Weekly Hydro-meteorological Report, 16 May, 2013

Highlights

Monitoring and Prediction
For the most of the parts in Sri Lanka, existing rainfall shall decrease till 18th and it shall increase thereafter. However, there shall not be any significant rainfall events. However, southern 1/3rd shall receive more rainfall compared to the rest of the regions in the island. Jaffna peninsula shall receive low amount of rainfall on 18th May 2013.

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Summary

Monitoring


Weekly Monitoring:Rainfall ranged between 5-145 mm during 6th-13th May 2013. Maximum rainfall was observed on the 6th May and 13th May in Gampaha and Ratnapura districts, respectively. During this period, more or less the entire country experienced rainfall and heavy rainfall concentrated on 12th and 13th May.

Predictions

7-day prediction:South-western regions shall receive 5-55 mm of rainfall during 15th-21st May 2013.

IMD WRF Model Forecast & IRI forecast:For 17th of May 2013, IMD WRF model predicts less than 1 mm of rainfall for the northern half of the island. For 18th of May 2013, IMD WRF model predicts less than 8 mm of rainfall for the Northern Province of the island. For the both days rainfall is not predicted for the southern half of the island. NOAA model predicts higher rainfall for the Southern 1/3rd of the country than the Northern 2/3rd of the country 15th-20th May.

1 Month Prediction:Overall- Existing rainfall condition shall decrease till 18th and thereafter it shall increase with different rates. For the prediction period, 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. Eastern slopes – The rainfall is not predicted till 18th May and thrafter the rainfall pattern existing in the entire country shall be observed. Eastern Coast – Existing rainfall shall continue constantly till 20th May and it shall increase in different rates. Northern region- The rainfall pattern existing in the entire country shall be present in this region. Southern Region- The rainfall is not predicted during 15th-23rd and the pattern existing in the entire country shall be present thereafter.

Seasonal Prediction:As per IRI Multi Model Probability Forecast issued on April 2013; for May 2013 to July 2013, there is a 45-50% probability for temperature to be above normal in the country while the rainfall is to be climatological.

PACIFIC SEAS STATE May 9, 2013 :During March through April the observed ENSO conditions remained in the neutral ENSO conditions. Most of the ENSO prediction models indicate a continues of neutral ENSO into northern autumn, but a few statistical models call for cooling towards weak La-Nina conditions & even smallest set of dynamical models predict warming toward borderline El-Nino conditions.

INDIAN OCEAN STATE :The Indian Ocean around Sri Lanka particular to the Bay of Bengal continues to have a warm anomaly up to 0.5˚C. Warm SST conditions are spreading towards seas north of Sri Lanka.