Weekly Hydro-meteorological Report, 21 Aug, 2014

Highlights

Monitoring and Prediction

Heavy rainfall was observed in North Central and Eastern regions of the country ending the drought which persisted in these regions. Very high amounts of rainfall was observed in various parts of the country during the past week. More high rainfall is expected in the coming weeks with high confidence. Sustained El Nino conditions are expected by the end of this year. Sea surface temperature around Sri Lanka has further increased to 10 C.
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Summary

Monitoring


Weekly Monitoring:: No rainfall was observed on the 13th of August and except in Matara and Galle regions, where up to 30 mm rainfall was observed, no rainfall was observed on the 14th as well. Heavy rainfall (excess of 140 mm) was then observed on the 15th in Trincomalee and Mulaitivu districts and nearby sea. Galle and Ratnapura districts also received up to 50 mm rainfall on the same day. The entirety of the country received rainfall on the 16th with North, North-Central, Eastern and South-Western regions receiving up to 60 mm rainfall. Rainfall conditions subsided on the 17th in the entire country except in South-Western region. Rainfall once again increased on the 18th with highest rainfall (up to 80 mm) observed in Ratnapura and Monaragala. On the 19th Rainfall was observed in various parts of the country, highest been observed in Polonnaruwa.


Monthly Monitoring:A less than average rainfall was observed throughout the country during July.

Predictions

14-day prediction:Up to 55 mm rainfall is expected in South-Western Sri Lanka during 20th- 26th August. Same amount of rain is expected during 27th August- 2nd September in a smaller region in the South-West.

IMD WRF Model Forecast & IRI forecast: According to the IMD WRF model the entirety of Sri Lanka shall receive rainfall during 23rd and 24th August. Heavy rainfall up to 125 mm is expected in Ratnapura on the 23rd and in Colombo on the 24th. IRI models also predicts heavy rainfall throughout the country during 20th- 25th August with up to 200 mm rainfall in South-Western coastal region.

Seasonal Prediction:As per IRI Multi Model Probability Forecast for August to October 2014, rainfall shall tend towards near-climatological across Maldives while the seasonal temperature this season shall tend towards the above normal tercile across the Maldives with a 70% probability.

PACIFIC SEAS STATE August 7, 2014 :During June through July the observed ENSO conditions remained near the borderline of a weak El Niño condition in the ocean, but the atmosphere so far has shown little involvement. Most of the ENSO prediction models indicate more warming coming in the months ahead, leading to sustained El Niño conditions by the middle or late portion of northern summer.
INDIAN OCEAN STATE :More than 10 C above average sea surface temperature was observed around Sri Lanka.
MJO STATE :MJO is at phase 1 and shall not affect the rainfall in Sri Lanka