Weekly Hydro-meteorological Report, 15, August 2019

                                                      Highlights                                

                                 

•  The IRI weekly rainfall forecast predicts up to 75 mm of total rainfall in Mullaitivu and Trincomalee districts during 14 - 19 Aug. 
• Between 7 – 13 Aug: up to 140 mm of rainfalls were recorded in Ratnapura district on the 13th. 
• From 6 – 12 Aug: up to 72 km/h, westerly winds were experienced by the northern half of the island. 
• 1 0C above-average sea surface temperature was observed in the seas around Sri Lanka. 

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Monitoring

Rainfall

Weekly Monitoring:  On August 7th, Gampaha, Colombo, Kalutara, Galle, Matara, Kegalle, Ratnapura, Puttalam, Kurunegala, Anuradhapura, Hambantota and Kandy districts received up to 50 mm of rainfall; Vavuniya, Matale, Nuwara Eliya and Monaragala districts up to 30 mm; Mannar, Trincomalee, Polonnaruwa, Badulla and Ampara districts up to 20 mm.  On the 8th, Galle district received up to 30 mm of rainfall; and Kalutara district up to 20 mm. On the 9th, Galle district received up to 60 mm of rainfall; Colombo, Ratnapura, Matara, Hambantota and Gampaha districts up to 50 mm; Puttalam, Kurunegala, Kegalle and Kalutara districts up to 30 mm; and Matale, Kandy, Nuwara Eliya and Monaragala districts up to 20 mm. On the 10th, Jaffna, Kalutara, Galle, Ratnapura, Nuwara Eliya, Badulla and Monaragala districts received up to 30 mm of rainfall; and Kilinochchi, Ampara and Matara districts up to 20 mm On the 11th, Nuwara Eliya and Kandy districts received up to 30 mm of rainfall; and Badulla, Monaragala, Galle, Matara, Hambantota and Ratnapura districts up to 20 mm. On the 12th, Colombo, Ampara and Monaragala districts received up to 5 mm of rainfall. On the 13th Ratnapura district received up to 140 mm of rainfall; Kegalle and Nuwara Eliya districts up to 90 mm; Kalutara, Galle and Kandy districts up to 60 mm; Gampaha, Colombo, Matara, Hambantota, Badulla and Monaragala districts up to 30 mm; Kurunegala and Matale districts up to 30 mm; and Mullaitivu, Polonnaruwa, Batticaloa and Ampara districts up to 20 mm.

Total Rainfall for the Past Week: The RFE 2.0 tool shows total up to 100-150 mm in Gampaha, Kegalle, Kalutara, Galle, Matara, Ratnapura and Nuwara Eliya districts; up to 75-100 mm in Colombo, Kurunegala, Kandy, Badulla, Monaragala and Hambantota districts; and up to 50-75 mm in Puttalam district. Above-average rainfall up to 100-200 mm in Ratnapura and Nuwara Eliya districts; and up to 50-75 mm in Puttalam, Kurunegala, Kandy, Kegalle, Gampaha, Colombo, Kalutara, Badulla, Hambantota, Matara and Galle districts. 

Monthly Monitoring: During July – Above average rainfall conditions up to 60 mm were experienced by Puttalam, Kurunegala. Kandy, Nuwara Eliya, Badulla, Monaragala, Ampara and Hambantota districts. Below-average rainfall conditions up to 60 mm were experienced by Jaffna, Kilinochchi, Mullaitivu, Mannar, Vavuniya, Matale, Gampaha, Colombo, Kalutara, Galle and Batticaloa districts. The CPC Unified Precipitation Analysis tool shows up to 200 mm of total rainfall in Nuwara Eliya, Badulla and Ratnapura districts; up to 150 mm in Kalutara, Galle, Matara, Kegalle, Kandy and Monaragala districts; up to 100 mm in Puttalam, Kurunegala, Matale and Ampara districts; and up to 75 mm in Gampaha and Trincomalee districts. 

Predictions

Rainfall

14-day prediction: 

NOAA NCEP models: 

From 14th – 20th Aug: Total rainfall up to 25 mm on Jaffna, Kilinochchi, Colombo, Gampaha, Kegalle, Ratnapura, Nuwara Eliya, and Matara districts.

From 21st – 27th Aug: Total rainfall up to 55 mm in Colombo, Kegalle, Ratnapura, Badulla, Monaragala and Hambantota districts; and up to 35-45 mm in Gampaha, Kandy, Nuwara Eliya and Ampara districts. 

IMD NCMWRF Forecast:

16^th Aug: Not Available

17^th Aug: Not Available

IRI Model Forecast: 

From 14th – 19th Aug: Total rainfall up to 75 mm is expected in Mullaitivu and Trincomalee districts; and up to 50 mm in Jaffna, Kilinochchi, Mannar, Vavuniya, Anuradhapura, Polonnaruwa, Batticaloa, Ampara, Kegalle, Gampaha, Colombo, Kalutara, Galle, Ratnapura and Kegalle districts

MJO based OLR predictions:
For the next 15 days: MJO shall not have an impact on the rainfall in Sri Lanka.

Ocean State (Text Courtesy IRI)

Pacific sea state: August 8, 2019

The weak El Niño of 2018-19 has ended. SSTs in the east-central Pacific declined to ENSO-neutral levels during July, and have remained neutral to present. Temperature anomalies of subsurface waters have been near-average. Patterns in most atmospheric variables also are showing ENSO-neutral conditions. Collective model forecasts favor ENSO-neutral through autumn and winter, but with higher chances for El Niño than La Niña. The official CPC/IRI outlook, no longer carrying an El Niño advisory, generally agrees with the model forecasts through winter. 

Indian Ocean State

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