Media Center
Climate Bulletin for Sri Lanka (Week of 19 May – 26 May 2023)
Highlights
Rainfall Prediction: Fairly heavy rainfall is predicted for the Western and Sabaragamuwa provinces and less rainfall is predicted for rest of the country during 18th May – 24th May.
Monitored Rainfall: During the last week, average daily rainfall over Sri Lanka was 1.7 mm and hydro catchment areas received 8.8 mm.
Rainfall reached 50mm in the south-west shadow of the central mountains. Cyclone “Mocha” made landfall in Myanmar with extreme rain.
Monitored and Predicted Wind: From 9thMay – 15th May, up to 8 m/s of westerly winds were at 850 mb level. During 20th – 26th May, up to 8 m/s of Easterly winds are expected at 850 mb. Cyclone Mocha long range impact led to strong South-westerly wind over SL.
Monitored Sea and Land Temperature: Sea surface temperature around Sri Lanka was about 0.5 – 1 degree above the seasonal norm. Land surface temperature remained near normal.
Interpretation
Monitoring
Rainfall: During the last two weeks, there had been very heavy rainfall over Ratnapure.
Daily Average Rainfall in the Met stations for previous week of (11th May – 17th May) = 1.7 mm
Maximum Daily Rainfall: 48.0 mm & Minimum Daily Rainfall: 0.0 mm.
Wind: Westerly winds prevailed in the sea area and around the island last week.
Temperatures: The temperature anomalies were below normal for some parts of the Northern, North Central, and Eastern provinces and normal for rest of the country driven by the warm SST’s.
Prediction
Rainfall: During the next week (18th May – 24th May), fairly heavy rainfall (≥ 55 mm) is predicted for the Western and Sabaragamuwa provinces and less rainfall is predicted for rest of the country.
Temperatures: The temperature will remain above normal for some parts of the Northern, Eastern, North Central, Southern, and Uva provinces during 20th May – 26th May.
Teleconnections: ENSO-neutral conditions are expected to continue through the Northern Hemisphere spring, followed by a 90% chance of El Nino developing during May-July 2023.
MJO shall moderatly suppress the rainfall during 17th May – 2nd June for Sri Lanka.
Seasonal Precipitation: The precipitation forecast for the June-July-August, 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 |
