Weekly Hydro-meteorological Report, 20 March 2013

Highlights

Monitoring and Prediction
Western Slopes shall receive much higher rainfall compared to the rest of the country. Western coastal regions also receive high amounts of rainfall until the start of April. Northern and Southern regions shall receive relatively low rainfall.

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Summary

Monitoring


Weekly Monitoring:Rainfall upto 140 mm was observed in South Western region of the country on the 11th of March. Then during the next two days, rainfall diminished in this region while spreading towards South East and Eastern regions of the country. On the 15th the entire country received rainfall with the western half of the island along with North and Uva Provinces receiving more rainfall than the rest of the island. A reduction in rainfall was observed on the 16th and 17th with rainfall diminishing towards the South Western direction of the country.

Predictions

7-day prediction:Entire country shall receive 5-55mm of rainfall during 13th-19th March.

IMD WRF Model Forecast & IRI forecast:Upto 35 mm rainfall is expected in South Western regions of the country. NOAA model predicts less than 40 mm of total rainfall for entire Sri Lanka from 19th -24th March.

1 Month Prediction: Overall- Rainfall shall fluctuate around 4 mm throughout the 30 day period (17th March- 17th April). Western Slopes – Peaks of rainfall are expected around 20th & 29th of March as well as 3rd of April 2013. Western Coast –Peaks are expected around 19th and 31st of March. Rainfall shall be relatively less in the first half of April. Eastern slopes – Only a few millimeters of rainfall is expected in this region. Eastern Coast –Highest rainfall events is expected around 29th of March which shall be followed by a drastical declination in rainfall in the next couple of days. Northern region- Rainfall shall fluctuate around 2 mm with a decreasing trend. Southern Region- No rainfall is predicted until 27th of March and it shall flctuate for the rest of the 30 day period.

Seasonal Prediction:As per IRI Multi Model Probability Forecast issued on February 2013; for March 2013 to May 2013, there is a 40% probability for temperature to be above normal in the country while the rainfall is to be climatological.

PACIFIC SEAS STATE March 7, 2013 :During January and February the observed ENSO conditions have leaned towards La-Nina, but remained in the neutral range. Most of the ENSO prediction models call for neutral ENSO conditions through most of the second quarter of 2013, beyond which there is great uncertainty due to the time of year.

INDIAN OCEAN STATE :The Indian Ocean around Maldives particular to the South continues to have a warm anomaly.