The Macao Meteorological and Geophysical Bureau (SMG) says that a variety of factors are considered when deciding whether to issue a rainstorm warning. The bureau hopes public will understand that weather forecasting is not a precise science.
On Friday, the SMG held a press conference to introduce the city’s newest rainstorm alarm signals. In June, the local government publicized an administrative regulation announcing the new system, which consists of three tiers.
During his explanation, SMG director Leong Weng Kun remarked that the department does not issue a rainstorm signal solely based on the weather. Consideration for the public is also taken into account.
Previously, the public has complained about the SMG’s unsatisfactory rainstorm warnings, especially concerning those issued during school days, when students and parents can become confused about school scheduling arrangements.
In some cases, the SMG issues a rainstorm signal in the morning, only slightly before school begins, suggesting the suspension of classes for that day. The local community has complained about the ensuing chaos and confusion.
On Friday, Leong explained that the SMG issues rainstorm warnings after considering the weather’s impact on society and the residents. He hopes that the public can understand that, in some cases, in view of said impact, the SMG issues a serious signal in order to reduce the effect, despite the fact that these warnings may turn out to be exaggerated.
“[With] weather forecasts, it is difficult to be 100% accurate,” said Leong, who added that there are certain to be inaccuracies involved some of the time.
The new rainstorm standards will come into effect on September 1, 2020.
The first level is the yellow rainstorm warning signal, meaning that heavy rain has fallen or is expected to fall generally over Macau, exceeding 20 millimeters in an hour and is likely to continue.
The second level is the red rainstorm warning signal, indicating heavy rain has fallen or is expected to fall generally over Macau, exceeding 50 millimeters in an hour and is likely to continue.
The last level is the black rainstorm warning signal. Whenever this signal is hoisted, it means heavy rain has already fallen or is expected to fall generally over Macau, exceeding 80 millimeters in an hour.
According to the SMG, by classifying rainstorms recorded between 2015 and 2019 with the new standards, there would have been 148 yellow signals (29.6 times per year), 12 red signals (2.4 per year), and one black signal (0.2 times per year). Over 75% of heavy rainstorms lasted less than 80 minutes.
On average, nine yellow signals occurred annually between 6 a.m. and 9 a.m. During the same period, an average of 0.8 red signals were hoisted and no black signals were raised.
The SMG said it is unable to predict whether the new standards will lead to more or fewer school suspensions.
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