Climate Bulletin For Sri Lanka (25 November 2022)

      

Highlights          

 • Moderately heavy (≥ 40 mm) rainfall is predicted for the Sabaragamuwa, Uva, and Eastern provinces during 24th - 30th November.

 • During the last week, the average daily rainfall over Sri Lanka was 0.8 mm & hydro catchment areas received 0.8 mm on average and the highest average rainfall (1.6 mm) was received to the Eastern plains of the country.

 • From 14th - 20th Nov, up to 6m/s of north-easterly winds were experienced at 850 mb level over the island. Wind Direction has changed from arriving from South-West to arriving from North East.

 • 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 24^th November – 30^th November:

Total rainfall by Provinces:   

•   70 mm - Uva, Sabaragamuwa
•   40 mm - Eastern
•   20 mm - Southern, Central, North Western, North Central
• ≤ 10 mm - Northern, Western

MJO based OLR predictions:

For the next 15 days: 

MJO shall moderately suppress the rainfall during 23^rd – 27^th November, slightly suppress the rainfall during 28^th November – 2^nd December, and remain near normal during 3^rd – 7^th December for Sri Lanka.

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: November 21, 2022 

Equatorial sea surface temperatures (SSTs) are below average across most of the Pacific Ocean late - 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 the country in 16^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, Avissawella

Daily Average Rainfall in the Met stations for previous week of (15^th November – 22^nd November) = 0.8 mm

Rmax: 30.5 mm & Rmin: 0.0 mm.

Region	Average rainfall for the Last 8 days
Northern Plains	0.0 mm
Eastern	1.6 mm
Western	0.5 mm
Southern Plains	0.8 mm

The Hydro Catchment Areas recorded 0.8 mm of average rainfall for the last week

Rmax: 14.8 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 some parts of the North Central, North Eastern and Central provinces, driven by the warm SST’s.

Predictions

Rainfall:

During the next week (24^th – 30^th November), moderately heavy (≥ 40 mm) rainfall is predicted for the Uva, Sabaragamuwa, and Eastern 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 24^th – 30^th 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 23^rd – 27^th November, slightly suppress the rainfall during 28^th November – 2^nd December, and remain near normal during 3^rd – 7^th December for Sri Lanka.

Seasonal Precipitation: 

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