Climate Bulletin For Sri Lanka (21 April 2023)

  

Highlights          

 • Fairly heavy rainfall is predicted for the Sabaragamuwa, Southern, Western, Central and North Western provinces and less rainfall is expected for rest of the country during 20 th Apr - 26th Apr.

 • During the last week, average daily rainfall over Sri Lanka was 2.0 mm and  hydro catchment areas received 4.3 mm.

 • From 11th - 17th Apr, up to 5 m/s of Easterly winds were experienced at 850 mb level over the island. During 21st Apr - 27th Apr, up to 3 m/s of South Easterly winds are expected for the country.

 • Sea surface temperature was about one degree above the seasonal norm. The maximum land surface across Sri Lanka ranged from 30 - 35ºC with a drop in the hills. 

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Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 20^th April – 26^th April:

Total rainfall by Provinces:    

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

From 26^th April – 3^rd April:

Total rainfall by Provinces:   

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

MJO based OLR predictions:

For the next 15 days: 

MJO shall slightly suppress the rainfall during 20^th – 24^th April, and slightly enhance the rainfall during 25^th April – 4^th May for Sri Lanka.

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: April 17, 2023 

Equatorial sea surface temperatures (SSTs) are near-to-above average across most of the Pacific Ocean mid- April. The tropical Pacific atmosphere is consistent with ENSO-neutral conditions. A large majority of the models indicate ENSO-neutral conditions are expected to continue through the Northern Hemisphere spring, followed by a 62% chance of El Nino developing during May-July 2023.

Indian Sea Sate

Sea surface temperature around Sri Lanka was near normal to the country in 21^st – 27^th March, 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 area:  Bandarawela

         

Daily Average Rainfall in the Met stations for previous week of (12^th April – 19^th April) = 2.0 mm

Maximum Daily Rainfall: 71.5 mm & Minimum Daily Rainfall: 0.0 mm. 

Region	Average rainfall for the Last 8 days
Northern Plains	1.6 mm
Eastern	1.8 mm
Western	2.9 mm
Southern Plains	0.0 mm

The Hydro Catchment Areas recorded 4.3 mm of average rainfall for the last week.

Maximum Daily Rainfall: 64.0 mm & Minimum Daily Rainfall: 0.0 mm.

Wind:

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

Temperature: 

The temperature anomalies were above normal for some parts of the Sabaragamuwa province and near normal for rest of the country driven by the warm SST’s.

Predictions

Rainfall:

During the next week (20^th April – 26^th April), fairly heavy rainfall (≥ 55 mm) is predicted for the Southern, Sabaragamuwa, Western, Central, and North Western provinces, and less rainfall is expected for rest of the country.

Temperature:

The temperature will remain above normal for some parts of the Northern, North Western, North Central, Uva, Eastern, and Southern provinces during 21^st April – 27^th April.

Teleconnections:

ENSO-neutral conditions are expected to continue through the Northern Hemisphere spring, followed by a 62% chance of El Nino developing during May-July 2023.

MJO shall slightly suppress the rainfall during 20^th – 24^th April, and slightly enhance the rainfall during 25^th April – 4^th May for Sri Lanka.

Seasonal Precipitation: 

The precipitation forecast for the May-June-July, 2023 season shows near normal precipitation for the country.