Climate Bulletin For Sri Lanka (22 October 2021)

Highlights          

                   

 • Fairly heavy rainfall is predicted for the entire island during 22nd - 26th Oct. Greater likelihood of dry tendency is predicted for southern Sri Lanka from Oct to Dec.

 • Fairly heavy rainfall was observed in the Central and Uva provinces with max of 77.3 mm in Nuwara Eliya district on 11th Oct according to ground observations.

 •  From 12th Oct - 19th Oct, up to 25 km/h Westerlies to Southwesterlies were experienced across the island.

 •  Sea surface temperature was observed to be neutral all around Sri Lanka.

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Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 20^th – 26^th  October: 

Total rainfall by Provinces

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

From 27^th October – 2^nd  November: 

Total rainfall by Provinces:

• 115 mm - Sabaragamuwa, Western
• 105 mm - Central, Eastern, Northern, North Central
•  95 mm - Southern, North Western, Uva

MJO based OLR predictions:

For the next 15 days: 

MJO shall be neutral during 20^th - 24^th Oct and slightly suppressed rainfall during 25^th Oct – 3^rd Nov. 

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: October 13, 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 mid-October. 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 to be neutral all around Sri Lanka. 

Interpretation

Monitoring

Rainfall: 

During the last two weeks, there had been fairly heavy rainfall over the following provinces: Central and Uva. 

Wind: 

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

Temperature: 

The temperature anomalies were above normal by 1⁰C – 3⁰C in the Sabaragamuwa, Southern, Uva 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 (22^nd - 26^th October) fairly heavy rainfall is predicted for the entire island. 

Temperature:

The temperature remains slightly normal during 22^nd – 30^th October for the whole country. 

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 neutral during 20^th - 24^th Oct and slightly suppressed rainfall during 25^th Oct – 3^rd Nov. 

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.