Highlights

Rainfall Prediction: Fairly heavy rainfall is predicted for Central, Southern, Western and Sabaragamuwa provinces during 15th – 19th Oct. Greater likelihood of dry tendency is predicted for southern Sri Lanka from Oct to Dec

Monitored Rainfalls: Very heavy rainfall was observed in the Northern and North Western provinces with max of 200.3 mm in Jaffna district on 10th Oct according to ground observations.

Monitored  Wind: From 5th Oct – 12th Oct, up to 40 km/h Southwesterlies were experienced across the island.

Monitored  Sea Surface: Sea surface temperature was observed above 0.5℃ all around Sri Lanka.

Climate Bulletin for Sri Lanka (Week of  15 – 22  Oct 2021)
Climate Bulletin for Sri Lanka (Week of  15 – 22  Oct 2021)

Interpretation

Monitoring

Rainfall:  During the last two weeks, there had been very heavy rainfall over the Northern and North Western provinces and heavy rainfall over the Central, Southern and Western provinces.

Wind: South westerly winds prevailed in the sea area and around the island during last week.

Temperatures: The temperature anomalies were below normal by 10C – 30C in the North Central province while near-neutral for the rest of the country last week, driven by the warm SST’s.

Prediction

Rainfall: During the next week (15th – 19th October) fairly heavy rainfall is predicted for Central, Sabaragamuwa, Southern and Western provinces.

Temperatures: The temperature remains slightly normal for October. During 15th – 23rd October, the temperature remains high especially in the Eastern, North Central and Uva provinces.

Teleconnections: La Nina -The SST forecast indicates that ENSO-neutral are present and a transition from ENSO-neutral to La Niña is favored in the next couple of months. MJO shall be active, thus giving slightly suppressed rainfall during 13th 27th October.

Seasonal Precipitation: October to December is the main rainfall season in Sri Lanka. The consensus predictions has switched from neutral to favoring a dry tendency.  A dry tendency can hurt agricultural production and it adds to farmer difficulties due to the fertilizer bans. However, since this is the wet season the impact will not be as severe. However, the bigger impact shall be that it shall reduce the generated hydropower in the coming months. This can hurt the economy due to the scarcity in Foreign Exchange within the country due to the Central Bank regulations.

Understanding the Forecast

Rainfall (During 24 hours of period)
Light ShowersLess than 12.5 mm
Light to ModerateBetween 12.5 mm and 25 mm
ModerateBetween 25 mm and 50 mm
Fairly HeavyBetween 50 mm and 100 mm
HeavyBetween 100 mm and 150 mm
Very HeavyMore than 150 mm