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Thursday, June 28, 2012

Weekly Hydro-meteorological Report, 28 June 2012


Weekly Monitoring: During last week (19th - 26th June) rainfall ranged between 5 mm - 20 mm. On the 21st the entire country received rainfall. Maximum 20 mm of daily rainfall was recorded at Matara, Kalutara, Galle on 23rd, 24thand Batticaloa on 25th-26th respectively. On the remaining days less than 20 mm of rainfall was scattered in different places of Sri Lanka.
Monthly Monitoring: During the month of May some parts of Galle, Matara, Ratnapura and Hambantota districts experienced above average rainfall, but the surplus is below 30 mm. Below average rainfall was experienced in rest of the country.
7 Day Prediction: For the coming week, accumulated rainfall of 5 mm - 75 mm is predicted for the Southwestern regions of the island. An accumulated rainfall 5 mm – 55 mm of rainfall is predicted for the entire island.

IMD WRF Model Forecast & IRI forecast: WRF Model Predicts 1 mm - 36 mm rainfall particularly for the Kalutara, Colombo, Gampaha, Puttalam, Kegalle and parts of Kurunegala & Ratnapura districts on the 29th of June, and rainfall shall drop while spreading towards eastward. For the same day less than 8 mm of rainfall is predicted for some parts of Trincomalee, Batticaloa, Ampara, Monaragala and Badulla districts. For the 30th of June, the Model Predicts 1 mm - 65 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 25 mm of rainfall for the entire island with fluctuations
1 Month Prediction: Overall a rapid increase in rainfall shall be observed during the period of 27th-29th of June. Then it shall decrease gradually till the 12th of July with minor fluctuations during 6th- 9th July. There onwards it shall increase gradually. Western slopes- Nearly the same pattern shall be expected with increased rainfall. Rainfall shall decrease gradually till 13th July with minor fluctuations between 1st-3rd & 6th-8th July. Thereafter it shall increase gradually. Eastern slopes- During 27th-28th June rainfall shall increase. From 28th June - 11th July rainfall shall gradually decrease with fluctuations. Thereafter rainfall shall increase drastically. Northern region- Rainfall shall increase during 27th-28th June, and shall decrease with a same rate as previous till 2nd July. Rainfall shall decrease gradually till 9th July. Thereafter rainfall shall increase gradually with fluctuations during 11th-12th & 16th-18th 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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