HIGH SEAS FORECASTS
The TAFB issues High Seas Forecast for the tropical and subtropical Atlantic, eastern Pacific, and south Pacific Oceans. These products are now-casts through 36 hr forecasts of winds, waves, and convection updated every six hours. The products include marine warnings for gale, storm, and tropical cyclone conditions. The products can also include information on reduced visibility and icing hazards.
The TAFB has three areas of responsibility (8.5K GIF): The Atlantic Ocean from 3N to 32N west of 35W, including the Caribbean Sea and Gulf of Mexico; the Northeast Pacific Ocean from the Equator to 30N east of 140W; and the Southeast Pacific Ocean from the Equator to 18.5S east of 120W.
The most current High Seas Forecasts are found on the Forecast Products page. Products are transmitted under a variety of World Meteorological Organization (WMO) and AFOS headers:
Primary: Alternate: WMO AFOS WMO AFOS Atlantic Forecast: FZNT02 MIAHSFAT2 FZNT01 NFDHSFAT1 KNHC KWBC Northeast Pacific Forecast: FZPN03 MIAHSFEP2 FZPN01 NFDHSFEP1 KNHC KWBC Southeast Pacific Forecast: FZPN04 MIAHSFEP3 KNHC
Alternate headers for the Atlantic and Northeast Pacific Forecasts are where TAFB forecasts are appended to High Seas Forecasts of the Marine Prediction Center. In addition, all high seas products are transmitted by radiofax.
OFFSHORE WATERS FORECASTS
The TAFB issues Offshore Waters Forecasts for the southwest north Atlantic, Caribbean Sea, and Gulf of Mexico. These products are now-casts through 36 hr forecasts of winds, waves, and convection updated every six hours. The products include marine warnings for gale, storm, and tropical cyclone conditions. The products can also include information on reduced visibility and other marine hazards.
The TAFB has three areas of responsibility: The Atlantic Ocean south of 31°N west of 65°W; the entire Caribbean Sea and the Gulf of Mexico beyond the Coastal Waters Forecast.
The most current Offshore Waters Forecasts are found on the Forecast Products page. Products are transmitted under a variety of World Meteorological Organization (WMO) and AWIPS headers:
WMO AWIPS SW North Atlantic FZNT23 KNHC MIAOFFNT3 and Caribbean Forecast Gulf of Mexico Forecast FZNT24 KNHC MIAOFFNT4
SATELLITE RAINFALL ESTIMATES
(Woodley-Griffith technique)
The TAFB provides satellite rainfall estimates for tropical cyclones or other significant convective systems when these systems threaten land. These estimates employ infrared satellite imagery and satellite observed motion estimates. Results are given in ranges of potential rainfall in 1 degree wide semicircles to the left and right of the observed system motion.
The TAFB issues estimates when tropical cyclones or convective systems threaten the Caribbean region or the southeastern United States. They are also issued when eastern Pacific tropical cyclones threaten the west coast of Mexico.
TAFB satellite rainfall estimates are on the Forecast Products page. They are transmitted under the following WMO and AWIPS headers:
WMO: AWIPS: TCCA21 KNHC MIASTDECA TCCA22 KNHC MIASTDCCA TCCA23 KNHC MIASTDWCA
TROPICAL/SUBTROPICAL CYCLONE POSITION AND INTENSITY ESTIMATES
The TAFB provides the National Hurricane Center with position estimates of tropical cyclones every three hours and intensity estimates every six hours. Intensity estimates use the Dvorak technique, which is a statistical system using observed satellite cloud pattern and a set of rules to produce a current estimate of a cyclone's strength. Estimates can be made from both visible and infrared satellite imagery. The Dvorak technique is the main tool for determining tropical cyclone strength when it is out of range of reconnaissance aircraft.
The TAFB also provides NHC with position and intensity estimates for subtropical cyclones (a hybrid between tropical cyclones and frontal or extratropical cyclones) using the Herbert-Poteat technique.
TAFB's position and intensity estimates are not currently available to the public. However, the intensity estimates (called T numbers, CI numbers, and ST numbers), are often referred to in NHC's Tropical Cyclone Discussions and Preliminary Reports. The following table (taken from the reports mentioned below) gives the approximate wind and pressure values for the CI and ST numbers.
CI Sustained Atlantic W Pacific ST Sustained Number winds Min. Pres. Min. Pres. Number winds 1.0 25 kt 1.5 25 kt 1.5 25-30 kt 2.0 30 kt 1009 mb 1000 mb 2.5 35 kt 1005 mb 997 mb 2.5 35-40 kt 3.0 45 kt 1000 mb 991 mb 3.0 45-50 kt 3.5 55 kt 994 mb 984 mb 3.5 55-65 kt 4.0 65 kt 987 mb 976 mb 4.5 77 kt 979 mb 966 mb 5.0 90 kt 970 mb 954 mb 5.5 102 kt 960 mb 941 mb 6.0 115 kt 948 mb 927 mb 6.5 127 kt 935 mb 914 mb 7.0 140 kt 921 mb 898 mb 7.5 155 kt 906 mb 879 mb 8.0 170 kt 890 mb 858 mbNHC uses the Atlantic pressure table for eastern Pacific tropical cyclones. Note that these are intensity estimates and may be superceded by reconnaisance and/or surface observations.
