Weekly Hydro-meteorological Report, 18, July 2019

        Highlights       

                                 

·  The IRI weekly rainfall forecast predicts up to 220 mm of total rainfall in southwestern regions of the island during 17 – 22 Jul.

·  Between 10 – 16 Jul: up to 50 mm of rainfall was recorded in Ampara and Polonnaruwa districts on the 14^th.

·  From 9 – 15 Jul: up to 36 km/h, northwesterly 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 July 10^th, Monaragala district received up to 40 mm of rainfall; Kurunegala, Batticaloa and Ampara districts up to 30 mm of rainfall; and Puttalam, Gampaha, Badulla and Hambantota districts up to 20 mm. On the 11^th, Vavuniya district received up to 20 mm of rainfall.  On the 12^th, Polonnaruwa, Matale, Ampara, Kandy and Badulla districts received up to 30 mm of rainfall; and Vavuniya, Anuradhapura, Trincomalee, Kurunegala, Kegalle, Nuwara Eliya, Ratnapura, Kalutara, Galle and Matara districts up to 20 mm. On the 13^th, Ratnapura and Nuwara Eliya districts received up to 20 mm of rainfall. On the 14^th, Ampara and Polonnaruwa districts received up to 50 mm of rainfall; Puttalam and Badulla districts up to 30 mm; and Kurunegala, Gampaha, Colombo, Ratnapura, Kalutara, Matale and Monaragala districts. No significant rainfalls were recorded in any part of the island on the 15^th. On the 16^th, Kalutara and Ratnapura districts received up to 20 mm of rainfall. 

Total Rainfall for the Past Week: The RFE 2.0 tool shows total up to 50-75 mm in Ampara Badulla and Monaragala districts; 25-50 mm in Puttalam, Kurunegala, Matale, Kandy, Nuwara Eliya, Kegalle, Ratnapura, Gampaha, Colombo and Kalutara districts; and up to 25 mm in most parts of the island. Above average rainfall up to 25-50 mm is shown for Badulla, Monaragala and Ampara districts; and up to 10-25 mm in Puttalam, Kurunegala, Matale, Kandy and Ampara districts. Below average rainfall up to 10-25 mm is shown for Vavuniya, Mannar, Trincomalee and Galle districts..

Monthly Monitoring: During June – Above average rainfall conditions up to 60 mm were experienced by Puttalam, Kurunegala. Gampaha, Kalutara, Galle and southern parts of the Ratnapura district. Below average rainfall conditions up to 150 mm were experienced by Kandy and Nuwara Eliya districts; and up to 90 mm in Mannar, Vavuniya, Mullaitivu, Anuradhapura, Polonnaruwa, Batticaloa, Matale, Ampara, Badulla, Monaragala, Hambantoa, Kegalle and Colombo districts. The CPC Unified Precipitation Analysis tool shows up to 200 mm of total rainfall in Puttalam, Gampaha, Colombo, Kalutara, Ratnapura and Galle districts; up to 150 mm in Kurunegala, Kegalle, Nuwara Eliya and Matara districts; up to 100 mm in Badulla and Ampara districts; and up to 75 mm in Batticaloa, Hambantota, Monaragala, Matale and Kandy districts.

Predictions

Rainfall

14-day prediction: 

NOAA NCEP models: 

From 17^th – 23^rd Jul: Total rainfall up to 135 mm Colombo, Kegalle, Ratnapura, Galle and Matara districts; up to 115-125 mm in Puttalam, Kurunegala, Gampaha and Hambantota districts; 105-115 mm in Kandy and Nuwara Eliya districts; up to 95-105 mm in Kandy, Badulla and Monaragala districts; up to 85-95 mm in Matale and Ampara districts; up to 75-85 mm in Mannar and Anuradhapura districts; and up to 65-75 mm in most parts of the island.

From 24^th – 30^th Jul: Total rainfall up to 55 mm in Jaffna districts; up to 35-45 mm Kilinochchi and Mullaitivu districts; up to 25-35 mm in Mannar, Vavuniya, Anuradhapura and Trincomalee districts; and up to 15 mm in rest of the island.

IMD NCMWRF Forecast:

19^th Jul: Not Available

20^th Jul: Not Available

IRI Model Forecast: 

From 17^th – 22^nd Jul: Total rainfall up to 220 mm is expected in Gampaha, Kegalle, Colombo, Ratnapura, Kalutara and Galle districts; up to 200 mm in Puttalam, Kurunegala and Matara districts; up to 150 mm in Kandy, Nuwara Eliya and Hambantota districts; up to 100 mm in Matale district; up to 75 mm in Badulla, Mullaitivu and Trincomalee districts; and up to 50 mm in rest of the island.

MJO based OLR predictions:
For the next 15 days:
MJO shall enhance the rainfall in Sri Lanka. 

Ocean State (Text Courtesy IRI)

Pacific sea state: July 11, 2019

SSTs in the central Pacific maintained at a weak El Niño level during June and early July, while temperature anomalies of subsurface waters cooled to near-average. Some patterns in the atmosphere continue to show El Niño conditions intermittently. Collective model forecasts show a likely transition from weak El Niño conditions to ENSO-neutral by late summer. The official CPC/IRI outlook, still with an El Niño advisory, calls for a 60% chance of ENSO-neutral by Jul-Sep, and neutral remains the most likely category through fall and winter.

Indian Ocean State

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