Climate Bulletin For Sri Lanka (1 October 2021)

 

Highlights          

                   

 • Heavy rainfall is predicted in Central, North Western, Sabaragamuwa, Southern, Uva and Western provinces during 1st-5th Oct. Greater likelihood of dry tendency than normal is predicted for southern Sri Lanka from Oct to Dec.

 •  Very heavy rainfall was experienced in Central and Sabaragamuwa provinces with max of 210.2 mm in Kandy district on 24th Sept.

 •  From 21st - 27th Sept, up to 50 km/h Southwesterlieswere experienced across the island.

 • Sea surface temperature was observed above 0.5℃ to the East, South and 1.0 0C to the North, West of Sri Lanka.

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Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 29^th  September – 5^th  October: 

Total rainfall by Provinces

• 135 mm - Sabaragamuwa, Western
• 115 mm - Central, North-Western, Southern
• 105 mm - Uva
•  85 mm - Eastern, North-Central
•  75 mm - Northern

From 6^th – 12^th  October: 

Total rainfall by Provinces:

• 105 mm - Sabaragamuwa
•  95 mm - Western
•  85 mm - Central, Southern
•  75 mm - North-Western, Uva
•  65 mm - Eastern, Northern, North-Central

MJO based OLR predictions:

For the next 15 days: 

MJO shall be active, thus giving slightly enhanced rainfall during 1^st – 13^th October. 

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: September 22, 2021 

Equatorial SSTs were near-to-below average across most of the equatorial Pacific Ocean, and were above average in the western Pacific Ocean in the late-September. A large majority of the model forecasts predict a transition from ENSO-neutral to La Niña is favored in the next couple of months and La Niña to continue through the Northern Hemisphere fall and winter.

Indian Sea Sate

Sea surface temperature was observed above 0.5℃ to the East, South and 1.0⁰C to the North, West of Sri Lanka. 

Interpretation

Monitoring

Rainfall: 

During the last two weeks, there had been very heavy rainfall over the following Provinces: Sabaragamuwa and Central.

Wind: 

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

Temperature: 

The temperature anomalies were in between 1⁰C – 3⁰C in Central, Sabaragamuwa, North-Central, North-Western, Southern and Western provinces while near-neutral for the rest of the country last week, driven by the warm SST’s.

Predictions

Rainfall:

During the next week (1^st – 5^th October) heavy rainfall is predicted for Central, North Western, Sabaragamuwa, Southern, Uva and Western provinces. 

Temperature:

The temperature remains slightly normal for October. During 1^st – 9^th October, the temperature remains high especially in the Eastern, Southern and Uva provinces and low in Central province.

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 enhanced rainfall during 1^st – 13^th October. 

Seasonal Precipitation: 

October to December is the main rainfall season in Sri Lanka. The consensus predictions have 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.