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Marine Forecast Charts

Welcome to the latest version of Supercharts! A dynamic marine forecast charting tool based on GRADS software and data from NOAA's WAVEWATCHIII wave models, NOAA's Global Forecast System (GFS) and North American Mesoscale (NAM), a variety of charts can be created for any point on the globe. Here are the features of the system:

  • Marine forecast charts can be centered anywhere in the world.
  • The domain of the charts can be changed by the zoom in/out controls.
  • Dynamic Animations: Any chart you see can be animated.
  • Create your charts and save them in your own customized menu. The charting system is now available from your region home page.

Marine Forecast Chart Types:

Significant Wave Height

Significant wave height provided by the wavewatch model is the average of the highest 1/3 waves. Be aware this is just an average. Individual waves in a storm can be 1.5 to 2 times greater than the significant height.

10 Meter Winds

10-Meter Winds (about 33 feet above the ground) correspond to typically measured winds at weather stations. Gusts can be up to 1.5 times the wind reported.

Wave Period

(seconds) The interval between wave crests measured in seconds. Large, short period (<12 sec) swells can mean danger to small craft. Long period swells mean opportunity for surfers. You can see swells coming and going in the data by watching step changes in period. Each step means a new swell has become primary.

Relative Humidity

RH is a good predictor of cloud location and thickness. Areas of RH < 60% generally are clear or have partly cloud skies. Areas of 60-80% are generally overcast or mostly cloudy. Areas greater than 80% are overcast with a high likelihood of precipitation as RH approaches 100%.

Convective Available Potential Energy

(CAPE) CAPE represents the amount of energy a parcel might have if it were lifted. Often this reflects the strength of updrafts within a thunderstorm. CAPE values of greater than 2000 represent enough energy to produce thunderstorms. A value greater than 3000 represents enough energy to produce strong thunderstorms. Values < 1000 denote a relatively stable atmosphere.

Lifted Index

The LI field shows instability in the atmosphere. Where LI's are < 0 , thunderstorms are possible. The lower the number, the more unstable the atmosphere is and as a result, the stronger the thunderstorms could become. Values of -4 or lower indicate areas where severe thunderstorms are possible. Values > 10 indicate areas of stable weather where skies are generally clear.

2 Meter Dew Point Temperature

The dewpoint field shows the amount of moisture in the atmosphere. The higher the dewpoint, the higher the moisture content. Dewpoint temperatures are decent indicators of potential low temperatures. The morning temperatures will rarely drop below the dewpoint. where moisture is significant enough to fuel thunderstorm development. 59 F or 15 Celsius is a cutoff for strong thunderstorm development. Areas of dewpoints greater than 20 C can generate air mass thunderstorms which often aren't reliant on low level convergence for initial development.

2 Meter Above Ground Temperature

The temperature field shows the location of warm and cold air near the surface of the earth and can be used to locate surface fronts or estimate high and low temperatures. It should be noted, these are rough temperatures are won't reflect exact surface temperatures that would be reported at station locations.

Sea Level Pressure

Sea level pressure will detail the location and strength of high and low pressure systems as well as locate warm, cold and stationary fronts. The pressure contours or isobars are drawn every 4 millibars. Cold fronts generally follow the pressure trough flowing south and west from the low pressure system. Warm fronts can be located at times as pressure troughs going east out of a low but are generally hard to find. Surface winds are related to the packing of the pressure contours (isobars). The tighter the packing, the stronger the winds are.

Precipitation

Precipitation shows estimated 3 hour precipitation (liquid equivalent) for the 3 hour period prior to the valid time.

500 mb Vorticity

The vorticity field shows small eddies in the atmosphere that generally are not detectable on the standard height field. Values of 14 or higher highlight those eddies. The higher the vorticity, the higher the eddy. These eddies can help strengthen surface low pressure systems and induce precipitation and are often used as a predictive tool. Positive (or negative in the Southern Hemisphere) vorticity at 500 millibars is associated with cyclones or storms at upper levels, and will tend to coincide with troughs in the geopotential height field. Negative (positive in SH) vorticity is associated with calm weather, and will tend to coincide with ridges in the geopotential height field.

