Download the NHC Product Description User's Guide for all tropical cyclone-related
products.
Note: The products listed below are those used by the Hurricane Watch Net. For a complete listing of products issued by the National Hurricane Center,
please visit their website at
www.nhc.noaa.gov/aboutnhcprod.shtml
For a current listing of active storms, please visit our
home page. The most current data of products listed below can be found on our
Atlantic
Products and
Eastern Pacific Products pages.
Contents
Tropical Cyclone Public Advisory (TCP) - How To Read
World Meteorological Organization (WMO) and AWIPS (in parenthesis) headers:
WTNT31-35 KNHC (MIATCPAT1-5) – Atlantic
WTPZ31-35 KNHC (MIATCPEP1-5) – E. Pacific
The
Tropical Cyclone Public Advisory contains a list of all current watches and warnings on a tropical or
subtropical
cyclone. It also gives the cyclone position in terms of latitude and longitude coordinates and distance from a selected land point or island, as well as the current motion. The advisory
includes the maximum sustained winds in miles per hour and the estimated or measured minimum central pressure in millibars and inches. The advisory may also include information on potential
storm
tides, rainfall or tornadoes associated with the cyclone, as well as any pertinent weather observations.
Public advisories are issued for all Atlantic and Eastern Pacific tropical or subtropical cyclones.
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).
Intermediate public advisories may be issued every 3 hours when coastal watches or warnings are in effect. Additionally, special public advisories may be issued at any time due to significant changes in warnings or in the cyclone.
The numbers 1-5 in the headers are assigned on a rotating basis by cyclone number, i.e., advisories on the first, sixth, or eleventh cyclones of the Atlantic season would be sent under the
WMO header
WTNT31 KNHC; advisories on the second, seventh, or twelfth cyclones of the Atlantic season would be sent under the
WMO header WTNT32 KNHC, and so on.
For a current listing of active storms, please visit our
home page. The most current Tropical Cyclone Public Advisories are found on our
Atlantic
Products and
Eastern Pacific Products pages.
See Example
Tropical Cyclone Forecast/Advisory (TCM) - How To Read
World Meteorological Organization (WMO) and AWIPS (in parenthesis) headers:
WTNT21-25 KNHC (MIATCMAT1-5) – Atlantic
WTPZ21-25 KNHC (MIATCMEP1-5) – E. Pacific
The
Tropical Cyclone Forecast/Advisory contains a list of all current watches and warnings on a tropical or
subtropical
cyclone, as well as the current latitude and longitude coordinates, intensity, and system motion. The advisory contains forecasts of the cyclone positions, intensities, and wind fields
for 12, 24, 36, 48, and 72 hours from the current synoptic time. The advisory may also include information on any pertinent
storm tides associated
with the cyclone. All wind speeds in the forecast advisory in given in knots (nautical miles per hour).
Forecast/Advisories are issued on all Atlantic and
eastern Pacific tropical and subtropical cyclones every six hours at 0300, 0900, 1500, and
2100 UTC
(learn about UTC time). Special Forecast/Advisories may be issued at any time due to significant changes in warnings or in the cyclone.
The numbers 1-5 in the headers are assigned by cyclone number, i.e., advisories on the first, sixth, or eleventh cyclones of the Atlantic season would be sent under the
WMO header
WTNT21 KNHC; advisories on the second, seventh, or twelfth cyclones of the Atlantic season would be sent under the
WMO header WTNT22 KNHC, and so on.
For a current listing of active storms, please visit our
home page. The most current Tropical Cyclone Forecast/Advisories are found on our
Atlantic
Products and
Eastern Pacific Products pages
See Example
Tropical Cyclone Discussion (TCD)
World Meteorological Organization (WMO) and AWIPS (in parenthesis) headers:
WTNT41-45 KNHC (MIATCDAT1-5) – Atlantic
WTPZ41-45 KNHC (MIATCDEP1-5) – E. Pacific
The
Tropical Cyclone Discussion explains the reasoning for the analysis and forecast of a tropical or
subtropical
cyclone. It includes a table of the forecast track and intensity.
Tropical Cyclone Discussions are issued on all Atlantic and
eastern Pacific tropical and subtropical cyclones every six hours. Special tropical
cyclone discussions may be issued at any time due to significant changes in warnings or in the cyclone.
Tropical Cyclone Discussions 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).
Tropical Cyclone Discussions 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).
The numbers 1-5 in the headers are assigned by cyclone number, i.e., discussions on the first, sixth, or eleventh cyclones of the Atlantic season would be sent under the
WMO header
WTNT41 KNHC; discussions on the second, seventh, or twelfth cyclones of the Atlantic season would be sent under the
WMO header WTNT42 KNHC, and so on.
