Climate Bulletin For Sri Lanka (18 November 2022)

     

Highlights          

 • Fairly heavy (≥ 55 mm) rainfall is predicted for the Sabaragamuwa, Southern, Northern, Western, and Central provinces during 16th - 22nd November.

 • During the last week, the average daily rainfall over Sri Lanka was 14.4 mm & hydro catchment areas received 9.4 mm on average and the highest average rainfall (17 mm) was received to the Eastern and Southern plains of the country.

 • From 7th - 13th Nov, up to 6m/s of north-easterly winds were experienced at 850 mb level over the island. During 17th - 23rd Nov, north - westerly winds are expected to the country .

 • Sea surface temperature around Sri Lanka was above normal to the Southern half of the country. Land surface temperature remained near normal.

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Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 16^th November– 22^nd November:

Total rainfall by Provinces:   

•   85 mm - Southern, Sabaragamuwa
•   75 mm - Northern, Western
•   55 mm - Central
•   25 mm - Eastern, Uva
• < 25 mm - North Western, North Central

MJO based OLR predictions:

For the next 15 days: 

MJO shall moderately suppress the rainfall during 16^th– 25^th November and slightly suppress the rainfall during 26^th – 30^th November for Sri Lanka.

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: November 14, 2022 

Equatorial sea surface temperatures (SSTs) are below average across most of the Pacific Ocean mid - November. The tropical Pacific atmosphere is consistent with La Niña. A large majority of the models indicate La Niña is favored to continue through during the Northern Hemisphere winter (December-February) 2022-23, with a transition to ENSO-neutral favored in February-April 2023 (57% chance).

Indian Sea Sate

Sea surface temperature around Sri Lanka was above 0.5℃ to the Southern half of country in 9^th November, 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 very heavy rainfall over the following areas: Kegalle, Jaffna, and Avissawella

Daily Average Rainfall in the Met stations for previous week of (8^th November – 15^th November) = 14.4 mm

Rmax: 133.9 mm & Rmin: 0.0 mm.

Region	Average rainfall for the Last 8 days
Northern Plains	14.8 mm
Eastern	17.3 mm
Western	12.5 mm
Southern Plains	17.9 mm

The Hydro Catchment Areas recorded 9.4 mm of average rainfall for the last week

Rmax: 92.9 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 below normal for the North Central province and some parts of the North Eastern, Eastern and Central provinces, driven by the warm SST’s.

Predictions

Rainfall:

During the next week (16^th – 22^nd November), fairly heavy (≥ 55 mm) rainfall is predicted for the Southern, Sabaragamuwa, Northern, Western, and Central provinces; 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 17^th – 23^rd November.

Teleconnections:

La Niña is favored to continue through during the Northern Hemisphere winter (December-February) 2022-23, with a transition to ENSO-neutral favored in February-April 2023 (57% chance).

MJO shall moderately suppress the rainfall during 16^th– 25^th November and slightly suppress the rainfall during 26^th – 30^th November for Sri Lanka.

Seasonal Precipitation: 

The precipitation forecast for the December-January-February 2023 season shows a higher tendency for above-normal precipitation in the north half of the country.