Tropical Cyclone Severity Scale
Adequately reflecting the severity of tropical cyclones using the new Tropical Cyclone Severity Scale.
Abstract: For decades, meteorologists and governments have been warning communities in coastal areas for an imminent tropical cyclone (TC) using the Saffir-Simpson Hurricane Wind Scale (SSHWS). The SSHWS categorizes a TC based on its maximum wind speeds, and is used in defining evacuation strategies and humanitarian response. However, the SSHWS considers only wind hazard, whereas a TC can also cause severe conditions through its high storm surges and extreme rainfall, triggering coastal and inland flooding. Consequently, the SSHWS fails to mirror the TC’s total severity. This becomes evident when looking at past events such as Hurricane Harvey (2017), which was classified as a Tropical Storm while it caused widespread flooding in the Houston (TX) area, with precipitation totals exceeding 1.5 m. With the absence of storm surge and rainfall, adequate risk communication with the SSHWS can be challenging, as the public can (mistakenly) perceive a low-category TC as a low-risk TC. To overcome this, we propose the new Tropical Cyclone Severity Scale (TCSS) that includes all three major TC hazards in its classification. The new scale preserves the categorization as used in the SSHWS, to maintain familiarity amongst the general public. In addition, to support communication about the most extreme TCs, we extend the TCSS with a Category 6. While the SSHWS is currently used to communicate about the total event severity, the TCSS is primarily designed to be applied on a local-scale, hereby supporting local-scale risk communication efforts and evacuation strategies prior to a TC landfall.
[revise & resubmit]