Highlights

Rainfall Prediction: Fairly heavy rainfall (≥55 mm) is predicted for the Western, Sabaragamuwa, Southern, North Central and Central provinces; and moderate rainfall (≥35mm) is expected for the rest of the country during 26thOct – 1st Nov

Monitored Rainfalls: The southwest of Sri Lanka experienced very heavy rainfall (<250mm) last week. The average daily rainfall in Sri Lanka was 13.2mm & hydro catchment areas received 24.5mm on average.

Monitored Wind: From 17th-23rd Oct, up to 8m/s of north-westerly winds were experienced at 850mb level over the island. From 27th Oct – 2nd Nov, northeasterlies are expected to the north, and north westerlies are expected to the South of the country.

Monitored Sea and Land Temperature: Sea surface temperature around Sri Lanka was above normal to the North of the country. The land surface temperature remained near normal.

Climate Bulletin for Sri Lanka (Week of 28 Oct – 04 Nov 2022)

Interpretation

Monitoring

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

Daily Average Rainfall in the Met stations for the previous week of (18th- 25th October) = 13.2 mm

Rmax: 169.7 mm & Rmin: 0.0 mm.

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

Temperatures:  The temperature anomalies were below normal for the North Western, and North Central provinces and some parts of the Western and Eastern provinces, driven by the warm SSTs.

Prediction

Rainfall: During the next week (26th October – 1st November) fairly heavy rainfall (85 mm) is predicted for the Western, Sabaragamuwa, and Southern provinces; and below 55 mm of rainfall is expected for the rest of the country.

Temperatures: The temperature will remain above normal for the whole country from 27th October–2nd November.

Teleconnections: La Niña is favored to continue through the Northern Hemisphere winter (December-February) 2022-23, with a 54% chance for ENSO-neutral in February-April 2023.

MJO shall significantly suppress the rainfall during 26th– 30th October and slightly suppress the rainfall from 31st Oct– 9th Nov for Sri Lanka.

Seasonal Precipitation: The precipitation forecast for the November-December-January 2023 season shows a higher tendency for above-normal precipitation in the north half of 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