Weekly Hydro-meteorological Report, 22, August 2019

                                                      Highlights                                

                                 

• The IRI weekly rainfall forecast predicts up to 75 mm of total rainfall in Kalutara and Galle districts during 21 - 26 Aug. 
• Between 14 – 19 Aug: up to 100 mm of rainfalls were recorded in Polonnaruwa district on the 16th. 
• From 13 – 19 Aug: up to 54 km/h, northwesterly winds were experienced by the entire 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 14th, Galle, Matara and Hambantota districts received up to 20 mm of rainfall; and Kalutara and Ratnapura districts up to 10 mm.  On the 15th, Kilinochchi, Mannar, Mullaitivu, Puttalam, Kurunegala, Matale and Polonnaruwa districts received up to 5 mm of rainfall. On the 16th, Polonnaruwa district received up to 100 mm of rainfall; Matale and Ampara districts up to 80 mm; Trincomalee, Anuradhapura and Monaragala districts up to 60 mm; Mullaitivu, Mannar, Puttalam and Badulla districts up to 50 mm; and Kandy and Kilinochchi districts up to 20 mm. On the 17th, Kurunegala district received up to 20 mm of rainfall. On the 18th, Vavuniya district received up to 90 mm of rainfall; Kilinochchi, Mullaitivu, Mannar, Anuradhapura and Gampaha districts up to 50 mm; Puttalam, Kurunegala, Trincomalee, Monaragala and Ampara districts up to 30 mm; and Polonnaruwa district up to 20 mm. On the 19th, Batticaloa, Ampara, Badulla, Monaragala and Ratnapura districts received up to 20 mm of rainfall. On the 20th, Ratnapura district received up to 30 mm of rainfall; and Mullaitivu, Vavuniya, Gampaha, Colombo, Monaragala and Hambantota districts up to 20 mm.

Total Rainfall for the Past Week: The RFE 2.0 tool shows total up to 75-100 mm in Polonnaruwa, Matale and Badulla districts; up to 50-75 mm in Anuradhapura, Trincomalee, Ampara and Monaragala districts; and up to 25-50 mm in Jaffna, Kilinochchi, Mullaitivu, Vavuniya, Mannar, Puttalam, Kurunegala, Kandy, Gampaha, Ratnapura and Galle districts. Above-average rainfall up to 50-100 mm in Polonnaruwa districts; and up to 25-50 mm in Vavuniya, Anuradhapura, Matale, Monaragala, Ampara and Batticaloa districts.  Below-average rainfall up to 25-50 mm in Kalutara, Ratnapura and Galle districts; and up to 10-25 mm in Trincomalee, Gampaha, Colombo, Kegalle, Kandy, Nuwara Eliya, Badulla, Matara and Hambantota 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 21st – 27th Aug: Total rainfall up to 55 mm on Jaffna and Kilinochchi, districts; up to 35-45 mm in Mannar, Vavuniya and Trincomalee districts; and up to 25-35 mm in Puttalam, Anuradhapura and Polonnaruwa districts.

From 27th Aug – 3rd Sep: Total rainfall up to 35 mm Ratnapura districts; and up to 15-25 mm in Jaffna, Colombo, Kegalle, Nuwara Eliya, Kandy, Matara and Hambantota districts. 

IMD NCMWRF Forecast:

23^rd Aug: Not Available

^24th Aug: Not Available

IRI Model Forecast: 

From 21st – 26th Aug: Total rainfall up to 75 mm is expected in Kalutara and Galle districts; and up to 50 mm in Jaffna, Kilinochchi, Puttalam, Gampaha, Colombo, Ratnapura, Matara and Kegalle districts. 

MJO based OLR predictions:

For the next 15 days:  MJO shall not have an impact on the rainfall in Sri Lanka in the next 5 days and shall enhance in the following 10 days.  

Ocean State (Text Courtesy IRI)

Pacific sea state: August 19, 2019

The weak El Niño of 2018-19 has ended, as SSTs in the east-central Pacific cooled to ENSO-neutral levels during July. 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.