Tropical Cyclone Watch/Warning (TCV)
1. New in 2017
Effective on or around June 1, 2017, the National Weather Service (NWS) will introduce new storm surge
watches and warnings for Atlantic tropical cyclones affecting the continental U.S. Information about the
new NWS storm surge watch/warning can be found in Service Change Notice 17-6:
These additions to the NWS product suite require changes to NWS Tropical Cyclone Watch/Warning (TCV)
products and Hurricane Local Statement (HLS) products. All TCV products issued by the NWS during the 2017
season for tropical cyclones originating in the Atlantic basin affecting the continental U.S. will include
Valid Time Event Code (VTEC) for storm surge watches and/or warnings when conditions warrant. TCVs issued by the National Hurricane Center
will not include storm surge watches and/or warnings for Puerto Rico or the U.S. Virgin Islands.
TCV products from Atlantic basin WFOs along the Gulf and East Coast as well as from the National Hurricane Center will
contain Universal Geographic Code (UGC) and the following Valid Time Event Codes (VTEC):
TR.A - Tropical Storm Watch
TR.W - Tropical Storm Warning
HU.A - Hurricane Watch
HU.W - Hurricane Warning
SS.A - Storm Surge Watch
SS.W - Storm Surge Warning
Information about VTEC can be found here:
In 2017, the National Hurricane Center (NHC) expanded the tropical cyclone watch and warning information available in its National Tropical Cyclone Watch/Warning (TCVAT#) products issued for Atlantic tropical cyclones. In past hurricane seasons, the National TCV products for the Atlantic basin contained only the tropical cyclone wind watches and warnings along coastal segments issued by NHC. The National TCV products from NHC for the continental US east and gulf coasts will include all NWS-issued zone-based tropical cyclone wind and storm surge watches and warnings from both NHC and local Weather Forecast Offices (WFOs) and will no longer contain breakpoint information. The National TCV for Puerto Rico and the U.S. virgin islands will not include storm surge watches and warnings. It should be noted that the process to compile the complete set of coastal and inland watches and warnings will result in a modest delay in the availability of the NHC-issued National TCV, which is expected to be available within 15 minutes of the nominal advisory time for routine advisories. In some circumstances, such as for the issuance of special advisories, it may be delayed as much as 45 minutes after the advisory time. Public Information Statements from NHC (PNSNHC), as well as social media, may be used to communicate significant issuance delays for any NHC products.
These changes to the NHC-issued National TCV are not applicable to the Pacific basin. National TCV products issued for the Pacific basin from NHC (TCVEP#) and the Central Pacific Hurricane Center (TCVCP#) will continue to use only coastal segment or island VTEC as appropriate at this time.
The TCV issued by NHC provides VTEC data for tropical cyclone watches and warnings. This product is distinct from the Hurricane Local Watch/Warning Product or WFO TCV described in NWSI 10-601 section 1.1. The specific content, methods of preparation, and formats of the National TCV vary by basin:
The National TCV issued by NHC for the Atlantic basin summarizes all inland and coastal US tropical cyclone wind and storm surge watches and warnings and represents a compilation of the land-based tropical cyclone watch/warning VTEC information provided in the applicable WFO TCV products. The representation of watches/warnings in the Atlantic basin TCV is provided only in terms of zones; as a result the TCV can only convey an approximate description of the watch/warning areas. The precise lateral extent of tropical cyclone wind watches and warnings along the coastline is specified by breakpoints in the Tropical Cyclone Public Advisory. The precise extent of storm surge watches/warnings is specified in gridded form through the National Digital Forecast Database (NDFD). The Atlantic National TCV will contain a disclaimer indicating where the precise extent of tropical cyclone watches and warnings can be found.
The Atlantic basin TCV will contain the full complement of VTEC actions as described by NWSI10-1703. Additional information on UGC and VTEC can be found in NWS Instruction (NWSI) 10-1701 and NWSI 10-1703,
The TCV issued by NHC for the eastern Pacific basin lists coastal tropical cyclone wind watches/warnings for southern California, but does not include inland watches/warnings issued by WFOs. The precise extent of the coastal wind watch/warnings are conveyed in the eastern Pacific National TCV by providing the latitudes and longitudes of the watch/warning breakpoints.The eastern Pacific basin TCVs will use the following three actions codes:
NEW is used when a watch or warning is first issued for a given geographic area. The geographic areas include the southern California coast. NEW is also used for upgrades and downgrades (e.g., Tropical Storm Watch to Tropical Storm Warning, Hurricane Warning to Tropical Storm Warning, Tropical Storm Warning to Hurricane Watch, etc.).
CON is used if there are no changes in the watch/warning for a given geographic area.
CAN is used to cancel an area if there is no longer a watch/warning in effect for the geographic area or if the watch/warning is upgraded/downgraded. (e.g., an area once under a Tropical Storm Warning is now under a Hurricane Warning: the VTEC will show the area as CAN for the Tropical Storm Warning and NEW for the Hurricane Warning).
Examples of the WFO and NHC issued TCV products with the new format can be found in the sections below.
3. Product Examples
- NHC-Issued TCV with Storm Surge Watch/Warning – Example 1
- NHC-Issued TCV with Storm Surge Watch/Warning – Example 2
- NHC-Issued TCV with Storm Surge Watch/Warning – Example 3
- NHC-Issued TCV without Storm Surge Watch/Warning
The following are examples of the changes to the WFO-issued tropical product to incorporate watches (SS.A) and warnings (SS.W) for Storm Surge. This product is not issued by NHC.