Climate Bulletin For Sri Lanka (12 April 2024)

Highlights          

 • High likelihood of fairly heavy rainfall (50 -100mm) is predicted for the Southern, Sabaragamuwa, Uva, Western, Eastern, Central and North Western provinces and moderate rainfall (≤ 35mm) is predicted for the rest during 9-15 April. 

 • On average, only 3/5 of the expected rainfall was received over the country during 10 Mar - 8 April. Average rainfall for SL was 2.4mm and for the hydro-catchment areas was 3.6mm.

 • Winds at 850mb (1.5 km) were  easterly from 31 Mar - 6 April reaching up to 3 m/s. Winds at 850mb (1.5 km) are predicted easterly from 10 - 16 Apr reaching up to 6 m/s.

 •  Average land surface temperature was 33.8ºC in the last week and warmer anomalies of +1-3ºC were higher in the Western slopes and coast compared to the Eastern and Northern regions. Sea surface temperature around Sri Lanka was 0.5 - 1.5ºC above normal.

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Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 9^th April - 15^th April:  

Total rainfall by Provinces

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

From 16^th April - 22^nd April:  

Total rainfall by Provinces

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

MJO based OLR predictions:

For the next 15 days: 

MJO shall slightly enhance the rainfall during 9^th - 13^th April, near neutral the rainfall during 14^th - 18^th April, and slightly suppress the rainfall during 19^th - 23^rd April for Sri Lanka.

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: April 8, 2024 

The SST Anomalies for the NINO3.4 region show a +1.5 ºC on the week ending 8^th April, and a weak El Nino is sustained. Consensus of models predict a continuation of the El Niño event until May 2024 before weakening thereafter.

Indian Sea Sate

Sea surface temperature around Sri Lanka was 0.5℃ above normal to the country in 19^th - 25^th March 2024.

Interpretation

Monitoring

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

Daily Average Rainfall in the Met stations for previous week of (2^nd April - 9^th April) = 2.4 mm

Maximum Daily Rainfall: 121.7 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	1.0	35.2	26.0
Eastern hills	5.3	29.2	18.0
Eastern plains	0.1	34.5	25.3
Western hills	6.1	31.3	19.6
Western plains	3.7	34.0	26.2
Southern plains	0.2	34.6	25.6

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	3.6	60.0	0.0

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

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

     

Predictions

Rainfall: During the next week (9^th April - 15^th April), fairly heavy rainfall (50 - 100mm) is predicted for the Southern, Sabaragamuwa, Uva, Western, Eastern, Central, and North Western provinces and moderate rainfall (≤ 35mm) is predicted for the rest.

Temperatures: The temperature will remain above normal for some parts of the Northern, North Western, North Central, Uva, and Western provinces during 10^th - 16^th April.

Teleconnections: MJO shall slightly enhance the rainfall during 9^th - 13^th April, near neutral the rainfall during 14^th - 18^th April, and slightly suppress the rainfall during 19^th - 23^rd April for Sri Lanka.

Seasonal Precipitation: The precipitation forecast for the April-May-June, 2024 season shows a 40 - 50% tendency toward above normal precipitation for the country.