Media Center
Climate Bulletin for Sri Lanka (Week of 25 August – 01 September 2023)
Highlights
Rainfall Prediction: Light showers (25 mm) are predicted for the Sabaragamuwa, Southern, Northern, Uva provinces during 24 – 30 Aug. Fairly heavy rainfall (≥ 55mm) is predicted for the Sabaragamuwa, Southern, Western, Uva, Central, North Western provinces during 31 Aug – 6 Sep
Monitored Rainfall: During the last week, average daily rainfall over Sri Lanka was ‘light’ (0.9 mm) and hydro catchment areas received ‘light’ (1.2 mm) showers.
Monitored and Predicted Wind: From 15 – 21 Aug, up to 10 m/s of northwest-westerly winds were at 850 mb (1.5 km).During 25 – 31 Aug, up to 10 m/s of northwest-southwesterly winds are expected at 850 mb (1.5 km).
Monitored Sea and Land Temperature: Sea surface temperature around Sri Lanka was 0.5 – 2ºC above normal.From 16 – 23 Aug, maximum daily temperature was recorded in Vavuniya (38.5ºC), Polonnaruwa (38.1ºC) and Pottuvil (37.5ºC).
Interpretation
Monitoring
Rainfall: During the last two weeks, there had been fairly heavy rainfall over the following area: Polonnaruwa.
Daily Average Rainfall in the Met stations for previous week of (16th August – 23rd August) = 0.9 mm. Maximum Daily Rainfall: 29.8 mm & Minimum Daily Rainfall: 0.0 mm.
Wind: Northwest-westerly winds prevailed in the sea area and around the island last week.
Temperatures: The temperature anomalies were above normal for the Western, Sabaragamuwa provinces and some parts of the Southern, Central, Uva, and North Western provinces of the country driven by the warm SST’s.
Prediction
Rainfall: During the next week (24th August – 30th August), light showers (25 mm) are predicted for the Southern, Sabaragamuwa, Northern, and Uva provinces and less rainfall is predicted for the rest of the country.
Temperatures: The temperature will remain above normal for some parts of the Eastern, Uva, Northern, North Central, Southern, and Central provinces during 25th August – 31st August.
Teleconnections:A positive Dipole Mode has set in across the Indian Ocean since 8th of June. MJO shall near neutral the rainfall during 23rd August – 1st September and slightly enhance the rainfall during 2nd – 6th September for Sri Lanka.
Seasonal Precipitation: The precipitation forecast for the September-October-November, 2023 season shows above normal precipitation for the country.
Terminology for Rainfall Ranges
| Rainfall (During 24 hours of the period) | |
| Light Showers | Less than 12.5 mm |
| Light to Moderate | Between 12.5 mm and 25 mm |
| Moderate | Between 25 mm and 50 mm |
| Fairly Heavy | Between 50 mm and 100 mm |
| Heavy | Between 100 mm and 150 mm |
| Very Heavy | More than 150 mm |
