Highlights

Rainfall Prediction: Fairly heavy rainfall (55 – 75 mm) is predicted for the Sabaragamuwa, Southern, Western, Central provinces and less rainfall is predicted for the rest of the country during 13 – 19 July.

Monitored Rainfall: During the last week, average daily rainfall over Sri Lanka was 2.2 mm and hydro catchment areas received 6.6 mm. Highest average rainfall of 6.2mm/day received in Western region.

Monitored and Predicted Wind: From 4 – 10 Jul, up to 15 m/s of northwest-westerly winds were at 850mb (1.5 km). During 14 – 20 Jul, up to 15 m/s of northwest-westerly winds are expected at 850 mb (1.5 km).

Monitored Sea and Land Temperature: Sea surface temperature around Sri Lanka was 0.25 – 1.5°C above normal. Average maximum land temperature ranged from 29 – 32°C and minimum ranged from 24 -25°C with a drop in the hills.

Climate Bulletin for Sri Lanka (Week of 14 July – 21 July 2023)

Interpretation

Monitoring

Rainfall: During the last two weeks, there had been heavy rainfall over Kegalle, Nuwara Eliya

Daily Average Rainfall in the Met stations for previous week of (5th July – 12th July) = 2.2 mm

Maximum Daily Rainfall: 47.5 mm & Minimum Daily Rainfall: 0.0 mm.

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

Temperatures: The temperature anomalies were near normal for the country driven by the warm SST’s.

Prediction

Rainfall: During the next week (13th July – 19th July), fairly heavy rainfall (≥ 55 mm) is predicted for the Sabaragamuwa, Southern, Western and Central provinces and less rainfall is predicted for the rest of the country.

Temperatures: The temperature will remain above normal for some parts of the Northern, Eastern, Uva, North Central, and Southern provinces and below normal for some parts of the Central province during 14th July – 20th July.

Teleconnections: A positive Dipole Mode has set in across the Indian Ocean since 8th of June.

MJO shall slightly enhance the rainfall during 13th – 27th July for Sri Lanka.

Seasonal Precipitation: The precipitation forecast for the July-August-September, 2023 season shows above normal precipitation for the country.

Terminology for Rainfall Ranges

Rainfall (During 24 hours of the 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