Weekly Hydro-meteorological Report, 6 September 2012

Summary

Monitoring

Weekly Monitoring: During the last week (29^th August- 04^th September) rainfall ranged between 0 mm- 60 mm. During first half of the week (29 Aug-01 Sep) southern half of the country showed wet conditions with high rainfall in the Western and South Western regions. A scattered rainfall was experienced during second half with more rainfall for the Western, South Western, Southern and Central regions.

Monthly Monitoring: During August South Western, Western and Some parts of Badulla and Ampara districts experienced an above average rainfall with quite high positive anomaly in the South Western region. The rest of the country experienced below average rainfall during this period.

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Predictions

IMD WRF Model Forecast & IRI forecast: On the 7^th IMD WRF model predicts 1mm-36mm rainfall for  the Puttalam, Colombo, Gampaha, Kalutara, Galle and Matara districts and Jaffna Peninsula  with more rainfall of up to about 36mm for Galle and Matara Districts. It also predicts up to 8mm rainfall for some parts of the Ampara, Badulla and Nuwara Eliya Districts. On the 8^th it Predicts up to about 8mm rainfall for the same areas except Matara, Jaffna and Ampara districts with an extension towards Mannar. Further it predicts same rainfall for the Trincomalee area and some parts of the Batticaloa district. NOAA models forecast Predicts up to 50mm total rainfall for the whole country.

1 Month Prediction:  Overall a rapid increase of rainfall shall be expected till the 9^th September followed by a rapid decrease till the 12^th. Thenafter rainfall shall show some fluctuations with low rainfall. Western Slopes- Rainfall shall increase rapidly till the 8^th September followed by a rapid decrease till the 12^th. Thenafter it shall show a decreasing trend with some fluctuations till the 21^st. It shall again show an increasing trend with some fluctuations till the 4^th October. Eastern slopes- Highly fluctuated rainfall shall be expected and the maximum rainfall shall not exceed 4mm. Northern-No Significant rainfall shall be expected.

Seasonal Prediction: As per IRI Multi Model Probability Forecast for September 2012 to November 2012, issued in August 2012, there is a 50%-60% probability for temperature to be above normal in the country while the rainfall is to be climatological.