ArcGIS Online map viewer
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ArcGIS Online map viewer
This nowCOAST™ time-enabled map service provides maps depicting the
geographic coverage of the latest NOAA/National Weather Service (NWS) Warnings
for short-duration hazards for inland, coastal, and maritime areas which are in
progress, imminent, or have a very high probability of occurring. These hazards
include severe thunderstorms (damaging winds, large hail), tornadoes,
waterspouts, flash floods, and extreme winds associated with major land-falling
hurricanes. Specifically, the layer includes the following warnings: Special
Marine Warnings (winds of 34 knots, 3/4 inch diameter hail, waterspouts),
Severe Thunderstorm Warnings (winds of 58 MPH or greater, or large hail of 1
inch or greater in diameter), Tornado Warnings, Flash Flood Warnings, and
Extreme Wind Warnings (sustained surface winds of 115 MPH or greater during
major [Category 3 or higher] land-falling hurricane within one hour). The
colors used to identify the different warnings are the same colors used by the
NWS on their map at
The map is updated in the nowCOAST™ map service once every minute.
For more detailed information about layer update frequency and timing, please reference the
nowCOAST™ Dataset Update Schedule.
The NWS threat-based polygon or storm-based warnings are issued by NWS Weather
Forecast Offices (WFOs) to depict the type of short-duration weather or
hydrological hazard which is in progress, imminent or has a very high
probability of occurring for a specified geographic area. For Severe
Thunderstorm, Tornado, Flash Flood and Extreme Wind Warnings, the warnings are
not restricted to geopolitical boundaries. However, Special Marine Warnings are
issued for marine areas such as bays, harbors, sounds and coastal waters along
the U.S. coastline out to the NWS Offshore marine forecast zone. For Guam and
Pago Pago, American Samoa, the coastal waters extend out to the the NWS High
Seas marine forecast zone boundary.
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
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.
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
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.
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
nowCOAST™ LayerInfo Help Documentation
NWS, 2003: NWS Product Description Document for Special Marine Warning,
NWS, Silver Spring, MD.
NWS, 2005: NWS Instructions 10-511, WFO Severe Weather Products
Specification, NWS, Silver Spring, MD.
NWS, 2007: NWS Instructions 10-922, Weather Forecast Office Hydrologic
Products Specifications, NWS, Silver Spring, MD.
NWS, 2014: Extreme Wind Warning Product Description Document
NWS Instructions and other directives are available at http://www.nws.noaa.gov/directives/.
NOAA NWS Weather Warnings for Short-Duration Hazards in Inland, Coastal, and Maritime Areas (Time Enabled)
All Layers and Tables
Dynamic All Layers
NOAA/NOS/OCS nowCOAST and NOAA/NWS/SRH
Single Fused Map Cache:
Supported Image Format Types:
Title: NOAA/NWS Weather Warnings for Short-Duration Hazards in Inland, Coastal, and Maritime Areas (Time Enabled)
Supports Dynamic Layers:
Author: John G.W. Kelley
Comments: This time-enabled map service provides NOAA/National Weather Service warnings for short-duration hazards for inland, coastal, and maritime areas including severe thunderstorms (winds of = > 58MPH, large hail of =>1" in diameter), tornadoes, waterspouts, flash floods, and extreme winds (sustained winds of => 115MPH) associated with major land-falling hurricanes. Specifically, the layer includes Special Marine Warnings, Severe Thunderstorm Warnings, Tornado Warnings, Extreme Wind Warnings, and Flash Flood Warnings. These storm-based warnings or threat-based polygon warnings depict the specific meteorological or hydrological threat areas and are not restricted to geopolitical boundaries. The NWS warnings are updated in the nowCOAST map service every minute.
Subject: The map service provides NWS storm-based warnings for severe thunderstorms, tornadoes, flash floods, and extreme winds of major land-falling hurricanes.
Keywords: storm-based warnings,short-duration,special marine,severe weather,severe thunderstorms,tornadoes,damaging winds,large hail,waterspouts,flash floods,extreme winds during major land-falling hurricanes
Supported Query Formats:
JSON, AMF, geoJSON
Supports Datum Transformation: