Climate Bulletin For Sri Lanka (2 December 2022)

       

Highlights          

 • Heavy (> 100 mm) rainfall is predicted for the Eastern province and fairly heavy (≥ 55 mm) rainfall is predicted for the rest of the country during 30thNov - 6th Dec.

 • During the last week, the average daily rainfall over Sri Lanka was 0.6 mm & hydro catchment areas received 4.5 mm on average and the highest average rainfall (4.3 mm) was received to the Eastern plains of the country.

 • From 21st - 27th Nov, up to 6m/s of westerly winds were experienced at 850 mb level over the island. Wind Direction has changed from arriving from South-West to arriving from North East.

 • Sea surface temperature around Sri Lanka was near neutral to the whole country. Land surface temperature remained near normal. 

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Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 30^th November – 6^th December:

Total rainfall by Provinces:   

• 105 mm - Eastern
•  95 mm - Uva
•  85 mm - Sabaragamuwa
•  75 mm - Southern, Western, Central, Northern, North Central
•  55 mm - North Western

From 7^th December – 13^th December:

Total rainfall by Provinces:   

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

MJO based OLR predictions:

For the next 15 days: 

MJO shall near neutral the rainfall during 30^th Nov - 4^th Dec, slightly increase the rainfall during 5^th– 9^th December, and moderately increase the rainfall during 10^th – 14^th December for Sri Lanka.

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: November 28, 2022 

Equatorial sea surface temperatures (SSTs) are below average across most of the Pacific Ocean early - December. The tropical Pacific atmosphere is consistent with La Niña. A large majority of the models indicate La Niña is favored to continue through during the Northern Hemisphere winter (December-February) 2022-23, with a transition to ENSO-neutral favored in February-April 2023 (57% chance).

Indian Sea Sate

Sea surface temperature around Sri Lanka was near neutral to the whole country in 23^rd November, 2022. 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: Wellawaya

Daily Average Rainfall in the Met stations for previous week of (22^nd November – 29^th November) =0.6 mm

Rmax: 13.3 mm & Rmin: 0.0 mm.

Region	Average rainfall for the Last 8 days
Northern Plains	0.0 mm
Eastern	4.3 mm
Western	2.1 mm
Southern Plains	2.9 mm

The Hydro Catchment Areas recorded 4.5 mm of average rainfall for the last week 

Rmax: 70.5 mm & Rmin: 0.0 mm.

Wind:

Westerly winds prevailed in the sea area and around the island last week.

Temperature: 

The temperature anomalies were below normal for some parts of the North Central, and North Western provinces, driven by the warm SST’s.

Predictions

Rainfall:

During the next week (30^th Nov – 6^th Dec), heavy (>100 mm) rainfall is predicted for the Eastern province; and fairly heavy (≥ 55 mm) rainfall is expected for the rest of the country.

Temperature:

The temperature will remain below normal for some parts of the Central, Uva, and Sabaragamuwa provinces during 1^st – 7^th December.

Teleconnections:

La Niña is favored to continue through during the Northern Hemisphere winter (December-February) 2022-23, with a transition to ENSO-neutral favored in February-April 2023 (57% chance).

MJO shall near neutral the rainfall during 30^th Nov – 4^th Dec, slightly increase the rainfall during 5^th– 9^th December, and moderately increase the rainfall during 10^th – 14^th December for Sri Lanka.

Seasonal Precipitation: 

The precipitation forecast for the December-January-February 2023 season shows a higher tendency for near-normal precipitation to the country.