Climate Bulletin For Sri Lanka (26 August 2022)

 

Highlights          

 • Heavy rainfall is predicted for central and sabaragamuwa provinces and less rainfall is expected for the rest of the country during 26th - 31st August.

 • During the last week, the average daily rainfall over Sri Lanka was 1.9 mm and hydro catchment areas have received 6.8 mm on average.

 • From 16th- 22nd August, westerly to south-westerly  of 10m/s winds were experienced at 850 mb level over the island. Up to 10m/s of south-westerlies expected for the next week.

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

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Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 25^th August – 31^st August:

Total rainfall by Provinces: 

• > 100 mm - Central, Sabaragamuwa
•    95 mm - Southern, Western, Uva
•    85 mm - Eastern
•    75 mm - North-central, North-western, Northern

From 1^st September – 7^th September:

Total rainfall by Provinces: 

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

MJO based OLR predictions:

For the next 15 days: 

MJO shall slightly enhance the rainfall during 25^th August - 8^th September. 

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: August 17, 2022 

Equatorial sea surface temperatures (SSTs) are below average across most of the Pacific Ocean in mid-August. The tropical Pacific atmosphere is consistent with La Niña. A large majority of the models indicate, a La Niña is favored to continue through 2022 with the odds for La Niña decreasing into the Northern Hemisphere late summer (July - September 2022) before increasing through the Northern Hemisphere fall and early winter 2022.

Indian Sea Sate

Sea surface temperature around Sri Lanka was above 0.5℃ to the north and south 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 fairly heavy rainfall over the following area: Nuwara Eliya 

Daily Average Rainfall in the Met stations for previous week of (17^th Aug - 24^th Aug) = 1.9 mm

Rmax: 29.3 mm & Rmin: 0.0 mm.

Region	Average rainfall for the Last 8 days
Northern Plains	2.4 mm
Eastern	1.3 mm
Western	2.8 mm
Southern Plains	0.0 mm

The Hydro Catchment Areas recorded 6.8 mm of average rainfall for the last week

Rmax: 96.5 mm & Rmin: 0.0 mm. 

Wind:

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

Temperature: 

The temperature anomalies were above normal for the Sabaragamuwa and Central provinces, driven by the warm SST’s.

Predictions

Rainfall:

During the next week (26^th - 31^st August) heavy rainfall is predicted for Central and Sabaragamuwa provinces and fairly heavy rainfall is expected for the rest of the country.

Temperature:

The temperature will remain slightly above normal to the East and North of the island during 26^th August – 1^st September. 

Teleconnections:

La Niña - La Niña is favored to continue through 2022 with the odds for La Niña decreasing into the Northern Hemisphere late summer (July-September 2022) before increasing through the Northern Hemisphere fall and early winter 2022.

MJO shall slightly enhance the rainfall during 25^th August - 8^th September. 

Seasonal Precipitation: 

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