Media Center
Climate Bulletin for Sri Lanka (Week of 13 October – 20 October 2023)
Highlights
Rainfall Prediction: Heavy rainfall (≥ 105 mm) is predicted for the Southern, Sabaragamuwa, Western, Uva, Central, Eastern, North Western, North Central provinces and fairly heavy rainfall (75 mm) is predicted for the Northern province during 12 – 18 Oct.
Monitored Rainfall: During the last week, average daily rainfall over Sri Lanka was 14.5 mm and hydro catchment area received 22.3 mm. Extreme rainfall was recorded in southern coast while flash floods were experienced in Akurana on 8 Oct.
Monitored and Predicted Wind: During 13 – 19 Oct, up to 4 m/s of north westerly winds are expected at 850 mb (1.5 km).
Monitored Sea and Land Temperature: Sea surface temperature around Sri Lanka was 0.25 – 1.0ºC above normal. From 4 – 11 Oct, maximum daily temperature was recorded in Polonnaruwa (36.8ºC) and Vavuniya (36.2ºC).
Interpretation
Monitoring
Rainfall: During the last two weeks, there had been very heavy rainfall over the following areas:
Galle, Nuwara Eliya.
Daily Average Rainfall in the Met stations for previous week of (4 th October – 11 th October) = 14.5 mm
Maximum Daily Rainfall: 92.1 mm. Minimum Daily Rainfall: 0.0 mm.
Wind: West-southwesterly winds prevailed in the sea area and around the island last week.
Temperatures: The temperature anomalies were below normal for some parts of the Western province of the country driven by the warm SST’s.
Prediction
Rainfall: During the next week (12 th October – 18 th October), heavy rainfall (≥ 105 mm) is predicted for the Southern, Sabaragamuwa, Western, Uva, Central, Eastern, North Western, and North Central provinces and fairly heavy rainfall (75 mm) is predicted for the Northern province of the country.
Temperatures: The temperature will remain seasonably near normal during 13 th – 19 th October.
Teleconnections: A positive Dipole Mode has set in across the Indian Ocean since 8 th of June. MJO shall slightly enhance the rainfall during 12 th – 16 th October, moderately enhance the rainfall during 17 th – 21 st October, and significantly enhance the rainfall during 22 nd – 26 th October.
Seasonal Precipitation: The precipitation forecast for the October-November-December, 2023 season shows a 50 – 60% tendency toward above normal precipitation.
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 |
