Climate Bulletin For Sri Lanka (4 November 2022)

   

Highlights          

 • Heavy rainfall (≥135mm) is predicted for the Sabaragamuwa, Western, Northern, Southern and Central provinces during 2nd - 8th Nov. During 9th - 15th Nov heavy rainfall (≥ 115mm) is predicted for Eastern, North Central, North Western and Uva provinces.

 • During the last week, the average daily rainfall over Sri Lanka was 10.8 mm & hydro catchment areas received 11.37 mm on average.

 • From 24th  -30th Oct, up to 4m/s of north-westerly winds were experienced at 850 mb level over the island. During 3rd - 9th Nov, north easterly winds are expected to the north and northerly winds are expected to south of the country .

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

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Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 2^nd November– 8^th November:

Total rainfall by Provinces:   

• > 135 mm - Western, Southern, Northern, Sabaragamuwa
•  135 mm - Central
•  125 mm - Eastern, North Central
•  115 mm - North Western, Uva

From 9^th November– 10^th November:

Total rainfall by Provinces:

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

MJO based OLR predictions:

For the next 15 days: 

MJO shall slightly suppress the rainfall during 2^nd– 6^th November and slightly increase the rainfall during 7^th – 16^th November for Sri Lanka.

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: October 31, 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 during 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 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 very heavy rainfall over the following area: Kegalle

Daily Average Rainfall in the Met stations for previous week of (25^th October – 1^stNovember)=10.8 mm

Rmax: 117.6 mm & Rmin: 0.0 mm.

Region	Average rainfall for the Last 8 days
Northern Plains	11.2 mm
Eastern	12.9 mm
Western	10.2 mm
Southern Plains	5.6 mm

The Hydro Catchment Areas recorded 11.37 mm of average rainfall for the last week

Rmax: 74.7 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 Central province and some parts of the North western and Eastern provinces, driven by the warm SST’s.

Predictions

Rainfall:

During the next week (2^nd – 8^th November), above 135 mm rainfall is predicted for the Western, Sabaragamuwa, Northern, Southern and Central provinces; and heavy (≥ 115mm) rainfall is expected for the rest of the country.

Temperature:

The temperature will remain above normal to the whole country during 3^rd– 9^th November.

Teleconnections:

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

MJO shall slightly suppress the rainfall during 2^nd– 6^th November and slightly increase the rainfall during 7^th – 16^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.