Weekly Hydro-meteorological Report, 13 June, 2013

Highlights

Monitoring and Prediction
In the coming week, Southwestern regions shall experience significant amount of rainfall, especially Colombo & Kalutara districts. Heavy rainfall shall be observed in the western coastal belt of the island in the coming two days (14th and 15th June). However, in most of regions of Sri Lanka, existing rainfall shall increase gradually till 17th and thereafter it shall show a decreasing trend. Most of the regions shall experience significant amount of rainfall around 17th June.

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Summary

Monitoring


Weekly Monitoring:Rainfall ranged between 5-50 mm during 4th-10th June 2013. Maximum rainfall was observed for the southern half of the island during 7th-8th. However, entire country received rainfall during 4th-8th & magnitude of the rainfall reduced thereafter.

Predictions

7-day prediction:Southwestern regions shall receive 55-105 mm of rainfall & it shall spread in a reducing manner toward the center of the island in North-eastern direction during 12th -18th June 2013.

IMD WRF Model Forecast & IRI forecast:For 14th June, IMD WRF model predicts 65-125 mm rainfall for coastal regions between Colombo-Matara and it shall spread in a reducing manner towards the Northern and Southern coastal regions and, central region of the island. However, eastern half of the island shall not receive rainfall. For 7th May, rainfall pattern exists on 14th shall continue, but amount of rainfall shall between less than 65 mm. NOAA model predicts heavy rainfall for the southwestern regions of Sri Lanka, especially 100-150 mm of daily rainfall shall be present for Colombo and Kalutara districts.

1 Month Prediction:Overall-Existing rainfall shall increase gradually, but it shall remain almost constant (between 6-10 mm/day). However, rainfall shall show decreasing trend. Western Slopes – The rainfall shall show decreasing trend with fluctuations. Western Coast – The decreasing trend of the rainfall shall starts after 17th with fluctuations. Significant rainfall shall be present around 17th. Eastern Slopes – The rainfall gradually increase till 23rd. Eastern Coast – The rainfall increase drastically till 17th (peak of the rainfall the prediction period) and remain between 8-12 mm/day with fluctuations. Northern region- The rainfall shall increase till 17th and shall decrease thereafter. Southern Region- The rainfall pattern shall shows decreasing trend.

Seasonal Prediction:As per IRI Multi Model Probability Forecast issued on May 2013; for June 2013 to August 2013, there is a 60-70% probability for temperature to be above normal in the country while the rainfall is to be climatological.

PACIFIC SEAS STATE June 6, 2013 :During April through May the observed ENSO conditions remained neutral. Most of the ENSO prediction models indicate a continuation of neutral ENSO into northern autumn. However few models, mainly but not exclusively statistical models, call for cooling towards borderline or weak La-Nina conditions during the coming northern summer monsoon into the latter part of the 2013.

INDIAN OCEAN STATE :The cold anomaly which was observed in the Indian Ocean around Sri Lanka had continued during 26th May-1st June 2013.