500 mb Height

The 500 mb level is often referred to as the steering level as most weather systems and precipitation follow the winds at this level. The winds follow the height contours and generally run from 30 to 100 knots. This level averages around 18,000 feet above sea level and is roughly half-way up through the weather producing part of the atmosphere called the troposphere.

500 mb Wind Vector

The vector field shows wind direction and speed. Often this can be used to qualitatively show areas of convergence and divergence. In the middle and upper levels of the troposphere, this can be an indicator of existing upward (from divergence) or downward (from convergence) air motion.

Precipitable Water

Precipitable water is the total depth of liquid water that would result if all water vapor contained in a vertical column of air could be "wrung out", leaving the air completely dry. It indicates the total humidity of the air above a location, and is a good indicator of the amount of moisture potentially available to supply rainfall.

Multi Channel Sea Surface Temp

(MCSST) The Naval Oceanographic Office operationally processes real-time Global Area Coverage Advanced Very-High Resolution Radiometer (AVHRR) data from POES NOAA-14 and NOAA-15. Over 300,000 global Multi-Channel Sea Surface Temperature (MCSST) retrievals are generated and distributed daily in less than 5 hours from the time the satellites acquire the data. Global match-ups of satellite retrievals with drifting buoy measurements of sea surface temperature consistently maintain a global root-mean-square difference error of less than 0.7 oC.

NOAA WAVEWATCH III AND GFS MODEL INFO

The operational ocean wave predictions of NOAA/NWS/NCEP are performed using the wave model WAVEWATCH III using operational products of NCEP as input. The wave model suite consists of global and regional implementations. Buoyweather wave forecast products are currently based on the global(NWW3) 1.25 X 1.0, the regional Western North Atlantic(WNA) .25 X .25, the regional Eastern North Pacific(ENP) .25 X .25. The models provide data for ocean regions only.

Global Forecast System (GFS), previously AVN & MRF, provides global data on a 1.0 X 1.0 degree grid. It covers everywhere in the world including land points.

The global NWW3 covers everywhere in the world between latitude 78 north and 78 south. The NWW3 grid points are only along whole latitudes and longitudes are spaced at 1.25 degree intervals.

The WNA Atlantic data covers the US east coast, Gulf of Mexico, Caribbean, and Central America from latitude 50 north to the equator and out to 30 west.

The ENP Pacific data cover the US west coast, Mexico, all Central America, and out to the Hawaiian Islands. It goes from 60 north to 5 north and extends out to 170 west.

Caution: The model may not provide valid data sometimes for large water areas inside barriers, such as reefs (e.g. Great Barrier Reef in Australia), coastal islands etc. Many small islands are invisible to the model. If you are on the leeward side of an island, forecasted winds and swell may be blocked. If you are in waters at risk of tropical storms, you cannot rely on this weather model for your storm forecast. Many tropical systems and squalls are too small to be picked up by the global model. Always use the text tropical storm outlooks from NOAA and the US Navy.

All the WAVEWATCH and GFS data updates 4 cycles per day. New data is available at (UTC) 08:00, 14:00, 20:00, 02:00. Buoyweather will occasionally have problems getting data from NOAA servers. These problems are beyond our control when their servers are down. Data updates are closely monitored. If the data hasn't updated, it means it's not available.

We've created some charts on the menu to get you started. You can adjust them to suite the needs of your location.

You should read the Guide to WAVEWATCH written by Hendrick Tolman, its creator. It tells you what you need to know about the WAVEWATCHIII model variables.

Long Range Marine Forecast Charts


Buoyweather premium members get fast, easy access to long range marine forecast charts, click for the details!

Buoyweather premium members receive instant 7-day marine weather forecasts, and dynamic weather forecast charts tailored to your location. Each marine weather buoy report comes with a complete set of marine forecast charts made for your selected point(s); including wave data, wind speed, surface pressure, precipitation, air temp, humidity, dew temp and much more.

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