Climate Bulletin For Sri Lanka (17 May 2024)

Highlights          

 • High likelihood of Extreme rainfall (100 - 150 mm) is predicted for the all over the country during 15 - 21 May. 

 • Only 5/6 of expected rainfall (100mm) was received during 15 April - 14 May. Apart from

Western region, a big deficit of rainfall was observed during April.

 • Winds at 850mb (1.5 km) were north westerly  from 6  - 12 May reaching up to 3 m/s. Winds at 850mb (1.5 km) are predicted north westerly from 16 - 22 May reaching up to 15 m/s.

 • Average land surface temperature was 33.0ºC  in the last week with warmer anomalies of +1-3oC. Sea surface temperature around Sri Lanka was 1.0 - 2.0ºC above the seasonal normal. The temperature has dropped slightly.

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Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 16^th May - 22^nd May: 

Total rainfall by Provinces

• >135 mm - Western, Sabaragamuwa, North Western, Southern,  Central, Uva, North central
• <125 mm - Northern, Eastern

From 23^rd May - 29^th May: 

Total rainfall by Provinces

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

MJO based OLR predictions:

For the next 15 days: 

MJO shall moderately enhance the rainfall during 16^th - 20^th May and slightly enhance the rainfall during 21^th - 30^th May for Sri Lanka.       

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: May 13, 2024 

El Niño is transitioning toward ENSO-neutral. Equatorial sea surface temperatures (SSTs) are above average in the western and central Pacific Ocean, and below-average SSTs are emerging in parts of the eastern Pacific Ocean. La Niña may develop in June-August 2024 (49% chance) or July-September (69% chance)..

Indian Sea Sate

Sea surface temperature around Sri Lanka was 1.0℃ above normal to the Western, Northern, and Southern half of the country in 23^rd - 29^th April 2024  

Interpretation

Monitoring

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

Daily Average Rainfall in the Met stations for previous week of (8^th May - 15^th May) = 12.0 mm

Maximum Daily Rainfall: 154.7 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	11.5	34.6	25.6
Eastern hills	14.2	28.4	19.7
Eastern plains	8.0	34.1	25.4
Western hills	14.8	30.3	20.2
Western plains	15.0	33.1	25.5
Southern plains	9.2	33.9	25.4

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	16.8	68.5	0.0

Wind: North westerly 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, Eastern, and Western provinces driven by the warm SST’s.                                                           

Predictions

Rainfall: During the next week (15^th May - 21^st May), heavy rainfall (100 - 150mm) is predicted for the Western, Sabaragamuwa, North Western, Southern, Central, and Uva Provinces and fairly heavy rainfall (50 - 100 mm) is predicted for the rest.

Temperatures: The temperature will remain below normal for some parts of the Central, Western, North Western, Southern, and Uva provinces during 16^th - 22^nd May.

Teleconnections: MJO shall moderately enhance the rainfall during 16^th - 20^th May and slightly enhance the rainfall during 21^th - 30^th May for Sri Lanka

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