Climate Bulletin For Sri Lanka (18 December 2020)

                        Highlights                             

•   The NOAA weekly rainfall forecast predicts Between 17th-23rd  Dec; up to 140 mm rainfall will be experienced by the Northern province

•   Between 10th - 16th Dec: up to 100 mm in Jaffna district on 15th  Dec. 

•   MJO shall significantly suppress the rainfall during 16^th – 30^th over Sri Lanka.

•   From 9th  - 15th Dec: up to 5 km/h Northeasterly winds were experienced the northern of the island.

•   Sea surface temperature was observed above 0.50C to the West of Sri Lanka and neutral to the East

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Monitoring

Rainfall

Weekly Monitoring:

Date	Rainfall
10th December	Up to 50 mm in Ratnapura, Kegalle and Kalutara districts.
11th November	Up to 40 mm in Ratnapura, Kalutara and Galle districts.
12th December	No rainfall.
13th December	No rainfall
14th December	Up to 30 mm in Vavuniya, Anuradhapura, Matale and Polonnaruwa districts.
15th December	Up to 100 mm in Jaffna districts.
16th December	Up to 40 mm in Kegalle districts.

Total Rainfall for the Past Week: 

The RFE 2.0 tool shows Cumulative rainfall by Districts:

 50 – 75 mm: Jaffna, Ratnapura, Kegalle, Galle, Kalutara

 25 – 50 mm: Colombo, Gampaha, Matara, Nuwara Eliya, Kandy, Matale, Polonnaruwa, Vavuniya, Kilinochchi                      

 10 - 25 mm: Mullaitivu, Mannar, Anuradhapura, Puttalam, Kurunegala, Moneragala, Hambantota, Ampara, Badulla

   5 – 10 mm: Batticaloa Trincomalee 

Rainfall excess by Districts:

 25 – 50 mm: Jaffna

Rainfall deficit by Districts:

100 – 200mm: Ampara, Moneragala, Batticaloa

  50 – 100mm: Mullaitivu, Vavuniya, Anuradhapura, Polonnaruwa, Trincomalee, Kurunegala, Matale, Kandy, Nuwara Eliya, Ratnapura, Badulla,  Hambantota

 25 – 50 mm : Kilinochchi, Mannar, Puttalam, Kegalle, Gampaha, Colombo, Kalutara, Galle, Matara 

Monthly Monitoring: 

November is usually the wettest month in Sri Lanka. In Nov 2020, there was a deficit overall which was overcome by the cyclone induced rainfall in the Northern half and the Western Slopes.

During November; Rainfall excess conditions by Districts:

8 mm   : Kurunegala, Puttalam, Badulla, Moneragala, Colombo, Gampaha, Ratnapura

6 mm   : Mullaitivu, Vavuniya, Anuradhapura, Trincomalee, Kegalle, Galle, Matara, Kalutara                

4 mm   : Jaffna, Kilinochchi, Mannar, Matale, Kandy, Nuwara Eliya, Hambantota, Polonnaruwa                

2 mm   : Ampara

 

Rainfall deficit rainfall by Districts:

4 mm   :  Batticaloa 

 Predictions

Rainfall

14-day prediction: 

NOAA NCEP models: 

            From 17^th – 23^rd December:

Total rainfall by Provinces:

140 mm   : Northern

135 mm   : Eastern

105 mm   : North-central

  95 mm   : Central Southern Uva

  85 mm   : North-western, Western, Sabaragamuwa 

From 24^th – 30^th December:

Total rainfall by Provinces:

135 mm  : Northern

 55 mm   : Eastern

 25 mm   : Norther-western, Western 

IRI Model Forecast: 

From 24th – 29th September - Cumulative rainfall by Districts:

 75 mm: Badulla

50 mm: Ampara, Moneragala, Ratnapura, Nuwara Eliya, Kandy, Matale, Polonnaruwa,

                Anuradhapura, Batticaloa, Trincomalee, Vavuniya, Mullaitivu, Kilinochchi, Jaffna

25 mm: Mannar, Puttalam, Kurunegala, Kegalle, Gampaha, Colombo, Kalutara, Galle, Matara,

              Hambantota 

MJO based OLR predictions:

For the next 15 days: 

MJO shall  suppress the rainfall during 9^th – 18^th Dec and severely suppress during 19^th -23^rd Dec over Sri Lanka.

Ocean State (Text Courtesy IRI)

Pacific sea state: December 9, 2020 

Equatorial Eastern Pacific SST reached La Niña threshold in early-December, and the atmospheric variables were either ENSO-neutral or indicative of weak La Niña conditions. 

Indian Ocean State

Sea surface temperature was observed above 0.5 ⁰C to the West of Sri Lanka and neutral to the East.