Weekly Hydro-meteorological Report, 13 December 2012

Highlights

Monitoring and Prediction
Monitoring: Rainfall accumulation of upto 135 mm is expected for the 12-18th in the eastern sea board. The monthly predictions point to high rainfall between 16-21st of December in the Western slopes but lower amounts in the rest of the country.

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Summary

Monitoring


Weekly Monitoring: During 4th-11th December, rainfall ranged between 5-145 mm with highest amount of precipitation observed in Polonnaruwa district on the 5th December. More or less entire country received rainfall on 6th December. During 10th-11th rainfall was not observed for Sri Lanka.

Monthly Monitoring: In October, entire Sri Lanka received above average rainfall. Entire country received more than 100 mm of above average rainfall per month and except for South eastern regions of the island; received 5-80 mm of above average rainfall per month.


Predictions

7-day prediction: During this week, East and South-east regions shall receive more than 135 mm rainfall and rainfall shall spreads westward in a reducing pattern.

IMD WRF Model Forecast & IRI forecast: For the 14th and 15th December, IMD WRF model predicts less than 2.5 mm of rainfall for the Galle district. On 15th IMD WRF model predicts less than 7.6 mm of rainfall for the eastern province. NOAA models forecast mild rainfall for the entire country for the period of 11th-16th December.

1 Month Prediction: Overall- Rainfall shall increase gradually during 13th-16th and it shall decrease till 18th. Rainfall shall increase again during 18th-20th and shall decrease drastically till 24th. Western Slopes- Rainfall shall increase gradually during 13th-16th and it shall shows constant during 16th-17th. Thereafter rainfall shall decrease till 18th and again it shall remain constant during 18th-19th. Rainfall shall increase during 19th-20th and decrease drastically till 22nd. During 22nd-26th rainfall shall increase gradually. Eastern slopes- Rainfall shall increase gradually during 13th-16th and it shall decrease drastically till 18th. Again it shall increase again during 18th-21st and shall decrease gradually till 24th. Northern- Rainfall shall increase gradually during 13th-16th and it shall decrease till 19th. Rainfall shall increase again during 19th-21st and shall decrease till 26th. Rainfall is not predicted for the period of 26th December to 6th January 2013.

Seasonal Prediction: As per IRI Multi Model Probability Forecast for November 2012 to January 2013, issued in October 2012, there is a 50%-60% probability for temperature to be above normal in the country while the rainfall is to be climatological.