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This nowCOAST™ time-enabled map service provides maps depicting the latest official NWS tropical cyclone forecast tracks and watches and warnings for all active systems in the Atlantic, Caribbean Sea, Gulf of Mexico, Eastern Pacific Ocean, and Central Pacific Ocean. The map layers display the cyclone's present location, past locations (best track), maximum estimated sustained surface wind and wind gusts (knots), mean sea level pressure (millibars), forecasts of the cyclone's surface positions, maximum sustained winds and gusts at 12, 24, 36, 48, 72, 96 and 120 hours, and uncertainty of the forecast track depicted as a cone. Best track information is available for all storms in the Atlantic, Caribbean Sea, Gulf of Mexico and Eastern Pacific Ocean but not for storms in the Central Pacific Ocean. The track forecasts are based on information from the NWS/National Hurricane Center (NHC) and NWS/Central Pacific Hurricane Center (CPHC) Tropical Cyclone Public Advisories. This map service is updated on nowCOAST every 10 minutes in order to obtain and display the latest information from the regularly scheduled NHC and CPHC tropical cyclone public advisories as well as any intermediate or special public advisories. For more detailed information about layer update frequency and timing, please reference the nowCOAST™ Dataset Update Schedule.
The regularly scheduled advisories are issued every six hours at 0300, 0900, 1500 and 2100 UTC, and intermediate public advisories are issued as needed. Public advisories for Atlantic tropical cyclones are normally issued every six hours at 5:00 AM EDT, 11:00 AM EDT, 5:00 PM EDT, and 11:00 PM EDT (or 4:00 AM EST, 10:00 AM EST, 4:00 PM EST, and 10:00 PM EST). Public advisories for Eastern Pacific tropical cyclones are normally issued every six hours at 2:00 AM PDT, 8:00 AM PDT, 2:00 PM PDT, and 8:00 PM PDT (or 1:00 AM PST, 7:00 AM PST, 1:00 PM PST, and 7:00 PM PST). Public advisories for Central Pacific tropical cyclones are issued every six hours at 5:00 AM HST, 11:00 AM HST, 5:00 PM HST, and 11:00 PM HST (or 4:00 AM HDT, 10:00 AM HDT, 4:00 PM HDT, and 10:00 PM HDT). Intermediate public advisories may be issued every three hours when coastal watches or warnings are in effect, or every two hours when coastal watches and warnings are in effect and land-based radars have identified a reliable storm center. Additionally, special public advisories may be issued at any time due to significant changes in warnings or with the tropical cyclone (e.g. intensity, direction of motion).
The track and intensity forecasts represent the official forecast of center surface positions at 0-hour (initial location), 12, 24, 36, 48, 72, 96, and 120 hours as well as the connecting track. The international tropical cyclone symbols for Tropical Depression, Tropical Storm, or Hurricane are used to indicate the tropical cyclone category based on the NHC's forecast intensity at the different forecast projection hours. The labels of the predicted maximum sustained surface wind speed and gusts (in knots) are shown for each of the 12 through 120 hour forecast center positions. In addition, the estimated observed maximum sustained surface wind speed, wind gusts, and lowest mean sea level pressure (MSLP, shown in millibars) of the initial (0-hour) position are also plotted on the map. NHC states that wind forecasts have an uncertainty near 20 knots each day. The maximum sustained surface wind is defined as the highest 1-minute sustained surface wind speed occurring within the circulation of the tropical cyclone at the standard meteorological measurement height of 10 m (33 ft) in an unobstructed exposure. The predicted gust is the wind peak during a 3-5 second time period. The value of the maximum 3-second gust over a 1-minute period is on the order of 1.3 times (or 30% higher) than the 1-minute sustained wind speed.
