Weekly Hydro-meteorological Report, 18 October 2012

Summary

Monitoring


Weekly Monitoring: During 10th-15th of October, rainfall ranged between 0-125 mm. During this week almost all the parts of Sri Lanka received rainfall. On 12th & 13th maximum rainfall of 125 mm was observed in the places at Anuradhapura district.

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 more than 135 mm is predicted for the western half of the island including North-central province and rest of the parts shall receive rainfall of 65-105 mm.

IMD WRF Model Forecast & IRI forecast: On 18th of October Northern half of the island shall receive less than 36 mm rainfall and rainfall shall spread towards southern half of the country with a decreasing pattern. For the Southern province there shall be less than 1 mm rainfall is predicted for the same day. NOAA models forecast 75 mm rainfall for North-Western regions of Sri Lanka and 45 mm rainfall for the rest of the country.

1 Month Prediction: Overall- Rainfall shall fluctuate between 3-6 mm throughout the next 30 days. Western Slopes- During 17th-20th rainfall shall increase drastically & it shall decrease till 25th October. Thereon rainfall shall increase till 29th. Therafter it shall decrease till the end of October. Eastern slopes- Rainfall shall decrease gradually during 18th-21st October & it shall increase drastically till 27th October with minor fluctuation during 24th-25th. Thereafter rainfall shall decrease gradually till the end of October. Northern- Rainfall shall increase drastically during 17th-20th october & it shall decrease gradually till 24th. Again rainfall shall increase drastically till 29th & thereafter rainfall shall shows similar pattern as mentioned in prevoius regions till the end of October.

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.