Weekly Hydro-meteorological Report, 05, September 2019

                                                      Highlights                                

                                 

• The IRI weekly rainfall forecast predicts up to 75 mm of total rainfall in Batticaloa, Ampara and Monaragala districts during 4– 9 Sep

• Between 27 Aug - 3 Sep: up to 175 mm of rainfalls were recorded in Colombo and Ratnapura districts on the 29th.

• From 27 Aug – 2 Sep: up to 36 km/h, westerly winds were experienced by the entire island.

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

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Monitoring

Rainfall

Weekly Monitoring: On August 27^th, Galle and Ratnapura districts received up to 30 mm of rainfall; and Gampaha, Colombo, Kalutara, and Matara districts up to 20 mm.  On the 28^th, Hambantota, Galle and Matara districts received up to 30 mm of rainfall; and Gampaha, Colombo and Kalutara district up to 20 mm. On the 29^th, Colombo and Ratnapura districts received up to 175 mm of rainfall; Gampaha, Kegalle, Kalutara and Galle districts up to 120 mm; Nuwara Eliya and Matara districts up to 90 mm; Anuradhapura, Hambantota, and Monaragala districts up to 50 mm; Jaffna, and Puttalam districts up to 30 mm; and Kilinochchi, Mullaitivu, Mannar, Matale, Kandy, Badulla, and Ampara districts up to 20 mm. On the 30^th, Badulla district received up to 15 mm of rainfall; and Matale, Nuwara Eliya, Ratnapura and Kalutara district up to 10 mm. On the 31^st, Kalutara, Colombo, Gampaha, Kegalle, Ratnapura and Kalutara districts received up to 30 mm of rainfall; and Matale, Galle, Matara, and Hambantota districts up to 20 mm. On September 1^st, Colombo, Monaragala and Hambantota districts received up to 50 mm of rainfall; Gampaha, Kalutara, Galle, Kegalle, Ratnapura and Matara districts up to 30 mm; and Nuwara Eliya and Batticaloa districts up to 20 mm. On the 2^nd, Batticaloa, Kalutara and Galle districts received up to 15 mm of rainfall. On the 3^rd, Gampaha, Colombo, Kegalle districts received up to 15 mm of rainfall.

Total Rainfall for the Past Week: The RFE 2.0 tool shows total up to 200-300 mm in Colombo, Kalutara and Ratnapura districts; up to 150-200 mm in Galle and Kegalle districts; up to 100-150 mm Gampaha, Galle and Matara districts: and up to 75-100 mm Nuwara Eliya and Ratnapura districts. Above average rainfall up to 100-200 mm in Colombo, Kalutara, Ratnapura, Galle and Matara districts; up to 50-100 mm in Gampaha, Nuwara Eliya and Hambantota districts; and up to 25-50 mm in Kegalle, Nuwara Eliya and southern regions of Monaragala districts.  Below-average rainfall up to 10-25 mm in Trincomalee, Anuradhapura, Kurunegala, Matale, Kandy, Badulla, Ampara and central regions of Monaragala district.

Monthly Monitoring: During August – Above average rainfall conditions up to 360 mm were experienced by Gampaha, Colombo, Kalutara, Galle, Matara, Kegalle, and Ratnapura districts; up to 240 mm in Puttalam, Kurunegala, Nuwara Eliya, Anuradhapura, Polonnaruwa, Matale, Monaragala and Hambantota; and up to 120 mm in Jaffna, Kilinochchi, Mullaitivu, Mannat, Vavuniya, Ampara, and Batticaloa. Below-average rainfall conditions up to 180 mm were experienced Trincomalee and most parts of Badulla district. The CPC Unified Precipitation Analysis tool shows up to 750 mm of total rainfall in Ratnapura district; up to 500 mm in Gampaha, Colombo, Kalutara, Galle, Matara, Kegalle, and Nuwara Eliya districts; up to 300 mm in Puttalam, Kurunegala and Hambantota districts; and up to 200 mm in Kandy, Badulla, and Monaragala districts.

Predictions

Rainfall

14-day prediction: 

NOAA NCEP models: 

From 4^th – 10^th Sep: Total rainfall up to 85 mm on Galle, Kegalle, Ratnapura and Gampaha districts; up to 65-75 mm in Matara and Hambantota districts; and up to 55-65 mm in Colombo and Kalutara districts.

From 11^th – 17^th Sep: Total rainfall up to 65 mm Gampaha, Ratnapura, and Kegalle districts; and up to 45-55 mm in Puttalam, Kurunegala, Matara and Hambantota districts.

IMD NCMWRF Forecast:

 4^th  of Sep: Not Available

 5^th of  Sep: Not Available 

IRI Model Forecast: 

From 4^th – 9^th Sep: Total rainfall up to 75 mm is expected in Batticaloa, Ampara and Monaragala districts; and up to 25 mm in most parts of the island.

MJO based OLR predictions:

For the next 15 days: 
MJO shall suppress the rainfall in Sri Lanka. 

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

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