Climate Bulletin For Sri Lanka (14 October 2022)

  

Highlights          

 • Heavy rainfall (>145 mm) is predicted for the Western, Southern and Sabaragamuwa provinces, and >100 mm rainfall is expected for the Central, Uva, North Western and Eastern provinces during 12th - 18th October.

 • During the last week, the average daily rainfall over Sri Lanka was 4.2 mm and hydro catchment areas received 3.1 mm on average.

 • From 3rd -9th October, up to 10m/s of north-westerly winds were experienced at 850 mb level over the island. Westerly winds are expected next week.

 • Sea surface temperature around Sri Lanka was near normal to the whole country. Land surface temperature remained near normal.

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Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 12^th October – 18^th October:

Total rainfall by Provinces:   

• >145 mm - Southern, Sabaragamuwa, Western
•  135 mm - Central, Uva
•  115 mm - Eastern, North Western
•   85 mm - North Central
•   65 mm - Northern

From 19^th October – 25^th October:

Total rainfall by Provinces:

• 65 mm - Southern, Sabaragamuwa
• 55 mm - Uva, Central, Western
• 45 mm - Northern, North Western, Eastern
• 35 mm - North Central

MJO based OLR predictions:

For the next 15 days: 

MJO shall moderately suppress the rainfall during 12^th– 26^th October for Sri Lanka.

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: October 10, 2022 

Equatorial sea surface temperatures (SSTs) are below average across most of the Pacific Ocean mid - October. The tropical Pacific atmosphere is consistent with La Niña. A large majority of the models indicate La Niña is favored to continue through Northern Hemisphere winter 2022-23, with a 91% chance in September-November, decreasing to a 54% chance in January-March 2023.

Indian Sea Sate

Sea surface temperature around Sri Lanka was near normal to the whole country. 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: Anuradhapura

Daily Average Rainfall in the Met stations for previous week of (4^th - 11^th October) = 4.2 mm

Rmax: 85.6 mm & Rmin: 0.0 mm.

Region	Average rainfall for the Last 8 days
Northern Plains	4.0 mm
Eastern	7.5 mm
Western	2.5 mm
Southern Plains	0.4 mm

The Hydro Catchment Areas recorded 3.1 mm of average rainfall for the last week

Rmax: 40.5 mm & Rmin: 0.0 mm. 

Wind:

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

Temperature: 

The temperature anomalies were above normal for the southern province, driven by the warm SST’s.

Predictions

Rainfall:

During the next week (12^th - 18^th October) heavy rainfall (>145 mm) is predicted for the Western, Sabaragamuwa and Southern provinces, and >100 mm rainfall is expected for the Central, Uva, North Western and Eastern provinces of the country.

Temperature:

The temperature will remain above normal to the east of the country during 13^th – 19^th October.

Teleconnections:

La Niña is favored to continue through Northern Hemisphere winter 2022-23, with a 91% chance in September-November, decreasing to a 54% chance in January-March 2023.

MJO shall moderately suppress the rainfall during 12^th– 26^th October for Sri Lanka.

Seasonal Precipitation: 

The precipitation forecast for the October-November-December 2022 season shows a higher tendency for below-normal precipitation in the southern half of the country.