Highlights

Rainfall Prediction: NCEP GFS prediction for 11th onwards, the heaviest rainfall in Ratnapura, Galle &Kalutara districts is hazardous. Heavy rainfall above100mm is expected in Sabaragamuwa Western, Southern & Central provinces.

Monitored Rainfalls: During the last week, average daily rainfall over Sri Lanka was 4.4mm and hydro catchment areas have received 9.4mm on average

Monitored  Wind: From 2nd – 8th May, up to 10 m/s westerlies and South-westerlies were experienced over the Island.

Monitored  Temperature: Sea surface temperature was above 0.5℃ to the north and east of Sri Lanka. Land surface Temperature remained near normal during the last week.

Climate Bulletin for Sri Lanka (Week of 13 May – 20 May 2022)
Climate Bulletin for Sri Lanka (Week of 13 May – 20 May 2022)

Interpretation

Monitoring

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

Daily Average Rainfall in the Met stations for previous week of (2nd- 9th May) = 4.4 mm

Rmax: 105 mm & Rmin: 0.0 mm.

The Hydro Catchment Areas recorded 9.4 mm of average rainfall for the last week

Rmax: 98 mm & Rmin: 0 mm.

Wind: Westerly and South-westerly prevailed in the sea area surrounding the island last week.

Temperatures: The temperature anomalies were above normal for the Western, Sabaragamuwa and North-western provinces and neutral for the rest of the country, driven by the warm SST’s.

Prediction

Rainfall: During the next week (13th- 17th May) heavy rainfall (>100 mm) is predicted for the Western, Sabaragamuwa, Southern, and Central provinces. NCEP GFS prediction for 11th onwards, the heaviest rainfall expected in Ratnapura, Galle & Kalutara districts is hazardous

Temperature : The temperature remains slightly below normal in the Central, Uva & Sabaragamuwa provinces and above normal in the Eastern province during 6th- 14th May.

Teleconnections:

La Nina – The SST forecast indicates that La Niña is favored to continue into the Northern Hemisphere summer (June-August 2022). MJO shall neutral during 13th – 15th May, shall moderately suppress the rainfall during 16th – 20th May and severely suppress during 21st – 25th May.

Seasonal Precipitation:

The precipitation forecast for the May-June-July season shows below-normal precipitation for the island, but above-normal precipitation for the Northern province.

Terminology for Rainfall Ranges

Rainfall (During 24 hours of period)
Light ShowersLess than 12.5 mm
Light to ModerateBetween 12.5 mm and 25 mm
ModerateBetween 25 mm and 50 mm
Fairly HeavyBetween 50 mm and 100 mm
HeavyBetween 100 mm and 150 mm
Very HeavyMore than 150 mm