Climate Bulletin For Sri Lanka (23 September 2022)

  

Highlights          

 • During the next week (23rd- 27th September) moderate rainfall is predicted for the Sabaragamuwa and Western  province, and less rainfall is expected for the rest of the country.

 • During the last week, the average daily rainfall over Sri Lanka was 0.4 mm and hydro catchment areas received 0.1 mm on average.

 • From 12th- 18th September, up to 8m/s of  south-westerly  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 the country. Land surface temperature remained near normal.

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Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 21^st September – 27^th September:

Total rainfall by Provinces:  

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

From 28^th September – 4^th October:

Total rainfall by Provinces:

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

MJO based OLR predictions:

For the next 15 days: 

MJO shall near neutral during 21^st September – 25^th September and start to slightly enhance rainfall during 26^th September onwards for Sri Lanka.

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: September 14, 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 above 0.5℃ to the North 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 light to moderate rainfall over the following area: Galle

Daily Average Rainfall in the Met stations for previous week of (13^th Sep - 20^th Sep) = 0.4 mm

Rmax: 19.4 mm & Rmin: 0.0 mm.

Region	Average rainfall for the Last 8 days
Northern Plains	0.0 mm
Eastern	0.5 mm
Western	0.6 mm
Southern Plains	0.0 mm

The Hydro Catchment Areas recorded 0.1 mm of average rainfall for the last week

Rmax: 3.7 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 province, driven by the warm SST’s.

Predictions

Rainfall:

During the next week (23^rd- 27^th September) moderate rainfall is predicted for the Sabaragamuwa and Western 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 23^rd September – 29^th 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 during 21^st September – 25^th September and start to heavily enhance rainfall during 26^th September onwards 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.