More information on the Dvorak technique is found in NOAA Technical Report NESDIS 11 - Tropical Cyclone Intensity Analysis Using Satellite Data - by Vernon F. Dvorak. More infomation on the Herbert-Poteat technique is found in NOAA Technical Memorandum NWS SR-83 - A Satellite Classification Technique for Subtropical Cyclones - by Paul J. Herbert and K.O. Poteat.
The TAFB is currently testing an objective version of the Dvorak technique used for tropical cyclones with eyes. This could provide intensity estimates every 30 minutes. More information can be obtained from Ray Zehr at the Cooperative Institute for Research in the Atmosphere, Colorado St. University.
GULF OF MEXICO, ATLANTIC AND CARIBBEAN WIND/WAVE NOWCAST/FORECAST
The TAFB produces a graphical marine forecast of wind and waves for selected points in our Gulf of Mexico, Atlantic, and Caribbean forecast area south of 31°N west of 55°W, as well as forecast positions of significant weather systems. It also includes any marine warning areas. The product comes in two varieties: A short term two panel product with a nowcast and a 24 hour forecast (issued four times a day), and a two panel product with 48 and 72 hour forecasts (issued twice a day).
The most current Gulf/Atlantic Wind/Wave Forecasts are found on the TAFB Forecast Products page. They are also transmitted by radiofax.
TROPICAL WEATHER DISCUSSION
This product has changed due to merging with the Satellite Interpretation Message (which has been discontinued). The Atlantic Tropical Weather Discussion (or TWD) is a narrative of significant surface or upper level weather features in the TAFB area of responsiblilty, including fronts, troughs, cyclones, and anticyclones. It includes special feature discussions for systems such as tropical cyclones or tropical disturbances. It also includes satellite-based descriptions of significant weather across the discussion area. The Pacific TWD is similar but less detailed. It concentrates on surface weather systems and satellite-based descriptions of significant weather.
The TAFB issues TWDs for the Atlantic from the Equator to 32N, including the Caribbean and Gulf of Mexico. It also issues them for the northeastern Pacific from the Equator to 32N east of 140W. Both products are issued every six hours.
The most current TWDs are found on the Tropical Cyclone Products page. The Atlantic TWD is transmitted under the WMO header AXNT20 KNHC and the AWIPS header MIATWDAT. The Pacific TWD is transmitted under the WMO header AXPZ20 KNHC and the AWIPS header MIATWDEP.
TROPICAL SURFACE ANALYSIS
The TAFB produces wide-area surface analyses at the 4 synoptic times. Analyses cover the region from 20S to 50N between the Greenwich Meridian westward to 160W. It is a standard surface analysis for synoptic-scale systems with isobars every 4 millibars (2 millibars in the tropics). Analysis and subsections described below are produced on TAFB's Intergraph system.
The most current Tropical Surface Analysis is found on the Tropical Cyclone Products page. It is transmitted graphically under AWIPS header NMCGPHTSA. A subsection of the 0000 UTC analysis is transmitted over the DIFAX circuit. It covers the region from 18S to 40N east of 100W.
ATLANTIC TROPICAL SURFACE ANALYSIS
The Atlantic Tropical Surface Analysis is a subsection of the Tropical Surface Analysis covering the region from 5S to 35N east of 120W. It is transmitted four times a day at 0000, 0600, 1200, and 1800 UTC.
The most current Atlantic Tropical Surface Analysis is found on the TAFB Forecast Product List. It is also transmitted by radiofax.
NORTH AMERICAN SURFACE ANALYSIS
The North American Surface Analysis is a subsection of the Tropical Surface Analysis covering the region from 15N to 50N between 65W and 125W. It is transmitted four times a day at 0000, 0600, 1200 and 1800 UTC.
The most current North American Surface Analysis is found on the Forecast Products page. It is also transmitted by radiofax.
EASTERN PACIFIC WIND/WAVE ANALYSIS
The TAFB produces a graphical marine forecast of wind and waves for selected points in the eastern and south Pacific forecast area from 20°S to 30°N east of 145°W, as well as forecast positions of significant weather systems. It also includes any marine warning areas. The product comes in two varieties: A short term two panel product with a nowcast and a 24 hour forecast (issued four times a day), and a two panel product with 48 and 72 hour forecasts (issued twice a day).
The most current East and South Pacific Wind/Wave Forecasts are found on the Forecast Products page. It is also transmitted by radiofax from Pt. Reyes, California and Honolulu, Hawaii.
