Weekly Monitoring: During the last week (1st-7th August) rainfall ranged between 0mm-20mm. There was no significant rainfall experienced at the beginning of the week. A scattered rainfall was experienced during 4th-5th of August almost all over the island, but maximum rainfall had not exceeded 10mm. In the latter part of the week low rainfall was experienced up to about 5mm and while some parts of the Gal Oya basin experienced up to about 20mm rainfall.
Monthly Monitoring: During July, southern half of the island experienced a below average rainfall with an increased below average particularly in the Western and South Western regions. It clearly reflects the deficit of the South West Monsoon rainfall up to now. The rest of the island experienced an above average rainfall with a higher intensity in the Trincomalee district while some parts of the Moneragala district also experienced an above average rainfall.
7 Day Prediction: For the coming week an accumulated rainfall of 35 mm - 45 mm is predicted for the entire island. IMD WRF Model Forecast & IRI forecast: On the 11th , IMD predicts 1mm-65mm rainfall for the Puttalam, Gampaha, Colombo, Kalutara, Ratnapura and Galle districts. A higher rainfall of about 65mm is predicted particularly for the Gampaha, Colombo and Kalutara districts. 1mm-3mm rainfall is predicted for some parts of the Ampara and Batticaloa districts .On the 12th , 1mm-36 mm rainfall is predicted for same regions except Batticaloa and Ampara districts. A higher rainfall is predicted for Colombo and Kalutara districts and some parts of Ratnapura District .NOAA models forecast up to about 70mm of total rainfall for the coming week (7 Aug-12 Aug) particularly for the Western, South Western and Central Highlands of the country while 40mm-50mm for the rest of the country.
1 Month Prediction: Overall - Rainfall shall increase dramatically with minor fluctuations till the15th August followed by a rapid decrease till the 19th. There shall be no siginficant rainfall during 19th-27th. Thenafter again it shall show a rapid increase till the 30th but no high rainfall shall be expected. Western Slopes- A gradual decrease with minor fluctuations shall be observed till the 16th followed by a rapid decrease till the 20th . Thenafter there shall be no significant rainfall till the 29th . It shall again show a rapid increase after 29th August but no high rainfall shall be expected. Both Eastern and Northern regions shall show a rainfall fluctuation. Eastern slopes shall experience up to a maximum of about 7.5mm of rainfall while Northern region up to about 6mm.
Seasonal Prediction: As per IRI Multi Model Probability Forecast for August 2012 to October 2012, issued in July 2012, there is a 60%-70% probability for temperature to be above normal in the country. There is 40% probability for rainfall to be climatological.