Climate Bulletin For Sri Lanka (28 October 2022)

  

Highlights          

 • Fairly heavy rainfall is predicted for the Western, Southern, Sabaragamuwa,  North Central and Central provinces during 26th Oct - 1st Nov. During 2nd - 8th Nov heavy rainfall (> 100mm) is predicted for Sabaragamuwa, Southern and Western provinces.

 • Southwest of SL experienced very heavy rainfall (<250 mm) during the last week. The average daily rainfall over Sri Lanka was 13.2 mm & hydro catchment areas received 24.5 mm on average.

 • From 17th  -23rd Oct, up to 8m/s of north-westerly winds were experienced at 850 mb level over the island. During 27th Oct - 2nd Nov, north easterlies are expected to the north and north westerlies are expected to south of the country

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

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Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 26^th October – 1^st November:

Total rainfall by Provinces:   

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

From 2^nd November– 8^th November:

Total rainfall by Provinces:

• 135 mm - Sabaragamuwa
• 125 mm - Southern, Western
•  95 mm - Central
•  85 mm - North Western, Uva, Northern
•  75 mm - Eastern, North Central

MJO based OLR predictions:

For the next 15 days: 

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

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: October 24, 2022 

Equatorial sea surface temperatures (SSTs) are below average across most of the Pacific Ocean late - October. The tropical Pacific atmosphere is consistent with La Niña. A large majority of the models indicate 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.

Indian Sea Sate

Sea surface temperature around Sri Lanka was above 0.5℃ to the North of the 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 very heavy rainfall over the following area: Galle

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

Rmax: 169.7 mm & Rmin: 0.0 mm.

Region	Average rainfall for the Last 8 days
Northern Plains	11.8 mm
Eastern	7.2 mm
Western	22.8 mm
Southern Plains	0.8 mm

The Hydro Catchment Areas recorded 24.5 mm of average rainfall for the last week

Rmax: 105.3 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 below normal for the North Western, North Central provinces and some parts of the Western and Eastern provinces, driven by the warm SST’s.

Predictions

Rainfall:

During the next week (26^th October – 1^st 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.

Temperature:

The temperature will remain above normal to the whole country during 27^th October– 2^nd 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 26^th– 30^th October and slightly suppress the rainfall during 31^st – 9^th November 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.