Climate Bulletin For Sri Lanka ( 24 February 2023)

 

Highlights          

 • Fairly heavy rainfall is predicted for the Southern and Easter provinces during 23 Feb – 1 Mar. The seasonal forecast shows a higher tendency for above-normal precipitation for southern half of the country from March - May, 2023.

 • During the last week, maximum daily rainfall over Sri Lanka was 237 mm in Ampara and  hydro catchment areas received 3.7 mm on average. Highest average rainfall 9.1 mm/day received to Eastern plains of the country.

 • From 14 - 20 Feb, up to 6 m/s of north easterly winds were experienced at 850 mb level over the island. During 24 Feb- 2 Mar north easterly winds are expected for the country.

 • Sea surface temperature around Sri Lanka was below normal  for northern half of the island. Land surface temperature remained near normal. 

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Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 23^rd February – 1^st March:

Total rainfall by Provinces:    

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

From 2^nd March – 8^th March:

Total rainfall by Provinces:   

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

MJO based OLR predictions:

For the next 15 days: 

MJO shall moderately suppress the rainfall during 23^th February – 4^th March, and significantly suppress the rainfall during 5^th March – 9^th March for Sri Lanka.

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: February 20, 2023 

Equatorial sea surface temperatures (SSTs) are below average across most of the Pacific Ocean mid - February. The tropical Pacific atmosphere is consistent with La Niña. A large majority of the models indicate ENSO-neutral conditions will begin within the next couple of months, and persist through the Northern Hemisphere spring and early summer.

Indian Sea Sate

Sea surface temperature around Sri Lanka was below - 0.5℃ to the northern half of the country in 1^st February, 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 very heavy rainfall over the following area:

Ampara

Daily Average Rainfall in the Met stations for previous week of (14^th February – 21^st February) = 4.5 mm

Rmax: 107.2 mm & Rmin: 0.0 mm.

Region	Average rainfall for the Last 8 days
Northern Plains	0.4 mm
Eastern	9.1 mm
Western	4.9 mm
Southern Plains	0.9 mm

The Hydro Catchment Areas recorded 3.7 mm of average rainfall for the last week

Rmax: 55.8 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 Northern half of the island and above normal for the Sabaragamuwa province, driven by the warm SST’s.

Predictions

Rainfall:

During the next week (23^rd February – 1^st March), Fairly heavy rainfall (55 mm) is predicted for the Southern and Eastern provinces, and less rainfall is expected for rest of the country.

Temperature:

The temperature will remain above normal for some parts of the Sabaragamuwa, North western, North central and Uva provinces and below normal for Nuwara Eliya district during 25^th February – 5^th March.

Teleconnections:

ENSO-neutral conditions will begin within the next couple of months, and persist through the Northern Hemisphere spring and early summer.

MJO shall moderately suppress the rainfall during 23^th February – 4^th March, and significantly suppress the rainfall during 5^th March – 9^th March for Sri Lanka.

Seasonal Precipitation: 

The precipitation forecast for the March-April-May 2023 season shows a higher tendency of above-normal precipitation for southern half of the country.