Weekly Hydro-meteorological Report, 30 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::On 22nd of October heavy rainfall was observed in the south-west oceanic region while Ratnapura, Gampaha and Trincomalee districts have received around 50 mm average rainfall. From 23rd to 25th, about 40 mm rain was observed within the entire country while it has reduced up to 20 mm during 26th to 28th October.


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 south-west region shall receive total rainfall more than 125 mm during 29th October to 04th of November. Rainfall is expected to increase throughout the country during 05th of November to 11th 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 northern, north-eastern and south-eastern regions shall receive high rainfall around 7.5 mm on the 01st of November. By 02nd of November the entire country shall receive rainfall around 7.5 mm-35 mm. High rainfalls continue in the Indian Ocean as previous week. Heavy rainfall is expected during 29th October -03rd November in the entire country with around 100 mm – 150 mm rainfall in south-eastern region.

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.