Weekly Hydro-meteorological Report, 27 September 2012

Summary

Monitoring


Weekly Monitoring: During the last week (20th- 25th September) rainfall ranged between 0 mm- 70 mm. During this week rainfall was observed for the entire country. Maximum rainfall of 70 mm was observed for the places at Monaragala district on 21st and for the places at Galle and Matara Districts on 22nd. Northern half of the island received significant amount of rainfall in this week compared to previous weeks.

Monthly Monitoring: During August South Western, Western and Some regions 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

7-day prediction: During this week, an accumulated rainfall of 5 mm – 35 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 65 mm of rainfall for the Western province & Puttalam district. For the same day 3-37 mm of rainfall is predicted for western half of the island as well as North and Northeastern provinces. On 30th model forecasts less than 65 mm of rainfall for the western coastal regions & it shall diminish towards the inside the country. But for the eastern half of the island, the model predicts no rainfall. NOAA models forecast Predicts 50 mm rainfall for the entire country.

1 Month Prediction: Overall- Rainfall shall increase during 29th September- 1st October & it shall decrease gradually till 5th October. Rainfall shall increase gradually during 5-11th October & it shall decrease till 15th. Western Slopes- Rainfall shall increase during 28th September- 1st October & it shall fluctuate between 0 and 8 mm during 1st-11th October, with highest rainfall expected on 1st, 11th and 21st. Therafter rainfall shall decrease. Eastern slopes- Rainfall is not predicted for the 29th September-1st October & 4th-7th October. Small amount of rainfall expected during 1st-4th October. Rainfall shall increase drastically till 12th & it shall show huge fluctuations thereafter. Northern- Rainfall is not predicted until the 6th of October. Rainfall shall increase gradually during 6th-9th & it shall show minor fluctuation between 9th-15th. Thereon rainfall shall decrease till 18th & it shall increasee till 20th. Therafter rainfall shall decrease.

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.