The forecast position symbols include the Saffir-Simpson Hurricane wind scale. This scale produces a 1 to 5 rating based on a hurricanes sustained wind speed, and estimates potential property damage.
|Category||Sustained Winds||Types of Damage Due to Hurricane Winds|
|Very dangerous winds will produce some damage: Well-constructed frame homes could have damage to roof, shingles, vinyl siding and gutters. Large branches of trees will snap and shallowly rooted trees may be toppled. Extensive damage to power lines and poles likely will result in power outages that could last a few to several days.|
|Extremely dangerous winds will cause extensive damage: Well-constructed frame homes could sustain major roof and siding damage. Many shallowly rooted trees will be snapped or uprooted and block numerous roads. Near-total power loss is expected with outages that could last from several days to weeks.|
|Devastating damage will occur: Well-built framed homes may incur major damage or removal of roof decking and gable ends. Many trees will be snapped or uprooted, blocking numerous roads. Electricity and water will be unavailable for several days to weeks after the storm passes.|
|Catastrophic damage will occur: Well-built framed homes can sustain severe damage with loss of most of the roof structure and/or some exterior walls. Most trees will be snapped or uprooted and power poles downed. Fallen trees and power poles will isolate residential areas. Power outages will last weeks to possibly months. Most of the area will be uninhabitable for weeks or months.|
|157 mph or higher
137 kt or higher
252 km/h or higher
|Catastrophic damage will occur: A high percentage of framed homes will be destroyed, with total roof failure and wall collapse. Fallen trees and power poles will isolate residential areas. Power outages will last for weeks to possibly months. Most of the area will be uninhabitable for weeks or months.|
The map service also provides maps of the "working best track" or "best track" for presently active tropical cyclones in the Atlantic, Caribbean Sea, Gulf of Mexico, and Eastern Pacific Oceans. This information is not presently available for cyclones within the CPHC's Central Pacific Ocean area of responsibility. The best track information represents the forecasters' best estimates of the location, intensity, and size of a tropical cyclone while the cyclone is still an active weather system. According to the NHC, the "best track wind swath shows how the size of the storm has changed and the areas potentially affected so far by sustained winds of tropical storm force (34 knots), 50 knot, and hurricane force (64 knot) from a tropical cyclone. These data are based on the wind radii contained in the Automated Tropical Cyclone Forecasting (ATCF) system's working best track. Users are reminded that the best track wind radii represent the maximum possible extent of a given wind speed within particular quadrants around the tropical cyclone. As a result, not all locations falling within the swaths will have experienced the indicated sustained wind speeds. These data are intended for geographic display and analysis at the national level and for large regional areas. The data should be displayed and analyzed at scales "appropriate for 1:2,000,000-scale data."
The dashed blue line represents the NHC forecast track from 0 to 120 hours. The track lines are provided as an aid in the visualization of official NHC track forecasts. Since there are an infinite number of ways to connect a set of forecast points and the motion of cyclones in between forecast projections, the lines should not be interpreted as representing a specific forecast for the cyclone location in between official forecast points. It is important to note that a tropical cyclone is not a point; the effects of a tropical cyclone can span many hundreds of miles from the system's center. The area experiencing tropical storm or hurricane winds can extend well beyond the greenish areas depicting the most likely track area of the center. In addition, the strength of winds can vary greatly in different quadrants of any tropical cyclone.
The forecast uncertainty is conveyed by the track forecast "cone," frequently referred to as the Cone of Uncertainty. The cone represents the probable track of the center of a tropical cyclone. The transparent white area enclosed with a black outline depicts the track forecast uncertainty for Days 1-5. The cone is created by first placing a set of imaginary circles along the forecast track at the 12, 24, 36, 48, 72, 96 and 120 hour forecast center positions. The size of each circle is set so that two-thirds of historical official forecast errors over a 5-year sample fall within the circle. The cone is then formed by smoothly connecting the area swept out by the set of circles. Based on error statistics from 2012-2016, radii of NHC forecast cone circles in the Atlantic Basin for 2017 ranged from 45 nautical miles on Day 1 to 211 nautical miles on Day 5. For other forecast periods, please reference the Definition of the NHC Track Forecast Cone.
The tropical cyclone watches and warnings depict the geographic extent of tropical storm and hurricane watches and warnings along the immediate coastline using the following color scheme: hurricane warning - red, hurricane watch - pink, tropical storm warning - blue, and tropical storm watch - yellow. The criteria for the different types of watches and warnings are the following:
The coastal areas placed under these watches or warnings are identified through the use of "breakpoints." A tropical cyclone breakpoint is defined as an agreed upon coastal location that can be chosen as one of two specific end points or designated places between which a tropical storm/hurricane watch/warning is in effect. NWS designates these locations along the U.S. East, Gulf, and California coasts, Puerto Rico, and Hawaii.
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: