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NOAA NOAA United States Department of Commerce

Tropical Cyclone Valid Time Event Code (VTEC)

Updated 9 January 2007


  1. Overview
  2. Product Description

2. Product Description

The product is issued by TPC/National Hurricane Center each time a tropical cyclone watch and/or warning is issued, continued, or discontinued for the Atlantic and Gulf coasts of the continental United States, and the coasts of Puerto Rico and the United States Virgin Islands. The product will use official hurricane breakpoints and their latitude and longitude as defined in NWSI 10-605:

In rare instances, other supplemental breakpoints, with their latitude and longitude, could be used.

A. Example of Product

500 PM EDT FRI JAN 5 2007


500 PM EDT FRI JAN 5 2007

FERNANDINA-BEACH-FL                 30.66N 81.44W
SOUTH-SANTEE-RIVER-SC               33.12N 79.27W


500 PM EDT FRI JAN 5 2007

NEW-SMYRNA-BEACH-FL                 29.03N 80.89W
FERNANDINA-BEACH-FL                 30.66N 81.44W


500 PM EDT FRI JAN 5 2007

SOUTH-SANTEE-RIVER-SC               33.12N 79.27W
CAPE-FEAR-NC                        33.85N 77.97W



B. Explanation of Code

1. On the Universal Geographic Code (UGC) line, the product purge/expiration time, the TPC/NHC tropical cyclone advisory package is routinely issued every six hours. Once watches/warnings are issued, intermediate public advisories will be transmitted every two or three hours but will only be accompanied by a TCV product if changes to the watches or warnings occur. The experimental TCV VTEC text product will be issued at a minimum of every six hours when noted U.S. watch/warnings are in effect. The purge/expiration time corresponds to the time of the next full forecast advisory package (e.g. 0300Z, 0900Z, 1500Z, 2100Z).

The TCV VTEC product will contain UGC for forecast zones for the affected WFOs. Marine zones will not be included.

The proposed text product will include watches/warnings for Puerto Rico and the U.S. Virgin Islands.

2. For 2007, the TCV product will be sent as O, operational mode.

3. Action Codes - Propose are the use of only three action codes: CAN, CON, NEW due to the complexity of tropical cyclone watches/warnings, and thus the difficulty of writing code for all the various scenarios.

Example. TPC/NHC issues an initial hurricane watch for area XYZ. A TCV is issued using the NEW action code. 12 hours later area XYZ is placed under hurricane warning. A TCV is issued to cancel the hurricane watch using the action code CAN. The same TCV message would also contain a NEW action code for the "new" hurricane warning for area XYZ.

4. Phenomenon codes: HU - Hurricane TR - Tropical Storm

5. The VTEC event tracking number (ETN) - 1st digit: basin indicator. 2nd-4th digits: storm ID.
Example: For storm #05 in Atlantic basin: 1005 (where 1 is Atlantic basin)
A TCV will only be produced if watches and/or warnings are issued for the U.S. mainland, Puerto Rico or U. S. Virgin Islands. Therefore, some ETNs may be skipped. This keeps the ETN always matching the storm number. Storm numbers are found in the mass news media dissemination headers of Tropical Cyclone Forecast/Advisory (TCM) products.

6. The VTEC event start time - Start times are zeroes except for NEW action codes.

7. The VTEC expiration time - Tropical cyclone products do not contain expiration times. The expiration time would consist of all zeros. Example: 000000T0000Z

8. TPC/NHC will always issue a final TCV, discontinuing all tropical cyclone watches/warnings.

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