Weekly Hydro-meteorological Report, 23 October, 2014

Highlights

Monitoring and Prediction

Very heavy rainfall was observed throughout the country and mostly around the south-west region during the previous week and very high rainfall shall continue in the entire country during next week as well. The south-west sea of Sri Lanka shows an above average sea surface temperature.
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Summary

Monitoring


Weekly Monitoring::Very high rainfall was observed in the entire country throughout the week with highest rainfall observed on 17th of October averaging around 100 mm while there was an average rainfall of 20 mm -40 mm during the remaining days. The south-west region in general has received an extremely high rainfall during the week.


Monthly Monitoring:An average rainfall of 6 mm-10 mm was observed throughout the country with higher precipitation observed in the south-western regions of Sri Lanka during September. Highest rainfall during this month was observed in Ratnapura district. Also the decadal rainfall average was increased from 8 mm to 18 mm within a week.

Predictions

14-day prediction:The entire country shall receive total rainfall more than 95 mm during 22nd October to 28th October. Rainfall is expected to increase throughout the country during 29th of October to 4th of November resulting in very high rainfall more than 135 mm in total.

IMD WRF Model Forecast & IRI forecast: According to the IMD WRF model the entire country shall receive high rainfall around 7.6 mm on the 24th of October. By 25th of October the north-eastern region shall receive rainfall around 2.5 mm-7.6 mm. High rainfalls continue in the Indian Ocean as previous week. Heavy rainfall is expected during 22nd -27th October in the central region of the country.

Seasonal Prediction:As per IRI Multi Model Probability Forecast issued in October for the season November 2014 to January 2015, Rainfall shall remain climatological while the temperature shall be above normal with a high probability.

PACIFIC SEAS STATE October 16, 2014 :During September through early October the observed ENSO conditions retreated from those of a borderline El Niño to a warmish ENSO-neutral state. However, most of the ENSO prediction models continue to indicate development of weak El Niño conditions during the October-December season in progress, peaking at weak strength during winter 2014-15 and lasting through most of northern spring 2015.
INDIAN OCEAN STATE :Around 0.50C above average sea surface temperature was observed towards the south-west coast.
MJO STATE :MJO is weak and therefore it shall not have any influence on rainfall in Sri Lanka.