Weather Summary of Macao ( July 2009 )

This month was cooler and drier than normal. The monthly mean air temperature, monthly mean minimum air temperature and monthly mean maximum air temperature were 28.1, 25.6 and 31.3 degree Celsius respectively, 0.5, 0.7 and 0.2 degree Celsius lower than the normals respectively. The monthly mean minimum air temperature was also the lowest of July since 2001. The monthly minimum air temperature was 22.3 degree Celsius and the second lowest of July in the record, just higher than 22.1 degree Celsius recorded on 15th July 1961. The monthly mean relative humidity was 72%, 10.2% lower than the normal. The monthly minimum relative humidity was 35%. Both were the lowest values of July in the record. The total insolation was 238 hours, 11.8 hours more than the normal. The monthly total evaporation was 75.8 mm, 17.1 mm less than the normal. The monthly precipitation and accumulated precipitation since January were 229.4 mm and 1125.6 mm respectively, 70.6 mm and 267.3 mm less than the normals respectively. Six Thunderstorm Warnings and one Rainstorm Warning were issued during this month. Furthermore, the Tropical Cyclones Signals were hoisted from 22:00 on day 10 to 07:00 on day 12 as well as 23:00 on day 17 to 12:30 on day 19 respectively because of the approaching of Tropical Storm "Soudelor" and Typhoon "Molave". The Region was under the influence of a southerly airstream on day 1 and was under the influence of a southwesterly airstream on day 2 and day 3. Meanwhile, it was cloudy with sunny periods and also with some isolated showers in the morning of day 3. On day 4 and day 5, a trough of low pressure made the local weather to be mainly cloudy with thundery showers. Furthermore, the Rainstorm Warning was issued from 22:05 to 23:10 on day 4 because of the heavy showers. The monthly minimum air temperature, 22.3 degree Celsius, was also recorded on day 4. Lightning also occurred on day 5. It was cloudy with sunny periods, isolated showers and lightning under the influence of a southerly airstream on day 6. A ridge of high pressure brought the hot and mainly fine weather to the Region in the following two days. Since day 9, it became fine, dry and very hot under the influence of the hot airmass. The Tropical Cyclone Signal No. 1 was hoisted at 22:00 on day 10 due to the approaching of a tropical depression. On day 11, the tropical depression intensified into a tropical storm and was named "Soudelor". It crossed the northern part of South China Sea. The local weather was very hot and fine, apart from cloudy periods and occasional showers. As "Soudelor" was further approaching to Macao, the Signal No. 3 was hoisted at 19:00. On day 12, as "Soudelor" was weakening and departing from Macao as well as a ridge of high pressure came into effect, all signals were lowered at 07:00. It was mainly fine with some showers in the early morning. On day 13, it remained mainly fine. On day 14, it was hot and cloudy with sunny periods. On day 15, a ridge of high pressure and a low pressure area over South China Sea affected the local weather together. It was very hot and cloudy with sunny periods and some thundery showers in the morning. From day 16 to the beginning of day 18, it was very hot and fine apart from cloudy periods and isolated showers under the influence of a ridge of high pressure. The monthly maximum air temperature, 36.2 degree Celsius, was recorded on day 18. On the other hand, a tropical depression was intensifying and approaching to the Region. It intensified into a tropical storm on day 16 and was named "Molave". It further intensified into a severe tropical storm on day 17. The Tropical Cyclone Signal No. 1 was hoisted at 23:00 on the same day. On day 18, "Molave" intensified into a typhoon. As "Molave" approached to Macao towards the end of the day, Signal No. 3 substituted Signal No. 1 at 18:30. The local weather became showery with thunderstorms and lightning. On day 19, all signals were lowered at 12:30 because of the weakening and departure of "Molave". It was cloudy with showers, heavy at times in the beginning of the day. The monthly highest daily precipitation, 68.6mm, was recorded on that day. On day 20, it was cloudy with sunny periods and occasional showers under the influence of a southerly airstream. In the following three days, a ridge of high pressure made the local weather to be fine, apart from cloudy periods and isolated showers. The Region became to be affected by a southwesterly airstream since day 24. It was cloudy with sunny periods and isolated showers. Furthermore, lightning also occurred on day 26. It was cloudy with sunny periods and showers, thundery at times on day 28. The local weather was under the influence of a southerly airstream on day 29 and under the influence of a maritime airstream on day 30 and day 31. It was cloudy with sunny intervals and isolated showers. Some meteorological elements and their deviation from the 30-year mean ( 1971 - 2000 ) * Please find the attachment.