Climate Bulletin For Sri Lanka (9 September 2022)

Highlights          

 • Moderate rainfall is predicted for the Western province, and less rainfall is expected for the rest of the country during 9th-13th September.

 • During the last week, the average daily rainfall over Sri Lanka was 12.7 mm and hydro catchment areas received 80.9 mm on average.

 • From 29th August- 4th September, up to 10m/s of  South-westerlies were experienced at 850 mb level over the island. South-westerly winds are expected next week.

 •  Sea surface temperature around Sri Lanka was above 0.5℃ to the North of Sri Lanka. Land surface temperature remained near normal.

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Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 7^th September – 13^th September:

Total rainfall by Provinces: 

•    35 mm - Western, Sabaragamuwa
• < 15 mm - North Western, Central, Southern

From 14^th September – 20^th September:

Total rainfall by Provinces: 

•    35 mm - Central, Sabaragamuwa
•    25 mm - Western, Uva
• < 15 mm - Southern, Eastern

MJO based OLR predictions:

For the next 15 days: 

MJO shall near neutral during 7^th September – 16^th September and slightly suppress rainfall during 17^th September – 21^st September.

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: September 5, 2022 

Equatorial sea surface temperatures (SSTs) are below average across most of the Pacific Ocean in Early-September. The tropical Pacific atmosphere is consistent with La Niña. A large majority of the models indicate, La Niña is expected to continue, with chances for La Niña gradually decreasing from 86% in the coming season to 60% during December-February 2022-23.

Indian Sea Sate

Sea surface temperature around Sri Lanka was above 0.5℃ to the North of Sri Lanka. 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 area: Ratnapura

Daily Average Rainfall in the Met stations for previous week of (30^th Aug - 6^th Sep) = 12.7 mm

Rmax: 247.1 mm & Rmin: 0.0 mm.

Region	Average rainfall for the Last 8 days
Northern Plains	5.0 mm
Eastern	9.2 mm
Western	25.7 mm
Southern Plains	1.7 mm

The Hydro Catchment Areas recorded 80.9 mm of average rainfall for the last week

Rmax: 207.4 mm & Rmin: 0.0 mm.. 

Wind:

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

Temperature: 

The temperature anomalies were below for the northern half of the island and were even lower in the North Central region of the island, driven by the warm SST’s.

Predictions

Rainfall:

During the next week (9^th- 13^th September) moderate rainfall is predicted for the Western province, and less rainfall is expected for the rest of the country.

Temperature:

The temperature will remain slightly above normal for the Northern, North Central, Uva and Eastern provinces during 8^th September – 14^th September.

Teleconnections:

La Niña is expected to continue, with chances for La Niña gradually decreasing from 86% in the coming season to 60% during December-February 2022-23.

MJO shall near neutral during 7^th September – 16^th September and slightly suppress rainfall during 17^th September – 21^st September.

Seasonal Precipitation: 

The precipitation forecast for the September-October-November season shows a higher tendency for below-normal precipitation for the country.