Media Center
Climate Bulletin for Sri Lanka (Week of 08 September – 15 September 2023)
Highlights
Rainfall Prediction: Fairly heavy rainfall (≥ 65 mm) is predicted for the Sabaragamuwa, Southern, Western, Uva, Central provinces and less rainfall is predicted for the rest of the country during 7 – 13 Sep.
Monitored Rainfall: During the last week, average daily rainfall over Sri Lanka was 7.1 mm and hydro catchment areas received 16.3 mm. Highest average rainfall of 23.7 mm/day received Western plains.
Monitored and Predicted Wind: From 29 Aug- 4 Sep, up to 15 m/s of north westerly winds were at 850 mb (1.5 km). During 8 – 14 Sep, up to 15 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 – 1.5oC above normal. From 30 Aug – 6 Sep, maximum daily temperature was recorded in Trincomalee (37.7oC) and Polonnaruwa (36.6oC).
Interpretation
Monitoring
Rainfall: During the last two weeks, there had been heavy rainfall over the following areas: Galle, Kalutara, Colombo, Ratnapura Interpretation
Daily Average Rainfall in the Met stations for previous week of (30th August – 6th September) = 7.1 mm
Maximum Daily Rainfall: 85.1 mm & Minimum Daily Rainfall: 0.0 mm.
Wind: North westerly winds prevailed in the sea area and around the island last week.
Temperatures: The temperature anomalies were near normal for the country driven by the warm SST’s.
Prediction
Rainfall: During the next week (7th September – 13th September), fairly heavy rainfall (≥ 65 mm) is predicted for the Southern, Sabaragamuwa, Western, Uva, and Central 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, Northern, North Central, and Uva provinces and below normal for some parts of the Central province during 8th September – 14th September.
Teleconnections: A positive Dipole Mode has set in across the Indian Ocean since 8th of June. MJO shall slightly enhance the rainfall during the 7th – 16th of September and near neutral the rainfall during the 17th – 21st of 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 |
