Climate Bulletin For Sri Lanka (27 November 2020)

              Highlights                             

 • The NOAA weekly rainfall forecast predicts Between 26th Nov -2nd  Dec: high rainfall over the Eastern Province the drop in rainfall over the rest of the country.

 • Cyclonic circulation: emnants shall weaken as it going inland into Tamil Nadu in the next days.  The impacts on Sri Lanka were heavy rainfall and high wind in the Mullaitivu and Jaffna districts and the surrounding seas

 • Between 19th - 25th Nov: up to 90 mm in Jaffna, Mullaitivu and Vavuniya districts on 24th  Nov.

 • MJO shall slightly enhance the rainfall during 25^th – 29^th Nov and Significantly suppress during 30^th Nov - 9^th Dec over Sri Lanka.

 • From  18th - 24th Nov:up to 8 km/h  Northeasterly winds were experienced by the nothern of the island

 • 0.50C above-average sea surface temperature was observed in the seas around Sri Lanka which shall likely change as the La Nina sets in more fully.

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Monitoring

Rainfall

Weekly Monitoring:

Date	Daily Maximum Rainfall
19th November	Up to 30 mm in Galle, Matara, Ratnapura and Kalutara districts.
20th November	Up to 60 mm in Galle and Matara districts.
21st November	Up to 60 mm in Galle and Kalutara districts.
22nd November	Up to 70 mm in Trincomalee district.
23rd November	Up to 60 mm in Mullaitivu, Kilinochchi and Jaffna districts.
24th November	Up to 90 mm in Jaffna, Mullaitivu and Vavuniya districts.
25th November	Up to 70 mm in Jaffna district.

Total Rainfall for the Past Week: 

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

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

Monthly Monitoring: 

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

 Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 26^th November – 2^nd December: Total rainfall up to 135 mm in Eastern province; up to 125 mm in Northern and North central provinces; up to 95 mm in North western province: up to 85 mm in Central, and Uva provinces; 75 mm in Western and Sabaragamuwa provinces and 55 mm in Southern province.

From 3^rd – 9^th December: Total rainfall up to 95 mm in Eastern province; up to 75 mm in Northern and North central provinces; up to 65 mm in Central, North western, Western, Sabaragamuwa and Uva provinces and up to 55 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 slightly enhance the rainfall during 25^th – 29^th Nov and Significantly suppress during 30^th Nov - 9^th Dec over Sri Lanka.

Ocean State (Text Courtesy IRI)

Pacific sea state: November 18, 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.