## 4 CP Warning Effect Verification in Another Two Similar Accidents  
To confirm the findings in Section 3, another two cruise-boat capsizing accidents, also possibly due to the strong convective wind gusts, were investigated; however, ship-based AIS data were unavailable. In both cases, it was confirmed that in the ECMWF product, the nearest wind speeds at the shipw locations were both less than 8 m/s (force 5 wind on the Beaufort Scale), far from the actual situation. In local time 1440 Z (UTC 0640Z), on 4 June 2016, a small cruise boat (only 13 tonnage), the \"Double Dragon\", capsized in the middle of a resort lake upstream of the Yangtze River during a sudden convective rainstorm. The nearby meteorological station observed that before and after the incident, the local area was heavily affected by a multicell convective storm cluster weather system moving from northwest to southeast, combined with other severe convective disastrous weather and the impact of complex terrain, resulting in a strong local character of short-term gusty winds. The wind speed rapidly increases over a short period of time, with a maximum instantaneous wind speed of 33.5 m/s (force 12 wind on the Beaufort Scale). According to meteorological data, lightning, short-term heavy rainfall, and sudden temperature drops occurred in the vicinity of Bailong Lake at the time of the incident, all of which are typical characteristics of strong convective events [26]. In the \"Double Dragon\" cruise boat accident, similar to the discussion in Section 3, the CP variable predicted at a 24 h lead time shows great potential to become an early-warning factor in the ECMWF deterministic forecast (Figure 8a) and ensemble forecast (Figure 8b,c), i.e., the horizontal and temporal distribution of the maximum CP value is observed to be very close the value at the time of the accident. In contrast, the LSP value is almost negligible before and after the accident. On 5 July 2018 at 17:45 local time (UTC 1045Z), the \"Phoenix\" and \"Princess Aisha\" cruise ships carrying 101 and 42 people, respectively, capsized and sank in a severe storm near Phuket Island in southern Thailand. Due to proper rescue efforts, all the tourists on the \"Princess Aisha\" cruise ship were rescued, but 47 Chinese tourists on the \"Phoenix\" unfortunately died. In this accident, the 24 h lead CP prediction (Figure 9) also showed a corresponding sudden increase at the moment. However, whether this trend can be applied as an early warning factor is open to question. The main reason is due to the fact that convection is the common tropical weather type, and the accident was during the rainy season, which is when cumulus rain is almost routine. It can be seen that the CP value on the day of the accident was greater than the previous day but less than the next (Figure 9). In addition, numerical weather simulation usually applies different cumulus physics and parameterization schemes in the tropics from those in the extratropical region. Moreover, the \"Phoenix\" boat's design and operation was both found to be partially unqualified and led to the disaster [27]. Therefore, the warning factor discovery in other regions cannot be directly transplanted into a tropical area, as the applicable warning factor in the tropics for short-term high wind needs further study. Given the ECMWF deterministic product grid resolution (0.5 \(\times\) 0.5 degree), we could suggest that a sudden predicted CP increment of over 20 mm from nearly zero should be taken with caution but still seriously under the background of a negligible LSP value. Since this article is focused on studying strong wind gust warning potential through an indirect method, there are many questions that remain unsolved. For example, when the magnitude of the CP changes significantly, does it necessarily indicate that short-term high winds will occur at a specific time, or will they occur sometime before or after, that is, the exact time of the short-term high winds occurrence is not analyzed.