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Thursday, July 5, 2012

Weekly Hydro-meteorological Report, 07 July 2012


Weekly Monitoring: During last week (27th June- 2nd July) rainfall ranged between 5 mm - 30 mm. The North- eastern regions of the island received rainfall on the 27th June and 1st of July. Heavy rainfall was observed in the Southern half of the island during 30th June - 2nd July.
Monthly Monitoring: During the month of June some parts of Puttalam, Mannar, Kilinochchi, Jaffna, Anuradhapura and Trincomalee districts experienced above average rainfall, but the surplus is below 20 mm. The rest of the country experienced below average rainfall.
7 Day Prediction: For the coming week an accumulated rainfall of 5 mm - 55 mm is predicted for the southern half of the island.
IMD WRF Model Forecast & IRI forecast: WRF Model Predicts 1 mm - 65 mm rainfall particularly for Gampaha, Colombo, Kalutara, parts of Puttalam and Galle districts on the 06th of July, and rainfall shall drop while spreading towards eastward. For the 07th of July, the Model Predicts 1 mm - 125 mm rainfall for Colombo, Kalutara and Gampaha districts, and rainfall shall decrease towards North, South and eastward directions, and no rainfall is predicted for the eastern side of the island. IRI models forecast up to 20 mm of rainfall for the entire island.

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1 Month Prediction: Overall a rapid increase in rainfall shall be observed during the period of 5th-7th of July. Then it shall decrease gradually till the 21st of July with minor fluctuations during 14th- 17th July. There onwards it shall increase gradually. Western slopes- Nearly the same pattern shall be expected with increased rainfall. Rainfall shall decrease gradually till 21st July with minor fluctuations between 9th-11th and 14th-17th July. Thereafter it shall increase gradually. Eastern slopes- From 6th- 19th July rainfall shall gradually decrease with fluctuations during 10th-11th and 14th-17th and reach minimum forecasted daily rainfall of 1 mm. Thereafter rainfall shall increase drastically. Northern region- Rainfall shall increase during 5th-7th July, and shall decrease with a same rate as previous till 10th July. Rainfall shall decrease gradually till 19th July. Thereafter rainfall shall increase gradually with fluctuations during 19th-20th and 24th-27th July.
Seasonal Prediction: As per IRI Multi Model Probability Forecast for July 2012 to September 2012, issued in June 2012, there is a 45%-50% probability for temperature to be above normal in the country. There is 40% probability for rainfall to be climatological.
Past reports available at
ENSO Update 21 June 2012
Slightly more than half of the ENSO prediction models predict El Nino conditions developing around the August-October season, continuing though the rest of 2012. However over 40% of the models indicate persistence of ENSO neutral conditions. Currently, no models indicate a re- emergence of La Nina conditions.
Inside this Issue
1. Monitoring
a. Daily Satellite Derived Rain fall Estimates b. Monthly Rain fall Estimates c. Decadal (10 Day) Satellite Derived Rainfall Estimates d. Weekly Average SST Anomalies
2. Predictions
a. NCEP GFS Ensemble 1-7 day predictions, NOAA, CPC,USA b. IMD WRF Model Forecast c. Weekly precipitation forecast (IRI) d. 1 month experimental predictions by Paul Roundy and L. Zubair e. Seasonal Predictions from IRI

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