Weekly Hydro-meteorological Report, 04 October 2012

Summary

Monitoring


Weekly Monitoring: During 27th of September- 2nd of October, rainfall ranged between 0-60 mm. Maximum rainfall of 60 mm was observed on the 27th for Jaffna peninsula. During this week Southern half of the island received low rainfall. On the 28th, Jaffna peninsula received heavy rainfall while the rainfall on the rest of the country was much less. During the next 3 days, rainfall gradually diminished and by the 2nd of October rainfall desisted completely.

Monthly Monitoring: In September, Central and South Eastern regions of the country received below average rainfall and the rest of the country received above average rainfall. Particularly Western, South Western and Jaffna peninsula regions were observed having a high positive anomaly.

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Predictions

7-day prediction: During this week, an accumulated rainfall of 5 mm – 55 mm is predicted for the Southwestern region of the island.

IMD WRF Model Forecast & IRI forecast: On 29th September IMD WRF Model predicts less than 8 mm rainfall for Jaffna peninsula. On the 30th, model forecasts less than 8 mm rainfall for Jaffna peninsula and less than 2.5 mm id predicted for the Western coastal areas of the country. NOAA models forecast 25 mm rainfall for the entire country.

1 Month Prediction: Overall- Rainfall is predicted to be in the range 0-6 mm with the highest amount of rainfall expected around 11th of October. Rainfall shall decrease during 5th-6th October. Rainfall shall increase drastically during 7th-11th & it shall reduce till 14th. Thereafter till 21st, rainfall shall increase with different rates. Thereafter rainfall shall gradually decrease till 27th. Thereon rainfall shall increase. Western Slopes- Same rainfall pattern shall exsits as mentioned for the overall country. But during 14th-21st rainfall shall show significant fluctuations. Eastern slopes- Same rainfall pattern shall exsits as mentioned for the overall country. Northern- During 03rd-21st rainfall shall increase gradually with different rates of fluctuations. Thereafter rainfall shall decrease gradually 25th & it shall increase thereafter.

Seasonal Prediction: As per IRI Multi Model Probability Forecast for Oct0ber 2012 to December 2012, issued in September 2012, there is a 50%-60% probability for temperature to be above normal in the country while the rainfall is to be climatological.