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Friday, November 18, 2022

Climate Bulletin For Sri Lanka (18 November 2022)

     

Highlights          


 • Fairly heavy (≥ 55 mm) rainfall is predicted for the Sabaragamuwa, Southern, Northern, Western, and Central provinces during 16th - 22nd November.
 • During the last week, the average daily rainfall over Sri Lanka was 14.4 mm & hydro catchment areas received 9.4 mm on average and the highest average rainfall (17 mm) was received to the Eastern and Southern plains of the country.
 • From 7th - 13th Nov, up to 6m/s of north-easterly winds were experienced at 850 mb level over the island. During 17th - 23rd Nov, north - westerly winds are expected to the country .
 • Sea surface temperature around Sri Lanka was above normal to the Southern half of the country. Land surface temperature remained near normal.



Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 
From 16th November– 22nd November:
Total rainfall by Provinces:   
  •   85 mm - Southern, Sabaragamuwa
  •   75 mm - Northern, Western
  •   55 mm - Central
  •   25 mm - Eastern, Uva
  • < 25 mm - North Western, North Central
MJO based OLR predictions:
For the next 15 days: 
MJO shall moderately suppress the rainfall during 16th– 25th November and slightly suppress the rainfall during 26th – 30th November for Sri Lanka.

Ocean State (Text Courtesy IRI)
Pacific Sea Sate: November 14, 2022 
Equatorial sea surface temperatures (SSTs) are below average across most of the Pacific Ocean mid - November. 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 transition to ENSO-neutral favored in February-April 2023 (57% chance).

Indian Sea Sate
Sea surface temperature around Sri Lanka was above 0.5℃ to the Southern half of country in 9th November, 2022. 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 areas: Kegalle, Jaffna, and Avissawella

Daily Average Rainfall in the Met stations for previous week of (8th November – 15th November) = 14.4 mm

Rmax: 133.9 mm & Rmin: 0.0 mm.


Region

Average rainfall for the Last 8 days

Northern Plains

14.8 mm

Eastern

17.3 mm

Western

12.5 mm

Southern Plains

17.9 mm


The Hydro Catchment Areas recorded 9.4 mm of average rainfall for the last week
Rmax: 92.9 mm & Rmin: 0.0 mm. 

Wind:
North-easterly 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 Eastern, Eastern and Central provinces, driven by the warm SST’s.

Predictions
Rainfall:
During the next week (16th – 22nd November), fairly heavy (≥ 55 mm) rainfall is predicted for the Southern, Sabaragamuwa, Northern, Western, and Central provinces; and less rainfall is expected for the rest of the country.
Temperature:
The temperature will remain below normal for some parts of the Central and Uva provinces during 17th – 23rd November.
Teleconnections:
La Niña is favored to continue through during the Northern Hemisphere winter (December-February) 2022-23, with a transition to ENSO-neutral favored in February-April 2023 (57% chance).
MJO shall moderately suppress the rainfall during 16th– 25th November and slightly suppress the rainfall during 26th – 30th November for Sri Lanka.

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

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