As hurricane season continues across South Alabama, the National Weather Service Southern Region has consolidated its storm-tracking tools into a single online destination designed to help residents prepare for and respond to tropical weather. The tropical web portal brings together storm outlooks, active storm information, threat and impact graphics, satellite and radar imagery, and preparedness resources in one place, giving Gulf Coast residents a one-stop shop during hurricane season.
Tracking Storm Surge and Coastal Flooding
One of the portal’s key features displays storm surge and coastal flood hazards, along with potential inundation levels, using data from the National Hurricane Center and National Weather Service GIS services. The map shows hazard categories ranging from coastal flood statements and advisories to full watches and warnings, as well as storm surge watches and warnings specific to tropical systems.
Potential inundation is depicted in bands showing water levels greater than 1 foot, 3 feet, 6 feet and 9 feet above ground, giving residents a visual sense of how high floodwaters could rise in a given area. A storm surge watch means life-threatening inundation from a tropical cyclone is possible, generally within 48 hours, while a storm surge warning means that danger is expected generally within 36 hours. Coastal flood watches and warnings are used instead in Southern California, where storm surge products don’t apply.
Rainfall, Storms and Fire Weather
Beyond tropical systems, the portal offers rainfall forecasts, excessive rainfall outlooks and thunderstorm outlooks covering the next seven days, drawing on data from the Weather Prediction Center and the Storm Prediction Center. Fire weather outlooks for the next five days are also included, courtesy of the Storm Prediction Center. Rounding out the hydrology tools are national river observations and forecasts, tide and current predictions, and a NOAA inundation dashboard, all useful for residents monitoring flooding risk from multiple angles at once.
Understanding the Hurricane Threats and Impacts Graphics
A central feature of the portal is its Hurricane Threats and Impacts, or HTI, graphics. These color-coded maps are issued by local Weather Forecast Offices whenever tropical cyclone wind, or storm surge, watches and warnings are in effect for part of their coverage area. The graphics are updated with each new National Hurricane Center or Central Pacific Hurricane Center forecast and remain active until the threat has passed locally.
Unlike the familiar hurricane “cone” graphic, which shows only the most likely track of a storm’s center, the HTI graphics show the geographic extent of hazards such as wind, storm surge, flooding rain and tornadoes, along with their severity and potential impacts. Because impacts often extend well beyond the cone itself, forecasters designed the HTI system to build in a safety margin that accounts for forecast error, not just the most likely outcome.
The color scale used in the graphics runs from warm to hot colors as threat levels increase. On the wind graphic, for example, areas shaded purple should be ready for winds exceeding 110 mph, consistent with at least a Category 3 hurricane, while areas shaded red face hurricane-force winds between 74 and 110 mph, consistent with a Category 1 or 2 storm. Similar color scales apply to the other hazards tracked by the system.
How to Use the Portal During a Storm
The HTI graphics can be accessed through the National Weather Service Southern Region tropical portal, and most coastal Weather Forecast Office websites link directly to the relevant regional page during active storms. Once on the portal, users can click the “Threats and Impacts” tab, which displays wind hazards by default, then use radio buttons to switch between other hazards such as storm surge or flooding rain.
Clicking a specific location on the map brings up detailed, location-specific forecast information, including what hazard to expect, where, when, how much and how long, drawn from local text products. Clicking also produces a written description of potential impacts, often developed with input from local emergency managers, giving residents a clearer sense of what to actually prepare for rather than just a raw forecast number.
Officials caution that the map is not simply a forecast, but a depiction of the forecast with a safety margin built in to account for uncertainty. That means the map may not always match text-based forecast information exactly, since the text reflects the most likely outcome while the map reflects a reasonable worst-case scenario. The same threat-level information is also available through the National Digital Forecast Database for users who prefer that format.
Additional Resources
The portal also provides satellite imagery covering the tropical Atlantic, Gulf of Mexico, Caribbean, U.S. Atlantic coast, Puerto Rico and Pacific sectors, in visible, infrared and water vapor formats, along with scatterometer and altimeter data and foreign radar composites for the Caribbean, Central America and Mexico. Preparedness brochures and videos are available in both English and Spanish, along with the current lists of Atlantic and Pacific basin storm names for the season.
The National Weather Service Southern Region Headquarters, which oversees the portal, is based at 819 Taylor Street in Fort Worth, Texas. As always, officials urge residents along the Gulf Coast to follow the guidance of local emergency management officials during any active storm, using the portal as one tool among several to stay informed.