Climate Bulletin For Sri Lanka (21 October 2022)

 

Highlights          

 • Heavy rainfall (≥105 mm) is predicted for the Sabaragamuwa, Western, Southern, North western and Central provinces; and fairly heavy rainfall (≥75 mm) is expected for the rest of the country during 19th - 25th October.

 • During the last week, the average daily rainfall over Sri Lanka was 16.6 mm and hydro catchment areas received 18.7 mm on average.

 • From 21st  -27th October, up to 6m/s of north-westerly winds were experienced at 850 mb level over the island. North westerly winds are expected next week.

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

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Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 19^th October – 25^th October:

Total rainfall by Provinces:   

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

From 26^th October – 1^st November:

Total rainfall by Provinces:

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

MJO based OLR predictions:

For the next 15 days: 

MJO shall slightly suppress the rainfall during 19^th– 23^rd October; slightly enhance the rainfall during 24^th – 28^th October and near neutral during 29^th – 2^nd November for Sri Lanka.

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: October 17, 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 (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 and East 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:

Kaluthara

Daily Average Rainfall in the Met stations for previous week of (11^th - 18^th October) = 16.6 mm

Rmax: 168.6 mm & Rmin: 0.0 mm.

Region	Average rainfall for the Last 8 days
Northern Plains	8.7 mm
Eastern	11.9 mm
Western	31.3 mm
Southern Plains	1.7 mm

The Hydro Catchment Areas recorded 18.7 mm of average rainfall for the last week

Rmax: 124.0 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, driven by the warm SST’s.

Predictions

Rainfall:

During the next week (19^th - 25^th October) heavy rainfall (>105 mm) is predicted for the Western, Sabaragamuwa, Southern, North western and Central provinces; and fairly heavy rainfall (≥75 mm) is expected for the rest of the country.

Temperature:

The temperature will remain above normal to the north, north central and east of the country during 21^th – 27^th October.

Teleconnections:

La Niña is favored to continue through 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 19^th– 23^rd October; slightly enhance the rainfall during 24^th – 28^th October and near neutral during 29^th – 2^nd 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.