Climate Bulletin For Sri Lanka (7 October 2022)

  

Highlights          

 • During the next week (5th - 11th October) moderate rainfall is predicted for the Western, Sabaragamuwa and Central provinces, and less rainfall is expected for the rest of the country.

 • During the last week, the average daily rainfall over Sri Lanka was 3.5 mm and hydro catchment areas received 22.1 mm on average.

 • From 26th Sep-2nd Oct, up to 15m/s of north-westerly winds were experienced at 850 mb level over the island. North-westerly winds are expected next week.

 • Sea surface temperature around Sri Lanka was above 0.5 ℃  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 5^th October – 11^th October:

Total rainfall by Provinces:   

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

From 12^th October – 18^th October:

Total rainfall by Provinces:

• 65 mm - Sabaragamuwa, Western
• 55 mm - Central, Southern, Uva, North Western
• 45 mm - Northern, North Central, Eastern

MJO based OLR predictions:

For the next 15 days: 

MJO shall near neutral during 5^th– 9^th October; slightly suppress rainfall during 10^th – 14^th October and significantly suppress the rainfall during 15^th – 19^th October for Sri Lanka.

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: October 3, 2022 

Equatorial sea surface temperatures (SSTs) are below average across most of the Pacific Ocean early - October. 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 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 very heavy rainfall over the following area: Kegalle

Daily Average Rainfall in the Met stations for previous week of (27^th Sep - 4^th Oct) = 3.5 mm

Rmax: 61.1 mm & Rmin: 0.0 mm.

Region	Average rainfall for the Last 8 days
Northern Plains	1.3 mm
Eastern	1.0 mm
Western	8.0 mm
Southern Plains	0.5 mm

The Hydro Catchment Areas recorded 22.1 mm of average rainfall for the last week

Rmax: 152.8 mm & Rmin: 0.0 mm. 

Wind:

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

Temperature: 

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

Predictions

Rainfall:

During the next week (5^th October - 11^th October) moderate rainfall is predicted for the Western, Sabaragamuwa and Central 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 6^st October – 12^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 5^th– 9^th October; slightly suppress rainfall during 10^th – 14^th October and significantly suppress the rainfall during 15^th – 19^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 in the southern half of the country.