Climate Bulletin For Sri Lanka (25 August 2023)

     

Highlights          

 • Light showers (25 mm) are predicted for the Sabaragamuwa, Southern, Northern, Uva provinces during 24 - 30 Aug. Fairly heavy rainfall (≥ 55mm) is predicted for the Sabaragamuwa, Southern, Western, Uva, Central, North Western provinces during 31 Aug - 6 Sep. 

 • During the last week, average daily rainfall over Sri Lanka was 'light' (0.9 mm) and  hydro catchment areas received  'light' (1.2 mm) showers.

 • From 15 - 21 Aug, up to 10 m/s of northwest-westerly winds were at 850 mb (1.5 km). During 25 - 31 Aug, up to 10 m/s of northwest-southwesterly winds are expected at 850 mb (1.5 km). 

 • Sea surface temperature around Sri Lanka was 0.5 - 2ºC above normal. From 16 - 23 Aug, maximum daily temperature was recorded in Vavuniya (38.5ºC), Polonnaruwa (38.1ºC) and Pottuvil (37.5ºC).

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Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 24^th August – 30^th August:   

Total rainfall by Provinces

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

From 31^st August – 6^th September:   

Total rainfall by Provinces

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

MJO based OLR predictions:

For the next 15 days: 

MJO shall near neutral the rainfall during 23^rd August - 1^st September and slightly enhance the rainfall during 2^nd - 6^th September for Sri Lanka.

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: August 21, 2023 

El Nino Mode has set in according to NOAA since 8^th of June. Equatorial sea surface temperatures (SSTs) are above average across the central and eastern Pacific Ocean mid-August. El Niño conditions will continue through the Northern Hemisphere winter (with greater than a 95% chance through December 2023-February 2024).

Indian Sea Sate

Sea surface temperature around Sri Lanka was 0.5 ℃ above normal to the country in 1^st - 7^th August, 2023. A positive Dipole Mode has set in across the Indian Ocean since 8^th of June.

 

Interpretation

Monitoring

Rainfall:

During the last two weeks, there had been fairly heavy rainfall over the following area: Polonnaruwa

Daily Average Rainfall in the Met stations for previous week of (16^th August - 23^rd August) = 0.9 mm

Maximum Daily Rainfall: 29.8 mm & Minimum Daily Rainfall: 0.0 mm. 

Region	Average rainfall for last 8 days (mm)	Average temperature for last 8 days (ºC)
		Maximum	Minimum
Northern plains	0.4	34.4	26.2
Eastern hills	0.2	30.2	18.2
Eastern plains	1.1	35.8	25.1
Western hills	1.0	29.2	20.0
Western plains	1.6	32.2	26.7
Southern plains	0.8	33.5	25.3

Region	Average rainfall for last 8 days (mm)	Daily maximum rainfall for last 8 days (mm)	Daily minimum rainfall for last 8 days (mm)
Hydro catchment	1.2	46.2	0.0

Wind: Northwest-westerly winds prevailed in the sea area and around the island last week.

Temperatures: The temperature anomalies were above normal for the Western, Sabaragamuwa provinces and some parts of the Southern, Central, Uva, and North Western provinces of the country driven by the warm SST’s.

Predictions

Rainfall: During the next week (24^th August - 30^th August), light showers (25 mm) are predicted for the Southern, Sabaragamuwa, Northern, and Uva provinces and less rainfall is predicted for the rest of the country.

Temperatures: The temperature will remain above normal for some parts of the Eastern, Uva, Northern, North Central, Southern, and Central provinces during 25^th August - 31^st August.

Teleconnections: A positive Dipole Mode has set in across the Indian Ocean since 8^th of June.

MJO shall near neutral the rainfall during 23^rd August - 1^st September and slightly enhance the rainfall during 2^nd - 6^th September for Sri Lanka.

Seasonal Precipitation: The precipitation forecast for the September-October-November, 2023 season shows above normal precipitation for the country.