Climate Bulletin For Sri Lanka (4 December 2020)

                        Highlights                             

•   The NOAA weekly rainfall forecast predicts Between 3rd-9th  Dec: high rainfall over the Eastern Province the drop in rainfall over the rest of the country.

•   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 November 2020. Burevi was less ferocious than expected in Sri Lanka.

•   Between 26thNov - 2nd Dec: up to 180 mm in Kilinochchi district on 2nd  Dec.

•   MJO shall slightly enhance the rainfall during 2^nd – 6^th Dec; neutral during 7^th- 11^th Dec and significantly suppresses during 12^th -16^th Dec over Sri Lanka.

•   From  25th  Nov- 1st Dec: up to 4 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
26th November	Up to 30 mm in Jaffna and Kilinochchi districts.
27th November	Up to 50 mm in Moneragala and Badulla districts.
28th November	Up to 10 mm in Moneragala, Badulla, Nuwara Eliya, Kegalle Ratnapura, Kalutara and Colombo districts.
29th November	up to 30 mm in Ratnapura, Matara and Hambantota districts.
30th November	Up to 30 mm in Galle districts.
1st December	Up to 80 mm in Trincomalee and Batticaloa districts.
2nd December	Up to 180 mm in Kilinochchi district.

Total Rainfall for the Past Week: 

The RFE 2.0 tool shows total up to 200 – 300 mm in Kilinochchi district; up to 150 – 200 mm in Jaffna and Mannar districts; up to 100 -150 mm in Mullaitivu, Vavuniya, Trincomalee and Anuradhapura districts; up to 75 – 100 mm in Polonnaruwa, Batticaloa and Badulla districts; up to 50 -75 mm Puttalam, Matale, Ampara and Moneragala districts; up to 25 – 50 mm in Kurunegala, Kandy, Nuwara Eliya, Hambantota, Matara and Ratnapura districts and  up to 10 – 25 mm in Gampaha, Colombo, Kalutara, Galle and Kegalle districts.

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

 

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 3^rd – 9^th December: Total rainfall up to 105 mm in Eastern provinces; up to 95 mm in Northern, province; up to 85 mm in North central, Northwestern and Western provinces; up to 75 mm in Southern, Sabaragamuwa, and Uva provinces and up to 65 mm in Central province. 

From 10^th – 16^th December: Total rainfall up to 75 mm in Eastern province; up to 55 mm in Northern and Western provinces; up to 45 mm in North central, Southern, Sabaragamuwa and Uva provinces and up to 35 mm in Central and Northwestern provinces.

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 slightly enhance the rainfall during 2^nd – 6^th Dec; neutral during 7^th- 11^th Dec and significantly suppresses during 12^th -16^th Dec over Sri Lanka. 

Ocean State (Text Courtesy IRI)

Pacific sea state: November 25, 2020 

Equatorial Eastern Pacific SST reached La Niña threshold in mid-November 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.