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This nowCOAST™ time-enabled map service provides maps depicting the geographic coverage of the latest NOAA/National Weather Service (NWS) Watches, Warnings, Advisories, and Statements for long-duration hazardous weather, marine weather, and hydrological, oceanographic, wildfire, air quality, and ecological conditions which may affect or are presently affecting inland, coastal, and maritime areas. A few examples include Gale Watch, Gale Warning, High Surf Advisory, High Wind Watch, Areal Flood Warning, Coastal Flood Watch, Winter Storm Warning, Wind Chill Advisory, Frost Advisory, Tropical Storm Watch, Red Flag Warning, Air Stagnation Warning, and Beach Hazards Statement. A complete list is given in the Background Information section below. The coverage areas of these products are usually defined by county or sub-county boundaries. The colors used to identify the different watches, advisories, warnings, and statements are the same colors used by the NWS on their map at http://www.weather.gov. The NWS products for long-duration hazardous conditions are updated in the nowCOAST™ map service approximately every 10 minutes. For more detailed information about layer update frequency and timing, please reference the nowCOAST™ Dataset Update Schedule.
NWS watches depict the geographic areas where the risk of hazardous weather or hydrologic events has increased significantly, but their occurrence, location, and/or timing is still uncertain. A warning depicts where a hazardous weather or hydrologic event is occurring, is imminent, or has a very high probability of occurring. A warning is used for conditions posing a threat to life or property. Advisories indicate where special weather conditions are occurring, imminent, or have a very high probability of occurring but are less serious than a warning. They are for events that may cause significant inconvenience, and if caution is not exercised, could lead to situations that may threaten life and/or property. Statements usually contain updated information on a warning and are used to let the public know when a warning is no longer in effect. All of these products are issued by the NWS regional Weather Forecast Offices (WFOs).
NWS watches, warnings, and advisories (WWA) are organized on the nowCOAST™ map viewer and within this map service by hazardous condition/threat groups and then by the geographic area (i.e. coastal & inland, immediate coast or maritime) for which the WWA product is targeted.
The Storm Surge Watch and Storm Surge Warning, which are included in the Flooding Hazards - Coastal Areas layer, are generated via a collaborative process between the National Hurricane Center (NHC) and Weather Forecast Offices (WFOs). The primary objective guidance for the watch/warning will be P-Surge, an ensemble-based probabilistic system driven by the Sea, Lake, and Overland Surges from Hurricanes (SLOSH) model, the latest NHC official tropical cyclone forecast, and the typical errors of the NHC forecasts. The watch and/or warning are displayed on nowCOAST at their full native spatial resolution.
For descriptions of individual NWS watches, warnings, and advisories please see Section 2 of the NWS Reference Guide available at http://www.nws.noaa.gov/om/guide/Section2.pdf.
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:
NWS Instructions and other directives are available at http://www.nws.noaa.gov/directives/.