Climate Bulletin For Sri Lanka (30 September 2022)

 

Highlights          

 • During the next week (30th September - 4th October) fairly heavy rainfall is predicted for the Sabaragamuwa, Southern and Western provinces, and less rainfall is expected for the rest of the country.

 • During the last week, the average daily rainfall over Sri Lanka was 1.1 mm and hydro catchment areas received 2.1 mm on average.

 • From 19th-25th Sept, up to 10m/s of north-westerly to westerly winds were experienced at 850 mb level over the island. westerly winds are expected next week.

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

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Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 28^th September – 4^th October:

Total rainfall by Provinces:   

•   65 mm - Sabaragamuwa 
•   55 mm - Western, Southern
•   35 mm - Central, North Western
• < 25 mm - North Central, Northern, Uva, Eastern

From 5^th October – 11^th October:

Total rainfall by Provinces:

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

MJO based OLR predictions:

For the next 15 days: 

MJO shall near neutral during 28^th September – 12^th October for Sri Lanka.

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: September 21, 2022 

Equatorial sea surface temperatures (SSTs) are below average across most of the Pacific Ocean late-September. The tropical Pacific atmosphere is consistent with La Niña. A large majority of the models indicate, La Niña is favored to continue through Northern Hemisphere winter 2022-23, with a 91% chance in September-November, decreasing to a 54% chance in January-March 2023.

Indian Sea Sate

Sea surface temperature around Sri Lanka was above 0.5℃ to the North and South of the country. 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: Polonnaruwa

Daily Average Rainfall in the Met stations for previous week of (21^st Sep - 27^th Sep) = 1.1 mm

Rmax: 21.1 mm & Rmin: 0.0 mm.

Region	Average rainfall for the Last 8 days
Northern Plains	0.8 mm
Eastern	2.3 mm
Western	0.7 mm
Southern Plains	0.0 mm

The Hydro Catchment Areas recorded 2.1 mm of average rainfall for the last week

Rmax: 58.8 mm & Rmin: 0.0 mm. 

Wind:

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

Temperature: 

The temperature anomalies were below for the north central province, driven by the warm SST’s.

Predictions

Rainfall:

During the next week (30^th September - 4^th October) fairly heavy rainfall is predicted for the Sabaragamuwa, Southern and Western provinces, and less rainfall is expected for the rest of the country.

Temperature:

The temperature will remain above normal for the Uva and Eastern provinces during 1^st October – 9^th October.

Teleconnections:

La Niña is favored to continue through Northern Hemisphere winter 2022-23, with a 91% chance in September-November, decreasing to a 54% chance in January-March 2023.

MJO shall near neutral during 28^th September – 12^th October for Sri Lanka.

Seasonal Precipitation: 

The precipitation forecast for the October-November-December 2022 season shows a higher tendency for below-normal precipitation to the southern half of the country.