Climate Bulletin For Sri Lanka (26 May 2023)

      

Highlights          

 • Fairly heavy rainfall is predicted for the  Sabaragamuwa, Western, Southern, North Western, Central provinces during 25 - 31 May. Heavy rainfall is predicted for the Western, Sabaragamuwa, Southern, North Western provinces during 1 - 7 June.

 • During the last week, average daily rainfall over Sri Lanka was 2.7 mm and  hydro catchment areas received 2.6 mm.

 • From 16 - 22 May, up to 5 m/s of south westerly winds were at 850 mb (1.5 km). During 26 May - 1 June, up to 10 m/s of westerly winds are expected at 850 mb (1.5 km). 

 • Sea surface temperature around Sri Lanka was 0.5 - 1.5ºC above normal. Average maximum land temperature ranged from 32- 33ºC and average minimum ranged from 23 - 25ºC with a drop in the hills. 

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Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 25^th May – 31^st May:

Total rainfall by Provinces:    

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

From 1^st June – 7^th June:

Total rainfall by Provinces:   

• 125 - Western, Sabaragamuwa
• 115 - Southern
• 105 - North Western
• 95  - Central
• 75  - Uva
• 65  - North Western, Northern
• 55  - Eastern

MJO based OLR predictions:

For the next 15 days: 

MJO shall significantly suppress the rainfall during 24^th – 28^th May, slightly suppress the rainfall during 29^th May – 2^nd June, and slightly increase the rainfall during 3^rd – 7^th June for Sri Lanka.

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: May 22, 2023 

Equatorial sea surface temperatures (SSTs) are near-to-above average across most of the Pacific Ocean mid-May. The tropical Pacific atmosphere is consistent with ENSO-neutral conditions. A large majority of the models indicate a transition from ENSO-neutral conditions in the next couple of months, with a greater than 90% chance of El Niño persisting into the Northern Hemisphere winter.

Indian Sea Sate

Sea surface temperature around Sri Lanka was 0.5º C above normal to the Eastern and Western half of the country in 2nd – 8th May, 2023. 

 

Interpretation

Monitoring

Rainfall:

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

Daily Average Rainfall in the Met stations for previous week of (17^th May – 24^th May) = 2.7 mm

Maximum Daily Rainfall: 46.6 mm & Minimum Daily Rainfall: 0.0 mm. 

Region	Average rainfall for the Last 8 days
Northern Plains	0.5 mm
Eastern	1.1 mm
Western	6.5 mm
Southern Plains	1.9 mm

The Hydro Catchment Areas recorded 2.6 mm of average rainfall for the last week.

Maximum Daily Rainfall: 46.3 mm & Minimum Daily Rainfall: 0.0 mm.

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

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

Predictions

Rainfall:

During the next week (25th May – 31st May), fairly heavy rainfall (≥ 55 mm) is predicted for the Western, Sabaragamuwa, Southern, North Western, and Central provinces and less rainfall is predicted for rest of the country

Temperature:

The temperature will remain above normal for some parts of the Northern, Eastern, North Central, Uva, and Southern provinces during 26th May – 1st June.

Teleconnections:

A transition from ENSO-neutral conditions in the next couple of months, with a greater than 90% chance of El Niño persisting into the Northern Hemisphere winter.

MJO shall significantly suppress the rainfall during 24th – 28th May, slightly suppress the rainfall during 29th May – 2nd June, and slightly increase the rainfall during 3rd – 7th June for Sri Lanka.

Seasonal Precipitation: 

The precipitation forecast for the June-July-August, 2023 season shows above normal precipitation for the country.