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Friday, December 9, 2022

Climate Bulletin For Sri Lanka (9 December 2022)

        

Highlights          


 • Fairly heavy (> 80 mm) rainfall is predicted for the Northern and Eastern provinces and moderately heavy (≥ 45 mm) rainfall is predicted for the rest of the country during 7th - 13th December.
 • During the last week, the average daily rainfall over Sri Lanka was 5.0 mm & hydro catchment areas received 6.9 mm on average and the highest average rainfall (6.8 mm) was received to the Western plains of the country.
 • From 28th Nov - 4th Dec, up to 5m/s of north easterly winds were experienced at 850 mb level over the island. During 8th - 14th Dec, up to 8m/s of north westerly winds are expected to the country.
 • Sea surface temperature around Sri Lanka was above normal to the western, eastern, and southern half of the country. Land surface temperature remained near normal. 



Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 
From 7th December – 13th December:
Total rainfall by Provinces:   
  • 95 mm - Northern
  • 85 mm - Eastern
  • 75 mm - North Central
  • 65 mm - Central
  • 55 mm - Uva, Western, Sabaragamuwa
  • 45 mm - Southern, North Western
From 14th December – 20th December:
Total rainfall by Provinces:   
  • 105 mm - Eastern
  •  95 mm - Northern, Uva, North Central
  •  85 mm - Central, Sabaragamuwa
  •  75 mm - Western, North Western, Southern
MJO based OLR predictions:
For the next 15 days: 
MJO shall slightly increase the rainfall during 7th December – 21st December for Sri Lanka.

Ocean State (Text Courtesy IRI)
Pacific Sea Sate: December 5, 2022 
Equatorial sea surface temperatures (SSTs) are below average across most of the Pacific Ocean early - December. 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 western, eastern, and southern half of the country in 30th 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 heavy rainfall over the following areas: Rathnapura, Kalutara

Daily Average Rainfall in the Met stations for previous week of (29th November – 6th December) =5.0 mm

Rmax: 73.7 mm & Rmin: 0.0 mm.

Region

Average rainfall for the Last 8 days

Northern Plains

4.2 mm

Eastern

5.4 mm

Western

6.8 mm

Southern Plains

1.2 mm


The Hydro Catchment Areas recorded 6.9 mm of average rainfall for the last week

Rmax: 110.0 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 above normal for some parts of the Western, and Sabaragamuwa provinces, driven by the warm SST’s.

Predictions
Rainfall:
During the next week (7th Dec – 13th Dec), fairly heavy (> 80 mm) rainfall is predicted for the Northern and Eastern provinces; and moderately heavy (≥ 45 mm) rainfall is expected for the rest of the country.
Temperature:
The temperature will remain below normal for some parts of the Central, Uva, Sabaragamuwa, Northern, and Eastern provinces during 8th – 14th December.
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 slightly increase the rainfall during 7th December – 21st December for Sri Lanka.

Seasonal Precipitation: 
The precipitation forecast for the December-January-February 2023 season shows a higher tendency for near-normal precipitation to the country.

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