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nowcoast/guidance_model_coastalocean_estofs_time (MapServer)

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Service Description:
Last Revised: February 2018

Map Information

This nowCOAST™ time-enabled map service provides maps of the latest nowcasts and forecast guidance of combined (tides + wind driven) water level and storm surge from the NOS Extratropical Surge and Tide Operational Forecast System (ESTOFS) at 3 hour increments out to 180 hours. The water levels are referenced to MSL. For water level, a color scale from pink to red is used to depict water levels from -14 ft to +12 ft at mainly 0.5 ft increments. The maps of ESTOFS forecast guidance are updated in the nowCOAST™ map service four times per day. For more detailed information about layer update frequency and timing, please reference the nowCOAST™ Dataset Update Schedule.

Background Information

ESTOFS is designed to provide water surface elevations caused by storm surge and astronomical tide to the NCEP WAVEWATCH III (WW3) wave model for coupling wave and water level predictions. ESTOFS set-up is designed to mimic the WW3 model. ESTOFS is based on the Advanced Circulation (ADCIRC) finite element, numerical ocean circulation or hydrodynamic prediction model. The ESTOFS grid domains cover the Western North Atlantic out to 60 degrees West longitude including the Gulf of Mexico and Puerto Rico, the Eastern and Central Pacific Ocean including the Gulf of Alaska and the Hawaiian Islands, and the Micronesia region (Palau, Guam and the Marianas, Federated States of Micronesia, Marshall Islands, and Wake Island). ESTOFS has an average spatial horizontal resolution at the coast of about 3 km with resolution in the nearshore of about 200 m. The overland resolution extends to 10 m elevation relative to NAVD88. ESTOFS has four forecast cycles per day (0000, 0600, 1200, and 1800 UTC) which generate water level forecast guidance out to 180 hours. The forecast cycle uses 3-hourly forecast guidance of surface winds and sea-level pressure from NWS/NCEP Global Forecast System (GFS) T1534. For forcing at the lateral ocean boundary, the OFS uses harmonic tidal constituents from the global tidal model, TPXO 6.2 to specify the tidal water surface fluctuations, while tidal potential is applied within the interior of the domain. There is no river inflow. Each forecast cycle is preceded with a 6-hr long nowcast cycle. The final nowcast serves as the initial conditions for each forecast cycle. The nowcoast cycle is driven by very short-range forecasts of surface wind and sea level pressure from GFS and tide information from the global tide model. ESTOFS was developed and evaluated by NOAA/NOS Coast Survey Development Laboratory/Coastal Marine Modeling Branch in collaboration with NWS/NCEP Environmental Modeling Center/Marine Modeling and Analysis Branch. ESTOFS became operational in September 2012. ESTOFS is run on the NOAA Weather and Climate Operational Supercomputer System (WCOSS) operated by NCEP Central Operations. ESTOFS should not be used for tropical cyclone events. For more information, please see and

Time Information

This map service is time-enabled, meaning that each individual layer contains time-varying data and can be utilized by clients capable of making map requests that include a time component.

In addition to ArcGIS Server REST access, time-enabled OGC WMS 1.3.0 access is also provided by this service.

This particular service can be queried with or without the use of a time component. If the time parameter is specified in a request, the data or imagery most relevant to the provided time value, if any, will be returned. If the time parameter is not specified in a request, the latest data or imagery valid for the present system time will be returned to the client. If the time parameter is not specified and no data or imagery is available for the present time, no data will be returned.

This service is configured with time coverage support, meaning that the service will always return the most relevant available data, if any, to the specified time value. For example, if the service contains data valid today at 12:00 and 12:10 UTC, but a map request specifies a time value of today at 12:07 UTC, the data valid at 12:10 UTC will be returned to the user. This behavior allows more flexibility for users, especially when displaying multiple time-enabled layers together despite slight differences in temporal resolution or update frequency.

When interacting with this time-enabled service, only a single instantaneous time value should be specified in each request. If instead a time range is specified in a request (i.e. separate start time and end time values are given), the data returned may be different than what was intended.

Care must be taken to ensure the time value specified in each request falls within the current time coverage of the service. Because this service is frequently updated as new data becomes available, the user must periodically determine the service's time extent. However, due to software limitations, the time extent of the service and map layers as advertised by ArcGIS Server does not always provide the most up-to-date start and end times of available data. Instead, users have three options for determining the latest time extent of the service:

  1. Issue a returnUpdates=true request (ArcGIS REST protocol only) for an individual layer or for the service itself, which will return the current start and end times of available data, in epoch time format (milliseconds since 00:00 January 1, 1970). To see an example, click on the "Return Updates" link at the bottom of the REST Service page under "Supported Operations". Refer to the ArcGIS REST API Map Service Documentation for more information.
  2. Issue an Identify (ArcGIS REST) or GetFeatureInfo (WMS) request against the proper layer corresponding with the target dataset. For raster data, this would be the "Image Footprints with Time Attributes" layer in the same group as the target "Image" layer being displayed. For vector (point, line, or polygon) data, the target layer can be queried directly. In either case, the attributes returned for the matching raster(s) or vector feature(s) will include the following:
    • validtime: Valid timestamp.
    • starttime: Display start time.
    • endtime: Display end time.
    • reftime: Reference time (sometimes referred to as issuance time, cycle time, or initialization time).
    • projmins: Number of minutes from reference time to valid time.
    • desigreftime: Designated reference time; used as a common reference time for all items when individual reference times do not match.
    • desigprojmins: Number of minutes from designated reference time to valid time.
  3. Query the nowCOAST™ LayerInfo web service, which has been created to provide additional information about each data layer in a service, including a list of all available "time stops" (i.e. "valid times"), individual timestamps, or the valid time of a layer's latest available data (i.e. "Product Time"). For more information about the LayerInfo web service, including examples of various types of requests, refer to the nowCOAST™ LayerInfo Help Documentation


Map Name: NOAA NOS Extratropical Surge and Tide Operational Forecast System (ESTOFS) Forecast Guidance (Time Enabled)


All Layers and Tables

Dynamic Legend

Dynamic All Layers

Layers: Description:


Spatial Reference: 102100  (3857)

Single Fused Map Cache: false

Initial Extent: Full Extent: Time Info: Units: esriMeters


Document Info: Supports Dynamic Layers: true

MaxRecordCount: 1000

MaxImageHeight: 4096

MaxImageWidth: 4096

Supported Query Formats: JSON, AMF, geoJSON

Min Scale: 0

Max Scale: 0

Supports Datum Transformation: true

Child Resources:   Info   Dynamic Layer

Supported Operations:   Export Map   Identify   Find   Return Updates