HTI is designed to help make preparedness actions more effective. A similar approach is used for depicting each of the remaining hazards. Simply put, locations in purple are being threatened by major hurricane force winds greater than 110 mph (at least Category 3 force), locations in red are being threatened by hurricane force winds between 74-110 mph (Category 1 or 2 force), and so on. Rather, it indicates that these locations should be ready for winds in excess of 110 mph, when taking into account the latest forecast and knowing that (although skilled) the forecast isn't perfect. It is not a mere depiction of forecast conditions to be expected. Example of HTI Graphics for the tropical wind, storm surge, flooding rain, and tornado hazards (left to right) from Hurricane Irma (2017).Įxamining the wind graphic (above left), locations colored in purple have the potential to experience winds greater than 110 mph when accounting for both the forecast and forecast error. The HTI color-scale corresponds to increasing levels of threat and is graduated from warm to hot colors.įigure 1.
Impacts often extend well-beyond the area depicted in the Cone Graphic alone. The HTI graphics, however, show the geographic extent of associated hazards their level of threat and potential impacts. Since the Cone Graphic only reveals the most probable track of the center of the storm, it provides little to no information about projected impacts. Figure 1 (below) offers an example of each hazard-based HTI graphic with the NHC Cone Graphic superimposed (from Hurricane Irma, 2017). Tropical wind, storm surge, flooding rain, and tornadoes are the hazards addressed within the HTI graphics suite. What hazards are described by the HTI Graphics? The HTI graphics account for the latest forecast at specific locations while also including a reasonable safety margin to account for any forecast errors. Through the implicit use of probability data, color-coded HTI graphics depict the potential conditions to protect against with accompanying descriptions of potential impacts needed for effective preparations. Any departure in the forecast from the actual track, size, or intensity of a hurricane can dramatically change its impacts. Once available, they are updated by respective WFOs with each new forecast issued by the National Hurricane Center (NHC) or Central Pacific Hurricane Center (CPHC) and maintained until the threats of these hazards have locally passed.
hurricane or tropical storm) wind watches and warnings, and/or storm surge watches and warnings, are in effect for at least part of their land area of responsibility. HTI graphics are issued by local Weather Forecast Offices (WFOs) when tropical cyclone (i.e. What are the Hurricane Threats and Impacts (HTI) Graphics? Hurricane Threats and Impacts Graphics FAQ Graphics are for areas subject to active tropical cyclone wind and/or storm surge watches and warnings.
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