Climate Bulletin For Sri Lanka (30 October 2020)

              Highlights                             

  •   The NOAA weekly rainfall forecast predicts  up to 65 mm rainfall will be experienced by the southwest of the island from 5th-11th Nov.

  •   Between 21st - 27th Oct: up to 160 mm in Moneragala, Badulla, and Ratnapura districts on 27th Oct.

  •   MJO shall significantly suppress during 28^th Oct – 6^th Nov and slightly suppress during 7^th – 11^th Nov.which is leading to dry conditions. La Nina type Eastern Equatorial Pacific could be the cause of the dry conditions

•   From 21st - 27th Oct:up to 10 km/h  northwesterly winds were experienced by the southern half of the island.

•  Less than 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
21st October	Up to 10 mm in Jaffna district.
22nd October	Up to 10 mm in Jaffna district
23rd October	No rainfall.
24th October	Up to 90 mm in Moneragala and Ampara districts.
25th October	Up to 50 mm in Vavuniya and Anuradhapura districts.
26th October	Up to 40 mm in Anuradhapura, Polonnaruwa, Trincomalee, Moneragala, Badulla, and Ratnapura districts.
27th October	Up to 160 mm in Moneragala, Badulla, and Ratnapura districts.

Total Rainfall for the Past Week: 

The RFE 2.0 tool shows total up to 150 – 200 mm in Moneragala, Badulla, Ratnapura and Ampara districts; up to 100 – 150 mm in Vavuniya and Anuradhapura districts; up to 75 -100 mm in Nuwara Eliya, and Polonnaruwa districts; up to 50 – 75 mm in Mannar, Mullaitivu, Trincomalee, Batticaloa, Matale, Kandy, Hambantota and Kurunegala; up to 25 – 50 mm in Gampaha, Kurunegala and Puttalam districts; up to 10 – 25 mm in Matara, Galle, Kalutara, Colombo and Jaffna districts; and up to 5 – 10 mm in Kilinochchi district. 

Above rainfall average up to 50 – 100 mm in Moneragala, Badulla, Ratnapura and Ampara districts; up to 25 – 50 mm in Nuwara Eliya, Anuradhapura and Vavuniya districts; Below rainfall average up to 50 – 100 mm in Galle, Matara, Kalutara, Colombo, Gampaha, Kegalle, Kandy, Matale, Kurunegala, Puttalam, Batticaloa, Puttalam, Trincomalee, Mannar, Mullaitivu, Kilinochchi and Jaffna; and up to 25 – 50 mm in Hambantota 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 29^th October – 4^th November: Total rainfall up to 55 mm in   Galle, Ratnapura, Kegalle and Colombo districts; up to 45 mm in Matara, Nuwara Eliya and Gampaha districts; up to 35 mm in Hambantota, Moneragala, Badulla, Puttalam, Kurunegala and Kandy districts; up to 25 mm in Matale, Ampara, Batticaloa, Polonnaruwa, Anuradhapura and Trincomalee districts; and up to 15 mm in Vavuniya, Mullaitivu, and Jaffna districts. 

From 5^th – 11^th November: Total rainfall up to 65 mm in Galle, Ratnapura, Kegalle, Gampaha and Colombo districts; up to 55 mm Nuwara Eliya, Kurunegala, Kandy and Puttalam districts; up to 45 mm in Matara and Matale districts; up to 35 mm in Hambantota, Moneragala, Ampara, Badulla, Batticaloa, Polonnaruwa, Anuradhapura, Trincomalee, Vavuniya, Kilinochchi, Mullaitivu and Jaffna districts; and 25 mm in Mannar district. 

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 significantly suppress during 28^th oct – 6^th Nov and slightly suppress during 7^th – 11^th Nov.

Ocean State (Text Courtesy IRI)

Pacific sea state: October 21, 2020 

Equatorial Eastern Pacific SST decreased to near the La Niña threshold in late-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. 

Indian Ocean State

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