For a current listing of active storms, please visit our
home page. The most current Tropical Cyclone Discussions are found on our
Atlantic
Products and
Eastern Pacific Products pages
See Example
Tropical Cyclone Surface Wind Speed Probabilities (PWS)
World Meteorological Organization (WMO) and AWIPS (in parenthesis) headers:
FONT11-15 KNHC (MIAPWSAT1-5) – Atlantic
FOPZ11-15 KNHC (MIAPWSEP1-5) – Eastern Pacific
FOPA11-15 PHFO (HNLPWSCP1-5) – Central Pacific (issued by CPHC)
The
Tropical Cyclone Surface Wind Speed Probabilities text product provides probabilities, in percent, of sustained wind speeds equal to
or exceeding 34-, 50-, and 64-knot wind speed thresholds. These wind speed probabilities are based on the track, intensity, and wind structure forecasts and uncertainties from the
National
Hurricane Center and the
Central Pacific Hurricane Center and are computed for coastal and inland cities as well as offshore locations
(e.g., buoys).
These text products are issued on all Atlantic and
eastern Pacific tropical and subtropical cyclones every six hours at 0300, 0900, 1500, and
2100 UTC
(learn about UTC time). Special tropical cyclone surface wind speed probabilities may be issued at any time due to significant changes in
warnings or in the cyclone.
The numbers 1-5 in the header are assigned on a rotating basis by cyclone number, i.e., probabilities on the first, sixth, or eleventh cyclones of the Atlantic season would be sent under
the WMO header FONT11 KNHC; probabilities on the second, seventh, or twelfth cyclones of the Atlantic season would be sent under the WMO header FONT12 KNHC, and so on.
Three types of tropical cyclone wind speed probability values will be created during 2006. Not all of these values will be distributed or placed on the Internet. For each probability value,
the event in question is a sustained (one-minute average) surface (10 m) wind speed of at least a particular threshold value (34, 50, or 64 kt) at a specific location.
Cumulative – These values tell you the overall probability the event will occur sometime during the specified cumulative forecast period (0-6 hours, 0-12, 0-18, etc.) at each
specific point. These values are provided in both the text and graphical formats. In the
text product, the numbers are in parentheses. The
graphical
products depict only cumulative values. The text product is transmitted to users via normal NWS dissemination methods. The graphic is available on the internet from the
National
Hurricane Center and the
Central Pacific Hurricane Center.
Individual – These values tell you the probability the event will start sometime during the specified individual forecast period (0 - 6 hours, 6-12, 12-18, etc.) at each specific
point. These periods are individual, since nothing that occurs before or after the specified period affects the probability. These values are provided only in the text NHC product. They are
the values outside of the parentheses (cumulative values are in the parentheses). The term "individual" also makes a clear distinction from the cumulative period values for users.
Incremental – These values tell you the probability the event will occur sometime during the specified forecast period (0 - 6 hours, 6-12, 12-18, etc.) at each specific point.
These values are incremental since they can increase in value by accounting for the possibility the event might start in an earlier period and still be occurring in the specified period.
For a current listing of active storms, please visit our
home page. The most current Tropical Cyclone Surface Wind Speed Probabilities are found on our
Atlantic
Products and
Eastern Pacific Products pages
See Example
Note:
View a more detailed description of the wind speed probabilities products.
Tropical Cyclone Update (TCU)
World Meteorological Organization (WMO) and AWIPS (in parenthesis) headers:
WTNT61-65 KNHC (MIATCUAT1-5) – Atlantic
WTPZ61-65 KNHC (MIATCUEP1-5) – E. Pacific
The TCU is a brief alphanumeric text product containing either block paragraph text, a formatted storm summary section, or both. TCUs are issued to inform users of significant changes in a
tropical cyclone in between regularly scheduled public advisories. Such uses include, but are not limited to the following:
- To provide timely information of an unusual nature, such as the time and location of landfall, or to announce an expected change in intensity that results in an upgrade or downgrade of status (e.g., from a tropical storm to a hurricane).
- To provide a continuous flow of information regarding the center location of a tropical cyclone when watches or warnings are in effect and the center can be easily tracked with land-based radar.
- To provide advance notice that significant changes to storm information will be conveyed shortly, either through a subsequent TCU or through a Special Advisory.
- To announce changes to international watches or warnings made by other countries, or to cancel U.S. watches or warnings.
- To issue a U.S. watch or warning, but only if the TCU precedes a special advisory that will contain the same watch/warning information, and indicates the special advisory will be issued shortly.
The storm summary section is identical in format to the storm summary section found in the TCP. The storm summary section is required whenever the TCU is issued to update storm intensity, location, or motion information. The storm summary section is not required for TCUs issued to provide advance notice that significant changes to storm information will be conveyed shortly, or for those issued to convey changes to watches or warnings.
For a current listing of active storms, please visit our
home page. The most current Tropical Cyclone Updates are found on our
Atlantic
Products and
Eastern Pacific Products pages
See Example
Tropical Cyclone Position Estimate (TCE)
The Tropical Cyclone Position Estimate (TCE) has been discontinued effective with the 2013 hurricane season. The relevant information can be found in the
Tropical Cyclone Update (TCU).
