Climate Bulletin For Sri Lanka (19 May 2023)

     

Highlights          

 • Fairly heavy rainfall is predicted for the  Western and Sabaragamuwa provinces and less rainfall is predicted for rest of the country durring 18th May – 24th May.

 • During the last week, average daily rainfall over Sri Lanka was 1.7 mm and  hydro catchment areas received 8.8 mm. Rainfall reached 50mm in the south-west shadow of the central mountains. Cyclone Mocha made landfall in Myanmar with extreme rain. 

 • From 9thMay - 15th May, up to 8 m/s of westerly winds were at 850 mb level. During 20th- 26th May, up to 8 m/s of Easterly winds are expected at 850 mb. Cyclone Mocha long range impact led to strong South-westerly wind over SL.

 • Sea surface temperature around Sri Lanka was about 0.5 - 1 degree above the seasonal norm. Land surface temperature remained near normal.

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Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 18^th May – 24^th May:

Total rainfall by Provinces:    

• 75mm - Western
• 55 mm - Sabaragamuwa
• 45 mm - Southern, North Western
• 25 mm - Central
• 15 mm - Uva
• 25 mm - Northern, North Central, Eastern

From 25^th May – 31^st May:

Total rainfall by Provinces:   

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

MJO based OLR predictions:

For the next 15 days: 

MJO shall moderately suppress the rainfall during 17^th May – 2^nd June for Sri Lanka.

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: May 15, 2023 

Equatorial sea surface temperatures (SSTs) are near-to-above average across most of the Pacific Ocean mid-May. 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 90% chance of El Nino developing during May-July 2023

Indian Sea Sate

Sea surface temperature around Sri Lanka was 0.5ºC above normal to the country except northern half in 25^th April– 1^st May, 2023. 

 

Interpretation

Monitoring

Rainfall:

During the last two weeks, there had been heavy rainfall over the following area:  Rathnapura.

Daily Average Rainfall in the Met stations for previous week of (11^th May – 17^th May) = 1.7 mm

Maximum Daily Rainfall: 48 mm & Minimum Daily Rainfall: 0.0 mm. 

Region	Average rainfall for the Last 8 days
Northern Plains	0.3 mm
Eastern	0.7 mm
Western	4.4 mm
Southern Plains	0.1 mm

The Hydro Catchment Areas recorded 8.0 mm of average rainfall for the last week.

Maximum Daily Rainfall: 78.0 mm & Minimum Daily Rainfall: 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 Northern, North Central, and Eastern provinces and normal for rest of the country driven by the warm SST’s.

Predictions

Rainfall:

During the next week (18^th May – 24^th May), fairly heavy rainfall (≥ 55 mm) is predicted for the Western and Sabaragamuwa provinces and less rainfall is predicted for rest of the country.

Temperature:

The temperature will remain above normal for some parts of the Northern, Eastern, North Central, Southern, and Uva provinces during 20^th May – 26^th May.

Teleconnections:

ENSO-neutral conditions are expected to continue through the Northern Hemisphere spring, followed by a 90% chance of El Nino developing during May-July 2023.

MJO shall moderately suppress the rainfall during 17^th May – 2^nd June for Sri Lanka.

Seasonal Precipitation: 

The precipitation forecast for the June-July-August, 2023 season shows above normal precipitation for the country.