. Warm air is lifted aloft.

Associated weather: Mixed conditions, varied precipitation. Significance: The low is reaching maturity and beginning to weaken.

Other Boundaries

Trough

Symbol: Brown/orange dashed line in a U or V shape, often marked "TROF"

Description: Elongated area of relatively low pressure, without being a true front.

Associated weather: Atmospheric instability, wind convergence, risk of thunderstorms or unsettled weather.

Squall Line

Symbol: Line with two red dots, often marked "SQLN"

Description: Organized line of thunderstorms, often located ahead of a cold front.

⚠️ DANGER: Violent winds, possible hail, destructive gusts. Potentially dangerous conditions for navigation!

Dry Line

Symbol: Orange/brown line with half-circles pointing toward moist air

Description: Boundary between dry continental air and moist maritime air (common in the US between Gulf of Mexico air and Southwest desert air).

Associated weather: Violent thunderstorm development along the line, especially in spring/summer.

Tropical wave

Symbol: Wide dotted red line.

Description: Rainy and stormy front moving from east to west in the intertropical zone. Frequent during the hurricane season between Africa and the Caribbean.

Associated weather: Squalls, sometimes intense, which can develop into tropical storms and then hurricanes as they progress.

📥 Complete reference: Official WPC/NOAA Front Legend

Weather Station Observations (Station Plots)

Detailed charts display weather station observations as station plots. These compact symbols summarize a lot of information at a glance.

Station plot example — Complete station plot - Source: NOAA JetStream

Station Plot Elements

Position	Information
Center	Cloud cover (● overcast, ◐ partly cloudy, ○ clear)
Upper left	Temperature (°F or °C)
Lower left	Dew point
Right	Pressure (last 3 digits: 218 = 1021.8 mb)
Extending line	Wind direction (where it's coming from)
Barbs	Wind speed (see below)

Reading Wind Barbs

Wind barbs indicate wind speed. Add the symbols together to get the total speed:

💡 Example: 1 pennant + 2 full barbs + 1 half barb = 50 + 20 + 5 = 75 knots

Precipitation Symbols

📥 Download: Complete Weather Symbol Guide (PDF) - NOAA

Understanding "Ahead" and "Behind" a Front

These terms refer to front movement, not geographic direction:

Term	Meaning	Example (Cold Front)
Ahead of the front	In front of the frontal movement	In the warm air mass
Behind the front	After the front has passed	In the cold air mass

💡 Practical application: If a forecast says "showers behind the cold front," expect precipitation AFTER the front passes through your location.

Common Units

Measurement	Unit	Conversion
Pressure	millibars (mb) or hectopascals (hPa)	1 mb = 1 hPa = 0.0295 inHg
Wind speed	knots (kt)	1 kt = 1.15 mph = 1.85 km/h
Temperature	°F (US) or °C (international)	°C = (°F - 32) × 5/9

Chart Sources and Frequency

Source	Coverage	Update Frequency
NOAA OPC	Atlantic, Pacific, Arctic	Every 6 hours (00, 06, 12, 18 UTC)
NOAA WPC	North America	Every 3 hours
Met Office	North Atlantic, Europe	Every 6 hours
BOM	Southern Hemisphere	Every 6 hours

Technical References

Official documentation:

NOAA Unified Surface Analysis Manual (PDF) - Complete 33-page technical reference
NOAA JetStream - Surface Weather Maps - Official NOAA online tutorial
WPC Front Codes - Official front symbol reference

Additional learning resources:

How to read Surface Weather Maps (NOAA JetStream) - Official NOAA guide with illustrations
Surface Weather Plots (NOAA JetStream) - Station plot details

Question 4

Glossary of marine terms in NavimetriX

Henri · Accepted Answer

📘 This glossary brings together the main terms used in the Navimetrix application and its FAQs. It helps users better understand concepts related to navigation, routing, and marine weather.

Course Over Ground (COG)

The actual direction of the boat’s movement over the seabed, expressed in degrees relative to true north. It differs from the compass heading when there is drift caused by wind or current.

Speed Over Ground (SOG)

The boat’s actual speed relative to the ground (not the water). Calculated by GPS, it includes the effect of currents.

Heading (HDG)

The direction in which the boat’s bow is pointing, measured relative to true or magnetic north.

True Wind Angle (TWA)

The angle between the boat’s axis and the true wind direction. It is calculated from the apparent wind and the boat’s speed.

True Wind Speed (TWS)

The wind speed derived from the apparent wind and the boat’s speed. It represents the actual wind strength on the sea surface.

Apparent Wind Angle (AWA)

The wind angle felt on board, influenced by the boat’s motion. Measured relative to the boat’s centerline.

Apparent Wind Speed (AWS)

The wind speed felt on the boat, resulting from the combination of the true wind and the boat’s speed.

Velocity Made Good (VMG)

The useful component of the boat’s speed, indicating the effective progress toward the destination or upwind.

Closest Point of Approach (CPA)

The point at which two vessels will be at their minimum distance from each other, based on their current courses and speeds.

Time to CPA (TCPA)

The time remaining before reaching the CPA, used for collision avoidance and AIS alarms.

Bearing

The angle between north and the direction of an observed object from the boat. Used to determine the relative position of a target or coastline.

Depth

The water depth below the keel, measured by an echo sounder. A key parameter for safe navigation.

Waypoint (POI / Waypoint)

A geographic point used to define a route or a key position. In Navimetrix, POIs represent these waypoints.

GRIB File (Gridded Binary)

A standard file format containing numerical weather forecasts (wind, waves, pressure, temperature, etc.).

Isochrone

A curve connecting all possible boat positions at a given time according to the predicted weather conditions.

Routing

The calculation of an optimal route considering wind, waves, currents, and the boat’s performance.

Polar

A performance curve showing the boat’s speed as a function of wind angle and wind strength. It forms the basis for the routing engine.

Estimated Time of Arrival (ETA)

The predicted time of arrival at the destination, calculated from the remaining distance and the average speed.

Sea State

A description of the waves and swell (height, direction, period). Used to assess routing comfort and safety.

Swell

A regular train of waves formed by distant winds. It differs from the wind sea, which is generated locally.

Significant Wave Height

The average height of the highest one-third of waves, the main indicator of overall sea conditions.

Currents

Water movements caused by tides or ocean circulation. They affect the boat’s speed and trajectory.

Tide

Variation in sea level caused by the gravitational attraction of the Moon and the Sun. It influences depth and coastal currents.

What weather and ocean models are available in NavimetriX?

What weather and ocean models are available in NavimetriX?

🌍 Atmospheric Models — Global

🇪🇺 Atmospheric Models — Europe

🌎 Atmospheric Models — Americas

🌏 Atmospheric Models — Pacific & Indian Ocean

🌊 Wave Models (Sea State)

🔵 Oceanic Current Models — Global

🔵 Oceanic and tidal Current Models — Global

🔵 Oceanic and tidal Current Models — Europe

🔵 Oceanic and tidal Current Models — Americas

Contact

Politique de confidentialité

Conditions Générales d’utilisation

What weather and ocean models are available in NavimetriX?

What weather and ocean models are available in NavimetriX?

🌍 Atmospheric Models — Global

🇪🇺 Atmospheric Models — Europe

🌎 Atmospheric Models — Americas

🌏 Atmospheric Models — Pacific & Indian Ocean

🌊 Wave Models (Sea State)

🔵 Oceanic Current Models — Global

🔵 Oceanic and tidal Current Models — Global

🔵 Oceanic and tidal Current Models — Europe

🔵 Oceanic and tidal Current Models — Americas

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