Weekly Hydro-meteorological Report, 29 May, 2013

Highlights

Monitoring and Prediction
For the most of the parts in Sri Lanka, existing rainfall shall decrease till 24th and it shall increase thereafter till the end of the May. However, there shall not be any significant rainfall events for the entire country, except for the Western coasts. For the western coasts, on 24th there shall be significant rainfall trough. Southwestern regions shall receive 5-55 mm of rainfall for the next week. However, there shall be 60-70% probability for temperature to be above normal in the country during June to August 2013.

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Summary

Monitoring


Weekly Monitoring:Rainfall ranged between 5-70 mm during 15th-21st May 2013. Maximum rainfall was observed on the 19th May in Colombo district. On 16th entire country received least amount of rainfall compared to rest of the days in the week.

Predictions

7-day prediction:South-western regions shall receive 5-55 mm of rainfall during 22nd -28th May 2013.

IMD WRF Model Forecast & IRI forecast:For 24th and 25th of May 2013, IMD WRF model predicts less than 1 mm of rainfall for the northern half of the island. For the both days rainfall is not predicted for the southern half of the island. NOAA model predicts slight rainfall (less than 20 mm) for the entire country during 22nd -27th Many 2013.

1 Month Prediction:Overall- Existing rainfall condition shall decrease till 24th and thereafter it shall increase till 29th. For the prediction period (end of the May), there shall not be any significant rainfall events. Western Slopes – The rainfall pattern existing in the entire country shall be present in this region. Western Coast – The rainfall pattern existing in the entire country shall be present in this region. However, on 24th there shall be significant rainfall trough in this region. Eastern slopes – The rainfall pattern existing in the entire country shall be present in this region. Eastern Coast – The rainfall pattern existing in the entire country shall be present in this region. Northern region- The rainfall pattern existing in the entire country shall be present in this region. Southern Region- The exsting rainfall pattern shall increase gradually till the end of the prediction period.

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 May 16, 2013 :During March through May the observed ENSO conditions remained in the 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 season into the latter part of the 2013.

INDIAN OCEAN STATE :The Indian Ocean around Sri Lanka particular to the Bay of Bengal continues to have a cold anomaly up to -0.5˚C.