Media Center
Climate Bulletin for Sri Lanka (Week of 20 October – 27 October 2023)
Highlights
Rainfall Prediction: Heavy rainfall (≥ 115 mm) is predicted for the Southern, Sabaragamuwa, Western, Uva, Central, Eastern, North Western provinces during 19 – 25 Oct. Fairly heavy rainfall (≥ 75 mm) is predicted for the North Central and Northern provinces during 19 – 25 Oct.
Monitored Rainfall: During the last week, average daily rainfall over Sri Lanka was 17.1 mm and hydro catchment area received 19.6 mm. Extreme rainfall was recorded in Southern coast and extreme rainfall is predicted for Southern coast and districts.
Monitored and Predicted Wind: From 10 – 16 Oct, up to 4 m/s of south westerly winds were at 850 mb (1.5 km). During 20 – 26 Oct, up to 3 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 1.0 – 1.5ºC above normal. From 11 – 18 Oct, maximum daily temperature was recorded in Anuradhapura (34.5ºC) and Polonnaruwa (34.3ºC).
Interpretation
Monitoring
Rainfall: During the last two weeks, there had been very heavy rainfall over the following area: Anuradhapura
Daily Average Rainfall in the Met stations for previous week of (11th October – 18th October) = 17.1 mm
Maximum Daily Rainfall: 92.4 mm & Minimum Daily Rainfall: 0.0 mm.
Wind: South westerly winds prevailed in the sea area and around the island last week..
Temperatures: The temperature anomalies were above normal for some parts of the Sabaragamuwa and Central provinces of the country driven by the warm SST’s.
Prediction
Rainfall: During the next week (19th October – 25th October), heavy rainfall (≥ 115 mm) is predicted for the Southern, Sabaragamuwa, Western, Uva, Central, Eastern, and North Western provinces and fairly heavy rainfall (≥ 75 mm) is predicted for the Northern and North Central provinces.
Temperatures: The temperature will remain above normal for some parts of the Northern and Eastern provinces during 20th – 26th October.
Teleconnections: A positive Dipole Mode has set in across the Indian Ocean since 8th of June.
MJO shall slightly enhance the rainfall during 19th – 28th October and near neutral the rainfall during 29th October – 2nd November for Sri Lanka.
Seasonal Precipitation: The precipitation forecast for the November-December-January, 2024 season shows a 40 – 45% 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 |
