Climate Bulletin For Sri Lanka (12 May 2023)

     

Highlights          

 • Fairly heavy rainfall is predicted for the Sabaragamuwa, Western, Southern, North Western, and Central provinces. Cyclone Mocha can lead to high winds and rainfall in South-west facing mountain slopes during 12th- 15th May.

 • During the last week, average daily rainfall over Sri Lanka was 13.2 mm and  hydro catchment areas received 8.9 mm. The western slopes, hills and eastern hills received above-normal rainfall.

 • From 2nd- 8th May, up to 8 m/s of North westerly winds were at 850 mb level. During 12th- 18th May, up to 8 m/s of Easterly winds are expected at 850 mb. Long-range impact of Cyclone Mocha in Central BoB(engal) will lead to high wind 

 • Sea surface temperature around Sri Lanka was about 0.5 - 1 degree above the seasonal norm. Land surface temperature remained near normal.

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Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 11^th May – 17^th May:

Total rainfall by Provinces:    

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

From 18^th May – 24^th May:

Total rainfall by Provinces:   

• 115 mm - Western
•  95 mm - Sabaragamuwa, Southern, North Western
•  75 mm - Central, Uva
•  55 mm - Northern, North Central, Eastern

MJO based OLR predictions:

For the next 15 days: 

MJO shall slightly suppress the rainfall during 11^th May – 25^th May for Sri Lanka.

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: May 8, 2023 

Equatorial sea surface temperatures (SSTs) are near-to-above average across most of the Pacific Ocean early-May. The tropical Pacific atmosphere is consistent with ENSO-neutral conditions. A large majority of the models indicate ENSO-neutral conditions are expected to continue through the Northern Hemisphere spring, followed by a 62% chance of El Nino developing during May-July 2023.

Indian Sea Sate

Sea surface temperature around Sri Lanka was 0.5ºC above normal to the country except northern half in 18^th – 24^th April, 2023. 

 

Interpretation

Monitoring

Rainfall:

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

Daily Average Rainfall in the Met stations for previous week of (3^rd May – 10^th May) = 13.2 mm

Maximum Daily Rainfall: 171.1 mm & Minimum Daily Rainfall: 0.0 mm. 

Region	Average rainfall for the Last 8 days
Northern Plains	15.3 mm
Eastern	10.7 mm
Western	17.3 mm
Southern Plains	6.6 mm

The Hydro Catchment Areas recorded 8.9 mm of average rainfall for the last week.

Maximum Daily Rainfall: 61.0 mm & Minimum Daily Rainfall: 0.0 mm.

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

Temperature: The temperature anomalies were below normal for Northern, North Central, and North Western provinces and some parts of the Eastern, and Central provinces driven by the warm SST’s.

Predictions

Rainfall:

During the next week (11^th May – 17^th May), fairly heavy rainfall (≥ 65 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, Southern, and Uva provinces during 12^th May – 18^th May.

Teleconnections:

ENSO-neutral conditions are expected to continue through the Northern Hemisphere spring, followed by a 62% chance of El Nino developing during May-July 2023.

MJO shall slightly suppress the rainfall during 11^th May – 25^th May for Sri Lanka.

Seasonal Precipitation: 

The precipitation forecast for the May-June-July, 2023 season shows near normal precipitation for the country.