Climate Bulletin For Sri Lanka (23 October 2020)

              Highlights                             

  •  The NOAA weekly rainfall forecast predicts up to 85 mm in Ratnapura, Kegalle and Colombo districts during 29th Oct - 4th Nov.

  •  Between 14th - 20th Oct up to 30 mm in Trincomalee and Anuradhapura districts. However, the rainfall deficits for the last two weeks in Sri Lanka.

  •  MJO shall severely suppress during 21^st– 30^th Oct and significantly suppress during 31^th Oct – 4^th Nov which is leading to dry conditions. La Nina type Eastern Equatorial Pacific could be the cause of the dry conditions

•  From 7th - 13th Oct: up to 15 km/h  northwesterly winds were experienced by the entire island.

•  0.5 0C 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
14th October	Up to 20 mm in Nuwara Eliya and Kandy districts.
15th October	Up to 15 mm in Colombo, Gampaha, Kalutara and Galle districts.
16th October	No rainfall.
17th October	Up to 30 mm in Trincomalee and Anuradhapura districts.
18th October	Up to 20 mm in Batticaloa district.
19th October	Up to 5 mm in Galle, Matara, Hambantota, Moneragala, Batticaloa, Polonnaruwa, Trincomalee, Mullaitivu, Vavuniya and Mannar districts.
20th October	Up to 10 mm in Mullaitivu district.

Total Rainfall for the Past Week: 

The RFE 2.0 tool shows total up to 25 – 50 mm in Trincomalee and Batticaloa districts; up to 10 – 25 mm in Jaffna, Kilinochchi, Mullaitivu, Vavuniya, Mannar, Anuradhapura, Polonnaruwa, Kurunegala, Ampara, Badulla, Moneragala, Matale, Kandy, Nuwara Eliya, Gampaha, Kegalle, Colombo, Kalutara, Ratnapura, Galle and Matara districts; and up to 5 – 10 mm in Puttalam and Hambantota districts. 

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

 

Monthly Monitoring: 

During September – Above average rainfall conditions up to 12 mm in Badulla and Moneragala districts; up to 8 mm in Mannar district; up to 5 mm in Ampara, Polonnaruwa, Batticaloa, Trincomalee, Anuradhapura, Kilinochchi, Mullaitivu, Vavuniya and Jaffna districts; up to 4 mm in Puttalam, Kurunegala, Gampaha, Matale, Kandy, Nuwara Eliya, Ratnapura and Hambantota districts; and up to 2 mm in Colombo, Kalutara, Galle, Matara and Kegalle districts. 

 Predictions

Rainfall

14-day prediction: 

NOAA NCEP models: 

From 22^nd October – 28^th October: Total rainfall up to 65 mm in Ratnapura, Colombo, Galle and Kegalle districts; up to 55 mm in Matara, Nuwara Eliya and Gampaha districts; up to 45 mm in Kandy and Kurunegala districts; up to 35 mm in Hambantota, Moneragala, Badulla and Matale districts; up to 25 mm in Polonnaruwa, Puttalam and Ampara districts; and up to 15 mm in Batticaloa, Trincomalee and Anuradhapura districts. 

From 29^th October – 4^th November: Total rainfall up to 85 mm in Ratnapura, Kegalle and Colombo districts; up to 75 mm in Galle and Gampaha districts; up to 65 mm in Matara, Nuwara Eliya, Kandy and Kurunegala districts; up to 55 mm in Hambantota, Moneragala, Badulla and Puttalam districts; up to 45 mm in Matale district; up to 35 mm in Ampara, Polonnaruwa and Anuradhapura districts; up to 25 mm in Batticaloa and Trincomalee districts; and up to 15 mm in Vavuniya, Mannar and Mullaitivu districts.

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 severely suppress during 21^st– 30^th Oct and significantly suppress during 31^th Oct – 4^th Nov.

Ocean State (Text Courtesy IRI)

Pacific sea state: October 7, 2020 

Equatorial Eastern Pacific SST decreased to near the La Niña threshold in early -October, and the atmospheric variables were either ENSO-neutral or indicative of weak La Niña conditions. The average of the forecasts of many models just short of the borderline of weak La Niña SST conditions through fall, becoming slightly weaker beginning in early winter. The official CPC/IRI outlook is somewhat similar to these model forecasts, calling for a likely continuation of ENSO-neutral in summer, with approximately equal chances of ENSO-neutral or La Niña for fall and winter. 

Indian Ocean State

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