Climate Bulletin For Sri Lanka ( 3 February 2023)

                

Highlights          

 • Fairly heavy rainfall is predicted for the Eastern province, and moderately heavy rainfall is expected for rest of the country during 3rd Feb - 9th Feb.

 • During the last week, maximum daily rainfall over Sri Lanka was 130.7 mm by storm (90B), and  hydro catchment areas received 65.0 mm. Highest average rainfall 9.1 mm/day received to northern plains of the country.

 • From 25th - 31st Jan, up to 8m/s of north easterly winds were experienced at 850 mb level over the island. During the last week, strong winds and rough seas were experienced due to storm (90B) over southwest Bay of Bengal.

 • Sea surface temperature around Sri Lanka was near-neutral  for the entire island. Land surface temperature remained near normal. 

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Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 3^rd February – 9^th February:

Total rainfall by Provinces:    

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

From 10^th February – 16^th February:

Total rainfall by Provinces:   

• 25 mm - Eastern
• 15 mm - Northern
• ≤ 5 mm - Central, Western, Southern, Sabaragamuwa, Uva, North Central, North Western

MJO based OLR predictions:

For the next 15 days: 

MJO shall moderately enhance the rainfall during 3^rd – 7^th February, slightly enhance the rainfall during 8^th – 12^th February, and near normal the rainfall during 13^th – 17^th February for Sri Lanka.

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: January 30, 2023 

Equatorial sea surface temperatures (SSTs) are below average across most of the Pacific Ocean late - January. The tropical Pacific atmosphere is consistent with La Niña. A large majority of the models indicate a transition from La Niña to ENSO-neutral anticipate during the February-April 2023 season by Northern Hemisphere spring (March-May 2023), the chance for ENSO-neutral is 82%.

Indian Sea Sate

Sea surface temperature around Sri Lanka was near neutral for the whole country in 25^th January, 2023. 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 areas:

Vavuniya, Batticaloa

Daily Average Rainfall in the Met stations for previous week of (25^th January – 1^st February) = 6.0 mm

Rmax: 130.7 mm & Rmin: 0.0 mm

Region	Average rainfall for the Last 8 days
Northern Plains	9.1 mm
Eastern	8.1 mm
Western	1.9 mm
Southern Plains	2.2 mm

The Hydro Catchment Areas recorded 2.7 mm of average rainfall for the last week

Rmax: 65.0 mm & Rmin: 0.0 mm.

Wind:

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

Temperature: 

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

Storm: 

The storm '90B' originated as a low pressure area over the southwest Bay of Bengal. Then it moved west-southwestwards and centered close to the east coast of Sri Lanka near Trincomalee on 31^st January. It cut across the island on 2^nd February as a low pressure area, causing heavy rainfall over the Northern, Eastern, and Uva provinces of Sri Lanka. 

Predictions

Rainfall:

During the next week (3^rd February – 9^th February), fairly heavy rainfall (≥ 65 mm) is predicted for the Eastern province, and moderately heavy rainfall is expected for rest of the country.

Temperature:

The temperature will remain below normal for some parts of the Central and Uva provinces during 4^th – 10^th February.

Teleconnections:

A transition from La Niña to ENSO-neutral is anticipated during the February-April 2023 season by Northern Hemisphere spring (March-May 2023), the chance for ENSO-neutral is 82%.

MJO shall moderately enhance the rainfall during 3^rd – 7^th February, slightly enhance the rainfall during 8^th – 12^th February, and near normal the rainfall during 13^th – 17^th February for Sri Lanka.

Seasonal Precipitation: 

The precipitation forecast for the February-March-April 2023 season shows a higher tendency of near-normal precipitation for the country.