Climate Bulletin For Sri Lanka (29 July 2022)

  

Highlights          

 • Heavy rainfall is predicted for Jaffna districts; fairly heavy rainfall (50–100 mm) is expected for Sabaragamuwa, Central, and Uva provinces and Galle and Matara districts during 29 Jul - 2 Aug.

 • During the last week, the average daily rainfall over Sri Lanka was 6.7 mm and hydro catchment areas have received 11.6 mm on average.

 • From 18th - 24th July, up to 10 m/s of south-westerly and north-westerly winds were experienced over the island.

 •  Sea surface temperature was above 0.5℃ to the north and East of Sri Lanka. Land surface temperature remained near normal.

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Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 27^th July – 2^nd August: 

Total rainfall by Provinces: 

• >100 mm - Northern
•   95 mm - Southern
•   85 mm - Sabaragamuwa, Central, Uva
•   75 mm - Western, Eastern
•   55 mm - North-central, North-western

From 3^rd August – 9^th August: 

Total rainfall by Provinces: 

• >100 mm - Northern
•   25 mm - Sabaragamuwa, Western, Central
•   15 mm - Eastern, North-central, North-western, Uva, Southern

MJO based OLR predictions:

For the next 15 days: 

MJO shall slightly enhance the rainfall during 27^th July - 5^th August; and near-neutral during 6^th August – 10^th August.

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: July 20, 2022 

Equatorial sea surface temperatures (SSTs) are below average across most of the Pacific Ocean inlate-July. The tropical Pacific Sea surface temperatures show a classical La Niña pattern. The tropical Pacific atmosphere is consistent with La Niña. A large majority of the models indicate, a La Niña is favored to continue through 2022 with the odds for La Niña decreasing into the Northern Hemisphere late summer (July - September 2022) before increasing through the Northern Hemisphere fall and early winter 2022.

Indian Sea Sate

Sea surface temperature around Sri Lanka was above 0.5℃ to the north and East of Sri Lanka. Across the Indian Ocean, a classical negative Indian Ocean Dipole prevails as is typical during a La Niña. 

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 (19^th July - 26^th July) = 6.7 mm

Rmax: 105.3 mm & Rmin: 0.0 mm.

Region	Average rainfall for the Last 8 days
Northern Plains	7.1 mm
Eastern	10.8 mm
Western	4.6 mm
Southern Plains	2.4 mm

The Hydro Catchment Areas recorded 11.6 mm of average rainfall for the last week

Rmax: 90.0 mm & Rmin: 0.0 mm.

Wind:

South-westerly and North-westerly prevailed in the sea area and around the island last week. 

Temperature: 

The temperature anomalies were above normal for Sabaragamuwa province and below normal for the north-central and eastern provinces, driven by the warm SST’s.

Predictions

Rainfall:

During the next week (29^th July - 2^nd August) heavy rainfall is predicted for Jaffna districts and fairly heavy rainfall (50 – 100 mm) is expected for Central, Sabaragamuwa and Uva provinces and Galle and Matara districts. 

Temperature:

The temperature remains above normal in the Northern province during 28^th July – 3^rd August. 

Teleconnections:

La Niña - La Niña is favored to continue through 2022 with the odds for La Niña decreasing into the Northern Hemisphere late summer (July-September 2022) before increasing through the Northern Hemisphere fall and early winter 2022.

MJO shall slightly enhance the rainfall during 27^th July - 5^th August; and near-neutral during 6^th August – 10^th August.

Seasonal Precipitation: 

The precipitation forecast for the August-September-October season shows a higher tendency for below-normal precipitation for the southern half of the country, while the remaining areas are more likely to experience near-normal precipitation.