Climate Bulletin For Sri Lanka (16 September 2022)

 

Highlights          

 • During the next week (16th- 20th September) moderate rainfall is predicted for the Western and Sabaragamuwa provinces, and less rainfall is expected for rest of the country.

 • During the last week, the average daily rainfall over Sri Lanka was 0.5 mm and hydro catchment areas received 1.6 mm on average.

 • From 5th- 11th September, up to 15m/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 around 25 - 30℃ to the North and West of the country. Land surface temperature remained near normal.

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Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 14^th September – 20^th September:

Total rainfall by Provinces: 

•   35 mm - Western, Sabaragamuwa
• < 25 mm - North Western, Central, Southern 

From 21^st September – 27^th September:

Total rainfall by Provinces:

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

MJO based OLR predictions:

For the next 15 days: 

MJO shall near neutral for Sri Lanka during 14^th September – 28^th September.

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: September 8, 2022 

Equatorial sea surface temperatures (SSTs) are below average across most of the Pacific Ocean early-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 around 25 - 30℃ to the North and West 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 fairly heavy rainfall over the following area: Colombo

Daily Average Rainfall in the Met stations for previous week of (6^th Sep - 13^th Sep) = 0.5 mm

Rmax: 16.2 mm & Rmin: 0.0 mm.

Region	Average rainfall for the Last 8 days
Northern Plains	0.0 mm
Eastern	0.0 mm
Western	1.4 mm
Southern Plains	0.1 mm

The Hydro Catchment Areas recorded 1.6 mm of average rainfall for the last week

Rmax: 36.9 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 provinces like Uva and Sabaragamuwa, driven by the warm SST’s.

Predictions

Rainfall:

During the next week (16^th- 20^th September) moderate rainfall is predicted for the Western and Sabaragamuwa provinces, and less rainfall is expected for the rest of the country.

Temperature:

The temperature will remain above normal for the Northern, North central, Uva and Eastern provinces during 16^th September – 22^nd September.

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 for Sri Lanka during 14^th September – 28^th September.

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.