Climate Bulletin for Sri Lanka (21 May 2020)

                                                      Highlights                             

•        The NOAA weekly rainfall forecast predicts up to 50 mm of total rainfall in Gampaha, Colombo, Kalutara, Galle, Matara and Ratnapura districts during 13- 19 May.

•        Between 13- 19 May: up to 100 mm of rainfall was recorded in Monaragala and Galle districts on 14th and 15th.

•        From 12 May -  18 May: up to 18 km/h, northwesterly winds were experienced by the southern regions of the island.

•        1 0C above-average sea the surface temperature was observed in the seas around Sri Lanka.

•         MJO shall enhance the rainfall within the next five days and shall suppress gradually in the next 10 days

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Monitoring

Rainfall

Weekly Monitoring:

Date	Rainfall
13th April	Up to 50 mm in Anuradhapura, Vavunia, Polonnaruwa, Kurunegala and Monaragala districts; up to 40 mm in Matale, Ratnapura and Gampaha districts; and up to 30 mm in Mannar, Ampara, Hambantota and Matara districts.
14th   April	Up to 100 mm in Monaragala district; up to 90 mm in Ampara district; up to 50 mm in Ratnapura district; up to 40 mm in Kalutara, Matara and Hambantota districts; and up to 30 mm in Anuradhapura and Vavuniya districts.
15th May	Up to 100 mm in Galle district; up to 90 mm in Kalutara, Anuradhapura and Vavuniya districts; up to 80 mm in Polonnaruwa, Trincomalee and Batticaloa districts, up to 70 mm in Matara and Ampara districts; up to 60 mm in Colombo and Ratnapura districts; up to 50 mm in Monaragala district; up to 40 mm in Gampaha, Kegalle, Kurunegala and Hambantota districts; and up to 30 mm in Mullaitivu, Puttalam, Kandy, Matale and Nuwara Eliya districts.
16th May	Up to 30 mm in all parts of the island.
17th May	Up to 60 mm in Kurunegala district; up to 50 mm in Trincomalee, Matale and Gampaha districts; up to 40 mm Anuradhapura, Polonnaruwa, Kegalle and Batticaloa districts; and up to 30 mm in Mannar, Vavuniya, Kalutara, Galle, Kandy, Ampara and Ratnapura districts.
18th May	Up to 30 mm in Ratnapura, Kalutara, Galle and Matara districts; and up to 20 mm in Nuwara Eliya, Anuradhapura, Vavuniya, Trincomalee, Mannar, Puttalam, Kalutara, and Kandy districts.
19th May	Up to 10 mm in Gampaha, Colombo, Kalutara, Galle, Matara, Kegalle, Nuwara Eliya, Ratnapura, Puttalam, Kurunegala, Kandy and Hambantota districts; and up to 5 mm in Monaragala, Badulla and Matale districts.

Total Rainfall for the Past Week: 
The RFE 2.0 tool shows total up to 100-150 mm in Anuradhapura, Ratnapura, Vavuniya, Trincomalee, Polonnaruwa, Matale, Kalutara, Galle, Matara, Monaragala, Ampara, Gampaha and Batticaloa districts; up to 75-100 mm in Mullaitivu, Kurunegala, Colombo, Nuwara Eliya, Kandy, Badulla, and Hambantota, districts; and up to 50-75 mm in Jaffna, Kilinochchi and Puttalam districts. 
Above-average rainfall up to 100-200 mm in Anuradhapura, Vavuniya, Polonnaruwa and Trincomalee districts, up to 50-100 mm in Mullaitivu, Mannar, Puttalam, Kurunegala, Gampaha, Kalutara, Galle, Matara, Hambantota, Ratnapura, Badulla, Monaragala, Ampara, Batticaloa, Matale and Kandy districts; up to 25-50 mm in Kilinochchi and Colombo districts; up to 10-25 mm is shown in Jaffna district. 

Monthly Monitoring: 
During April – Above average rainfall conditions up to 360 mm were experienced by Ratnapura, Badulla and Monaragala districts; up to 240 mm in Anuradhapura, Kegalle, Kandy and Matara districts; and up to 120 mm in Vavuniya, Matara, Nuwara Eliya, Colombo, Kalutara, Galle and Hambantota. Below-average rainfall conditions up to 240 mm were experienced by Jaffna, Kilinochchi, Mullaitivu and Gampaha districts; and up to 120 mm in Badulla, Polonnaruwa and Trincomalee districts. The CPC Unified Precipitation Analysis tool shows up to 750 mm of total rainfall in Kegalle, Ratnapura and Monaragala districts; and up to 500 mm in Anuradhapura, Kurunegala, Matale, Kandy, Nuwara Eliya, Colombo, Kalutara, Colombo, Galle and Matara districts.

 Predictions

Rainfall

14-day prediction: 

NOAA NCEP models: 
From 21st - 27th May: Total rainfall up to 115 mm in Galle, Matara and Ratnapura districts; up to 105 mm in Kegalle district; up to 95 mm in Colombo and Nuwara Eliya and Badulla districts; up to 85 mm in Monaragala and Hambantota districts; up to 75 mm in Kandy district; and up to 65 mm in Matale and Kurunegala districts.

From 28th – 3rd May: Total rainfall up to 125 mm in Matara and Galle districts; up to 115 in Ratnapura district; up to 105 mm in Kegalle district; up to 95 mm in Hambantota and Colombo districts; up to 85 mm in Nuwara Eliya, Badulla and Monaragala districts; up to 75 mm in Kandy and Matale districts; and up to 65 mm in Anuradhapura, Polonnaruwa, Trincomalee, Vavuniya, Mannar, Mullaitivu, Kilinochchi and Jaffna districts. 

IRI Model Forecast: 
From 20^th – 25^th May: Total rainfall up to 50 mm in Gampaha, Colombo, Kalutara, Galle, Matara and Ratnapura districts; and up to 25 mm in the other parts of the island. 

MJO based OLR predictions:
For the next 15 days: 
MJO shall enhance the rainfall within the next five days and shall suppress gradually in the next 10 days. 

Ocean State (Text Courtesy IRI)

Pacific sea state: May 13, 2020
SSTs in the east-central Pacific were near above average in mid-May, and many of the atmospheric variables were mainly neutral. Most model forecasts favor neutral SST conditions continuing into summer, becoming below-average but not necessarily into La Nina territory by fall. The official CPC/IRI outlook is consistent with these model forecasts, calling for continuation of ENSO-neutral through fall.

Indian Ocean State
1 ⁰C above-average sea surface temperature was observed in the seas around Sri Lanka.