Climate Bulletin For Sri Lanka (30 December 2022)

           

Highlights          

 • Moderately heavy rainfall is predicted for Eastern province and less rainfall is predicted for rest of the country during 29th December - 4th January. Seasonal forecast shows higher tendency for above normal precipitation to the country for  January - March, 2023.

 • During the last week, maximum daily rainfall over Sri Lanka was 106.5 mm & hydro catchment areas received 77.5 mm on maximum. Due to storm (98B), floods and landslides were experienced on 25th Dec in the Kandy district & rainfall in Akurana of 121 mm received till 930 AM was among the highest.

 • From 20th - 26th Dec, up to 10m/s of north easterly winds were experienced at 850 mb level over the island. During the last week, strong winds and rough seas were experienced due to storm (98B) over southwest Bay of Bengal.

 • Sea surface temperature around Sri Lanka was near neutral  to the whole country. Land surface temperature remained near normal. 

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Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 29^th December – 4^th January:

Total rainfall by Provinces:   

• 35 mm - Eastern
• 25 mm - Western, Sabaragamuwa, North Central, Central
• ≤ 15mm - North Western, Uva, Southern, Northern

From 5^th January – 11^th January:

Total rainfall by Provinces:   

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

MJO based OLR predictions:

For the next 15 days: 

MJO shall moderately suppress the rainfall during 29^th December – 2^nd January, slightly suppress the rainfall during 3^rd – 7^th January, and near neutral the rainfall during 8^th – 12^th January for Sri Lanka.

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: December 27, 2022 

Equatorial sea surface temperatures (SSTs) are below average across most of the Pacific Ocean late - December. The tropical Pacific atmosphere is consistent with La Niña. A large majority of the models indicate La Niña is favored to continue into the winter, with equal chances of La Niña and ENSO-neutral during January-March 2023. In February-April 2023, there is a 71% chance of ENSO-neutral.

Indian Sea Sate

Sea surface temperature around Sri Lanka was near neutral to the whole country in 21^st December, 2022. Across the Indian Ocean, a classical negative Indian Ocean Dipole prevails as is typical during a La Niña.

 

Interpretation

Monitoring

Rainfall: 

During the last two weeks, there had been heavy rainfall over the following areas: Batticaloa, Kegalle, Puttalam

Daily Average Rainfall in the Met stations for previous week of (21^st December – 28^th December) = 10.1 mm

Rmax: 106.5 mm & Rmin: 0.0 mm.

Region	Average rainfall for the Last 8 days
Northern Plains	10.5 mm
Eastern	10.2 mm
Western	13.3 mm
Southern Plains	3.2 mm

The Hydro Catchment Areas recorded 12.3 mm of average rainfall for the last week

Rmax: 77.5 mm & Rmin: 0.0 mm.

Wind:

North easterly winds prevailed in the sea area and around the island last week.

Temperature: 

The temperature anomalies were above normal for some parts of the Sabaragamuwa province, driven by the warm SST’s.

Storm: 

The storm '98B' originated as a low pressure area over the southwest Bay of Bengal and intensified into the depression (D) on 22^nd December. Then it moved west-southwestwards and centered at Southwest Bay of Bengal close to east coast of Sri Lanka. Then it cut across the island on 25^th December, causing heavy rainfall over Eastern, Central, and Western provinces of Sri Lanka. 

Predictions

Rainfall:

During the next week (29^th Dec – 4^th Jan), moderately heavy rainfall is predicted for the Eastern province; and less rainfall is expected for the rest of the country.

Temperature:

The temperature will remain below normal for some parts of the Central, and Uva provinces during 30^th December – 5^th January.

Teleconnections:

La Niña is favored to continue into the winter, with equal chances of La Niña and ENSO-neutral during January-March 2023.

MJO shall moderately suppress the rainfall during 29^th December – 2^nd January, slightly suppress the rainfall during 3^rd – 7^th January, and near neutral the rainfall during 8^th – 12^th January for Sri Lanka.

Seasonal Precipitation: 

The precipitation forecast for the January-February-March 2023 season shows a higher tendency for above-normal precipitation to the country.