Graphical Tropical Weather Outlook
Updated 3 March 2009
- Changes for 2009
- Explanation of the Graphical TWO
- Probabilistic Genesis Forecasts
- Potential Benefits of a Graphical TWO
3. Explanation of the Graphical TWO
The NHC issues a text-based TWO four times daily that discusses areas of disturbed weather in the tropics and provides
an assessment of the potential for these features to develop into tropical cyclones (TCs). The GTWO is a web-based graphic
that supplements the TWO by showing the most recently-available geostationary satellite imagery and encircling disturbances
of interest in that image. Each disturbance is numbered, with text descriptions of each system provided beneath the graphic.
Active TCs are also indicated on the graphic in the form of a cyclone symbol (i.e., an "L" for tropical depressions, a
tropical storm symbol or a hurricane symbol). Text descriptions for the disturbances and active cyclones also appear in a
pop-up window whenever a user moves the mouse pointer over the system.
During the 2007 and 2008 hurricane seasons, NHC issued the GTWO on en experimental basis. As part of the experimental
product process, the GTWO was tested and evaluated during those hurricane seasons. This assessment included the routine
issuance of the product, internally testing possible enhancements to the product, and gathering user input via an online survey.
This document provides a description of the results of the experimental phase, along with the description of the GTWO that will
become operational at the start of the 2009 hurricane season.
Next: Probabilistic Genesis Forecasts