Climate Bulletin For Sri Lanka (11 December 2020)

                        Highlights                             

•   The NOAA weekly rainfall forecast predicts Between 17th-23rd  Dec: very high rainfall over the Northern, North-central and Eastern Provinces.

•   In less than a week after Cyclone Nivar swept past Tamil Nadu and Andhra Pradesh, another cyclone started to brew over the Bay of Bengal 30^th Nov; Burevi was less ferocious than expected in Sri Lanka.

•   Between 3rd - 9th Dec: up to 150 mm in Gampaha district on 8th  Dec.

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

•   From  2nd  - 8st Dec: up to 5 km/h distributed winds were experienced the entire island.

•   0.50C above-average sea surface temperature was observed in the seas around Sri Lanka.

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Monitoring

Rainfall

Weekly Monitoring:

Date	Rainfall
3rd December	Up to 50 mm in Jaffna district.
4th November	Up to 60 mm in Jaffna district.
5th December	Up to 50 mm in Anuradhapura, Vavuniya and Jaffna districts.
6th December	up to 30 mm in Jaffna district.
7th December	Up to 50 mm in Badulla and Moneragala districts.
8th December	Up to 150 mm in Gampaha and Kurunegala districts.
9th December	No rainfall.

Total Rainfall for the Past Week: 

The RFE 2.0 tool shows total up to 150 – 200 mm in Jaffna and Gampaha districts; up to 100 – 150 mm in Colombo, Kegalle and Mannar districts; up to 75 - 100 mm in Kilinochchi, Mullaitivu, Vavuniya, Anuradhapura, Puttalam, Kurunegala, Kalutara, Ratnapura and Badulla districts; up to 50 – 75 mm in Matale, Kandy, Nuwara Eliya, Moneragala and Trincomalee districts; up to 25 -50 mm Polonnaruwa, Ampara, Batticaloa, Galle and Matara districts; up to 10 – 25 mm in Hambantota district.

Above rainfall average up to 100 – 200 mm in Jaffna, Gampaha, Colombo and Kurunegala districts; up to 50 – 100 mm in Mannar, Anuradhapura, Ratnapura, Kurunegala and Puttalam districts; up to 25 – 50 mm in Kilinochchi, Vavuniya, Mullaitivu, Trincomalee, Kandy, Badulla and Moneragala districts; up to 10 – 25 mm Kalutara, Nuwara Eliya and Matale districts;  Below rainfall average up to 50 – 100 mm in Polonnaruwa district; up to 25 – 50 mm in Batticaloa, Galle, Matara and Hambantota districts and 10 – 25 mm Ampara district.   

          

Monthly Monitoring: 

Overall, November had been wettest as usual. However, as November is the wettest month in Sri Lanka, the rainfall was high. During November; Above average rainfall conditions up to 8 mm in Kurunegala, Puttalam, Badulla, Moneragala, Colombo, Gampaha and Ratnapura districts; up to 6 mm in Mullaitivu, Vavuniya, Anuradhapura, Trincomalee, Kegalla, Galla, Matara, and Kalutara districts; up to 4 mm in Jaffna, Kilinochchi, Mannar, Matale, Kandy, Nuwara Eliya, Hambantota and Polonnaruwa districts; up to 2 mm in Ampara district and Below average rainfall up to 4 mm in Batticaloa district. 

 Predictions

Rainfall

14-day prediction: 

NOAA NCEP models: 

From 10^th – 16^th December: Total rainfall up to 105 mm in Northern province; up to 65 mm in Eastern province; up to 55 mm in Northcentral province and up to 25 mm in Southern, Northwestern, Sabaragamuwa and Western provinces.

From 17^th – 23^rd December: Total rainfall up to 140 mm in Northern, North-central and Eastern provinces; up to 105 mm in Northwestern, Central and Uva provinces; up to 95 mm in Sabaragamuwa and Western provinces and up to 75 mm in Southern province.

IRI Model Forecast: 

From 24^th – 29^th September: Total rainfall up to 75 mm in Badulla district; up to 50 mm in Ampara, Moneragala, Ratnapura, Nuwara Eliya, Kandy, Matale, Polonnaruwa, Anuradhapura, Batticaloa, Trincomalee, Vavuniya, Mullaitivu, Kilinochchi and Jaffna districts; and up to 25 mm in Mannar, Puttalam, Kurunegala, Kegalle, Gampaha, Colombo, Kalutara, Galle, Matara and Hambantota districts. 

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 2, 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

0.5 ⁰C above-average sea surface temperature was observed in the seas around Sri Lanka.