Weekly Hydro-meteorological Report, 9, May 2019

Highlights:

•   The IRI weekly rainfall forecast predicts up to 25 mm of total rainfall in the entire island during 8 – 13 May.
•   Between 30 Apr - 6 May: up to 90 mm of rainfall was recorded in Galle and Matara districts on the 3rd.
•  From 30 Apr - 6 May: 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 eastern seas around Sri Lanka.

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Summary

Monitoring

Weekly Monitoring: On April 30th, Ratnapura district received up to 50 mm of rainfall; Kalutara district up to 30 mm; and Kegalle, Kandy, Nuwara Eliya, Galle and Matara districts up to 20 mm. On May 1st, Gampaha and Ratnapura districts received up to 20 mm of rainfall. On the 2nd, Gampaha, Kegalle, Colombo, Kalutara and Ratnapura districts received up to 30 mm of rainfall; and Puttalam, Kurunegala, Galle, Matara and Hambantota districts up to 20 mm. On the 3rd, Galle and Matara districts received up to 90 mm of rainfall; Kalutara, Ratnapura and Hambantota districts up to 50 mm; and Colombo, Gampaha, Kegalle, Nuwara Eliya and Monaragala districts up to 20 mm. On the 4th, Badulla and Monaragala districts received up to 10 mm of rainfall. On the 5th, Monaragala and Hambantota districts received up to 5 mm of rainfall. No significant rainfalls were recorded in any part of the island on the 5th and 6th.

Total Rainfall for past week :  The RFE 2.0 tool shows total up to 75-100 mm in Galle and Matara districts; up to 50-75 mm in Kalutara and Hambantota districts; and 25-50 mm in Gamapaha, Colombo, Kegalle and Ratnapura districts. Above average rainfall up to 50-100 mm is shown for Galle district; up to 25-50 mm in Matara and Hambantota district; and up to 10-25 mm in Gampaha, Colombo, Kalutara and Kegalle districts. Below average rainfall up to 50-100 mm is shown for Badulla, Monaragala and Ampara districts; and up to 10-25 mm in most parts of the island.

Monthly Monitoring: During April – Above average rainfall conditions up to 60 mm were experienced in western regions of Kurunegala district and central regions of Anuradhapura district. Below average rainfall conditions up to 240 mm were experienced by Matale, Kandy, Nuwara Eliya, Kegalle, Colombo, Kalutara, Galle, Matara, Ratnapura, Hambantota, Badulla and Monaragala districts; and up to 180 mm in rest of the island. The CPC Unified Precipitation Analysis tool shows up to 500 mm of total rainfall in Gampaha district; up to 300 mm in Puttalam, Kurunegala, Anuradhapura, Kegalle, Ratnapura, Colombo, Kalutara and Galle districts; up to 200 mm in Matale, Kandy, Nuwara Eliya and Matara districts; and up to 100 mm in Mannar, Vavuniya, Polonnaruwa, Badulla, Monaragala, Batticaloa, Ampara and Hambantota districts.

Predictions

14-day prediction:
NOAA NCEP Models:

From 8th – 14th May: Total rainfall up to 35 mm Gampaha, Colombo, Ratnapura and Galle districts; up to 15-25 mm in Puttalam, Kurunegala, Kegalle and Matara districts; and up to 5-15 mm in Anuradhapura, Polonnaruwa, Matale, Kandy, Nuwara Eliya, Badulla, Monaragala and Hambantota districts.

From 15th – 21st May: Total rainfall up to 65 mm in Galle and Kalutara districts; up to 45-55 mm in Gampaha, Colombo, Ratnapura and matara districts; 35-45 mm in Puttalam, Kurunegala, Kegalle and Hambantota districts; up to 25-35 mm in Matale, kandy, Nuwara Eliya, Badulla and Monaragala districts; and up to 15-25 mm rest of the island.

IMD WRF Model Forecast: 

10th May: Up to 20 mm of rainfall in Ampara district; and up to 10 mm in Batticaloa, Badulla and Nuwara Eliya districts.

11th May: Up to 80 mm of rainfall in Vavuniya and Mullaitivu districts; up to 20 mm Nuwara Eliya district; and up to 10 mm in Trincomalee, Polonnaruwa, Monaragala and Ratnapura districts.

IRI Weekly forecast:
From 8th – 13th May: Total rainfall up to 25 mm is expected in the entire country.

Ocean State (Text Courtesy IRI)
PACIFIC SEAS STATE : April 19, 2018

SSTs in the tropical Pacific maintained a weak El Niño level during March and early April, while temperature anomalies of subsurface waters decreased somewhat but continued to be positive. Patterns in the atmosphere show weak El Niño conditions. Collective model forecasts show a continuation of at least weak El Niño-level SSTs lasting through 2019. The somewhat more cautious official CPC/IRI outlook, with an El Niño advisory, calls for an approximate 65% chance of El Niño prevailing during Jun-Aug, decreasing to 50-55% for Sep-Nov.

INDIAN OCEAN STATE :   0.5 ⁰C above average sea surface temperature was observed in the eastern seas around Sri Lanka.

MJO STATE :  MJO shall suppress the rainfall in Sri Lanka in the next 10 days and shall not have an impact in the following 5 days.