Climate Bulletin For Sri Lanka (10 May 2024)

Highlights          

 • High likelihood of heavy rainfall (100 -150mm) is predicted for the Western, Sabaragamuwa North Western, Southern Provinces and fairly heavy rainfall (50 - 100mm) is predicted for the rest during 8 - 14 May. 

 • Half of expected rainfall (65mm) was received during 8 Apr - 7 May. Apart from Western region, a big deficit of rainfall was observed during April.

 • Winds at 850mb (1.5 km) were south easterly from 29 Apr - 5 May reaching up to 3 m/s. Winds at 850mb (1.5 km) are predicted easterly from 9 - 15 May reaching up to 2 m/s. 

 • Average land surface temperature was 34.4ºC in the last week with warmer anomalies of +1-3ºC. Sea surface temperature around Sri Lanka was 1.0 - 2.5ºC above normal.

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Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 8^th May - 14^th May: 

Total rainfall by Provinces

• 115 mm - Western, Sabaragamuwa  
• 105 mm - North Western, Southern 
•  95 mm - Central
•  85 mm - Eastern, Uva
•  65 mm - Northern, North Central

From 15^th May - 21^st May: 

Total rainfall by Provinces

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

MJO based OLR predictions:

For the next 15 days: 

MJO shall slightly enhance the rainfall during 8^th - 12^th May, moderately enhance the rainfall during 13^th - 17^th May, and slightly enhance the rainfall during 18^th - 22^nd May for Sri Lanka.

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: May 6, 2024 

The SST Anomalies for the NINO3.4 region show a +1.2 ºC on the week ending 6^th May, 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 for the country in 16^th - 22^nd April 2024.     

Interpretation

Monitoring

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

Daily Average Rainfall in the Met stations for previous week of (1^st May - 8^th May) = 3.0 mm

Maximum Daily Rainfall: 70.0 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	0.9	36.2	27.1
Eastern hills	0.4	30.4	19.7
Eastern plains	2.9	35.7	26.4
Western hills	4.7	31.9	20.4
Western plains	6.1	33.7	26.9
Southern plains	2.7	34.6	26.6

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	3.4	50.0	0.0

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

Temperatures: The temperature anomalies were above normal for the country except some parts of the Northern province driven by the warm SST’s.                                                   

Predictions

Rainfall: During the next week (8^th May - 14^th May), heavy rainfall (100 - 150 mm) is predicted for the Western, Sabaragamuwa North Western, and Southern Provinces and fairly heavy rainfall (50 - 100 mm) is predicted for the rest.

Temperatures: The temperature will remain above normal for some parts of the Northern, North Central, Eastern, and Uva provinces during 9^th - 15^th May.

Teleconnections: MJO shall slightly enhance the rainfall during 8^th - 12^th May, moderately enhance the rainfall during 13^th - 17^th May, and slightly enhance the rainfall during 18^th - 22^nd May for Sri Lanka 

Seasonal Precipitation: The precipitation forecast for the May-June-July, 2024 season shows a 70% or more tendency toward above normal precipitation for the country.