Weekly Hydro-meteorological Report, 6 June, 2014

Highlights

Monitoring and Prediction
Existing rainfall condition shall increase further till 10th and gradually decrease till 14th June 2014. For western slopes and coasts, rainfall is likely to decrease during prediction period (6th-12th June 2014). However, for the eastern slopes and coasts rainfall is likely to increase during the prediction period and significant rainfall events are expected during 9th-20th June. For northern and southern regions significant rainfall events are expected during 7th-11th June 2014.

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Summary

Monitoring


Weekly Monitoring:During 27th May-3rd June 2014, Sri Lanka received rainfall ranged 5-145 mm for most of the regions in southern 2/3rd of Sri Lanka. Maximum of 145 mm received for Ratnapura, Kegalle, Gampaha and Kalutara districts on 1st & 2nd June 2014.


Monthly Monitoring:Ampara and Anuradhapura districts received above normal rainfall during May 2014 and Gampaha district received highest negative anomaly of rainfall during May 2014.

Predictions

14-day prediction:During 4th-10th and 11th-17th June 2014, South and Southwestern regions of Sri Lanka shall receive 55-95 mm and less than 55 mm of rainfall, respectively. For the same period rainfall shall decrease towards northwards.

IMD WRF Model Forecast & IRI forecast: For 6th of June, IMD WRF model predicts less than 36 mm/day of rainfall for Kalutara-Puttalam coastal districts and Ratnapura and, rainfall is likely to spread in reducing manner towards central hills. For 7th June 2014, the model predicts significant rainfall (less than 125 mm/day) for Kegalle, Nuwara-Eliya and Kandy districts. IRI model predicts rainfall of 150-200 mm/6 days for Colombo-Kalutara districts during 4th-9th June 2014.

1 Month Prediction:Overall-Existing rainfall condition shall increase further till 10th and gradually decrease till 14th June 2014. Western Slopes - Existing rainfall condition shall decrease gradually through the prediction period (6th-12th June 2014). Western Coasts – The rainfall pattern persisting in the entire country shall observe in this region. Eastern Slopes- Existing rainfall condition (less than 6 mm/day) shall remain constant till 13th and thereafter rainfall is likely to increase drastically. Eastern Coasts- Existing rainfall shall increase gradually and significant rainfall events are expected during 9th-20th June 2014. Northern- Existing rainfall shall increase gradually till 8th and significant rainfall event is likely to observe during 7th-9th June. Thereafter rainfall shall decrease. Southern Region- Existing rainfall shall increase gradually till 10th and significant rainfall event is likely to observe during 9th-11th June. Thereafter rainfall shall decrease till 14th June 2014.

Seasonal Prediction:As per IRI Multi Model Probability Forecast issued on May 2014; for June 2014 to August 2014, there is a more than 70% probability for temperature to be above normal for Hambantota district and 60-70% probability for temperature to be above normal for rest of the regions in Sri Lanka in the country while the rainfall is to be climatological.

PACIFIC SEAS STATE May 15, 2014 :During April through mid-May the observed ENSO conditions moved from warm-neutral to the borderline of a weak El Niño condition. Most of the ENSO prediction models indicate a continued warming trend, with a transition to sustained El Niño conditions by the early northern summer.
INDIAN OCEAN STATE :Sea surface temperature around Sri Lanka showed + 0.50C anomaly during 25th-31st May 2014.
MJO STATE :MJO is at phase 2 and shall have an impact on the rainfall in Sri Lanka.