Climate Bulletin For Sri Lanka (30 August 2024)

   

Highlights   

       

 •   During 28 Aug – 3 Sep, high likelihood of moderate rainfall (25 - 50 mm) is predicted for the Eastern, North Central, North Western and Northern provinces and Light to Moderate rainfall (12.5 – 25 mm) is predicted for the Sabaragamuwa, Central, Western and Southern provinces and Light Showers (≤12.5 mm) is predicted for the Uva province.

 •    On total, 140 mm was received in SL and rainfall was concentrated in the Western plains (49.8 mm) for last 8 days. On total, 93.4 mm was received in the hydro catchments in SL; Victoria received the highest daily rainfall (18.5 mm) for last 8 days. Highest daily rainfall was in Mattala on 22 Aug (17.7 mm).

 •    From 20 Aug - 28 Aug, winds at 850mb (1.5km) were westerly, reaching up to 10 m/s.  From 28 Aug - 4 Sep, winds are predicted to be westerly, reaching up to 10 m/s.  

 •    Average land surface temperature was 31.0ºC in the last week with warmer and cooler anomalies from seasonal average of 1-3ºC. Eastern plains was warmest followed by Northern, Southern and Western plains. Sea surface temperature around Sri Lanka was 1.0°C above average from 6 Aug to 12 Aug 2024.

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Monitoring

Rainfall: During the last two weeks, there has been very heavy rainfall over the following area: Palugaswewa Estate ( Puttlam )

Total Rainfall in the Met stations for the previous week of (22-28 Aug)=140 mm

Maximum Daily Rainfall: 17.7 mm & Minimum Daily Rainfall: 0.0 mm.

Region	Total rainfall for 22 - 28 Aug (mm)	Average temperature for 22 - 28 Aug (ºC)
		Maximum	Minimum
Northern plains	27.1	32.4	26.2
Eastern hills	0.3	29.2	19.3
Eastern plains	26.5	33.6	25.1
Western hills	11.2	28.0	20.2
Western plains	49.8	31.1	26.1
Southern plains	24.6	31.7	25.5

Region	Total rainfall for 8 - 14 Aug (mm)	Daily maximum rainfall for 22 - 28 Aug (mm)	Daily minimum rainfall for 22 - 28 Aug (mm)
All SL	140	17.7	0.0
Hydro catchment	93.4	18.5	0.0

Wind: Westerly winds prevailed in the sea area and around the island last week.

Temperatures: The temperature anomalies were above normal for some parts of the Uva, Eastern and Sabaragamuwa province and below normal for some parts of the Eastern province for Sri Lanka driven by the warm SSTs.

Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 28^th August - 3^rd September:
Total rainfall by Provinces

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

From 4^th September - 10^th September:  

Total rainfall by Provinces

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

MJO based OLR predictions:

For the next 15 days: 

MJO shall near neutral the rainfall during 28^th August – 11^th September for Sri Lanka.

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: August 26, 2024 

ENSO-neutral conditions are present. Equatorial sea surface temperatures (SSTs) are above average in the western Pacific and near-to-below-average in the eastern Pacific Ocean. ENSO-neutral is expected to continue for the next several months, with La Niña favored to emerge during September-November (66% chance) and persist through the Northern Hemisphere winter 2024-25 (74% chance during November-January).

Indian Sea Sate

Sea surface temperature around Sri Lanka was 1.0°C above average from 6 Aug to 12 Aug 2024.

Interpretation

Monitoring

Rainfall: For August 2024, we had double then the average rainfall. This rise was driven by random and heavy cloud cover over the northern hemisphere due to the tropical convergence zone’s latitude of around 10-15֯ N. The Sri Lanka dome happened, decrease temperature around Sri Lanka and possible rainfall. 

Wind: The wind was flowing North West and quite high.

              

Predictions

Rainfall: During the next week (28 Aug - 3 Sep), moderate rainfall (25 - 50 mm) is predicted for the Eastern, North Central, North Western and Northern provinces and Light to Moderate rainfall (12.5 – 25 mm) is predicted for the Sabaragamuwa, Central, Western and Southern provinces and Light Showers (≤12.5 mm) is predicted for the Uva province.

Temperatures: The temperature will remain above normal for the Northern, Eastern, Southern and Uva provinces during 29 August - 4 September.

Teleconnections: MJO shall near neutral the rainfall during 28th August – 11th September for Sri Lanka.

Seasonal Precipitation: The precipitation forecast for the September-October-November, 2024 season shows a 40% or more tendency toward normal precipitation for the country.