Tropical Weather Outlook (TWO)
World Meteorological Organization (WMO) and AWIPS (in parenthesis) headers:
ABNT20 KNHC (MIATWOAT) – Atlantic
ABPZ20 KNHC (MIATWOEP) – E. Pacific
The Tropical Weather Outlook discusses significant areas of disturbed weather and their potential for development during the next 5 days, including a categorical forecast of the probability of tropical cyclone formation during the first 48 hours, and during the entire 5-day forecast period. The 48 h and 5-day probabilities of formation for each disturbance are given to the nearest 10% and expressed in terms of one of the following categories: low probability of development (0-30%), medium probability (40-60%), and high probability of development (70-100%).
The Tropical Weather Outlook is issued every six hours from 15 May–30 November. Local issuance times are shown in the table below.
| Basin |
Local Issuance Times During Daylight Savings Time |
Local Issuance Times During Standard Time |
Atlantic
(15 May–30 November |
2:00 am EDT
8:00 am EDT
2:00 pm EDT
8:00 pm EDT |
1:00 am EST
7:00 am EST
1:00 pm EST
7:00 pm EST |
Eastern North Pacific
(15 May–30 November) |
5:00 am PDT
11:00 am PDT
5:00 pm PDT
11:00 pm PDT |
4:00 am PST
10:00 am PST
4:00 pm PST
10:00 pm PST |
A Special Tropical Weather Outlook is issued when there have been important changes with areas of disturbed weather over tropical or subtropical waters that need to be conveyed before the next scheduled release of the Tropical Weather Outlook. The Special Tropical Weather Outlook can be used to report the findings of reconnaissance aircraft missions, and can also be used for disturbances outside of the normal hurricane season when Tropical Weather Outlooks are not routinely issued. The disturbance being updated in the Special Tropical Weather Outlook will be highlighted at the top of the product, and other systems discussed in previous Tropical Weather outlooks will also be included.
Please note the (Special) Tropical Weather Outlook has a companion
Graphical Tropical Weather Outlook that will be updated at the same time.
For a current listing of active storms, please visit our
home page. The most current Tropical Weather Outlook is found on our
Atlantic
Products and
Eastern Pacific Products pages.
See Example
Tropical Cyclone ICAO (Aviation) Advisory (TCA)
World Meteorological Organization (WMO) and AWIPS (in parenthesis) headers:
FKNT21-25 KNHC (MIATCANT1-5) – Atlantic
FKPZ21-25 KNHC (MIATCAPZ1-5) – E. Pacific
The Aviation Tropical Cyclone Advisory is issued to provide short term tropical cyclone forecast guidance for
international aviation safety and routing purposes. The TCA lists the current TC position, motion, and
intensity, and includes 6, 12, 18, and 24 hour forecast positions and intensities. Position and intensity information
for forecast hours (+06, +12, +18 and +24) is derived from interpolated forecast information – intensity is
rounded to the nearest 5 knots.
Issuance of the Aviation Tropical Cyclone Advisory occurs every six hours at the regular advisory issuance time of 0300,
0900, 1500, and 2100 UTC
(learn about UTC time). For 2008, the bulletin's information is valid at
the routine advisory times (0300, 0900, 1500 and 2100 UTC) and is not anchored to the synoptic times. TCAs for
special advisories will be issued for the same circumstances that apply for a standard advisory.
See Example
Monthly Tropical Weather Summary
World Meteorological Organization (WMO) and AWIPS (in parenthesis) headers:
ABNT30 KNHC (MIATWSAT) – Atlantic
ABPZ30 KNHC (MIATWSEP) – E. Pacific
The Monthly Tropical Weather Summary is issued on the first day of every month during the
hurricane season. It briefly describes the previous
month's
tropical cyclone actvity and gives a table of basic meteorological statistics, such as the dates of occurrence and estimated peak
intensity, for all of the season's tropical cyclones to date. Narrative summaries for individual cyclones are no longer included as of 2009, although brief descriptions for records of interest
may be provided.
Users requiring comprehensive information on each tropical cyclone including synoptic history, meteorological statistics, casualties and damages, and the post-analysis best track (six-hourly positions and intensities), are encouraged to consult the end of season tropical cyclone reports. Atlantic and East Pacific tropical cyclone reports are available at
www.nhc.noaa.gov/data/tcr/.
Atlantic Tropical Weather Summaries are issued under
WMO and AWIPS header ABNT30 KNHC and MIATWSAT.
Eastern Pacific Tropical
Weather Summaries are issued under
WMO header ABPZ30 KNHC and AWIPS header MIATWSEP.
The most current Monthly Tropical Weather Summary is found on our
Atlantic Products and
Eastern Pacific Products pages.
See Example
