Weekly Hydro-meteorological Report, 16 October, 2014

Highlights

Monitoring and Prediction

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

Monitoring


Weekly Monitoring::From 08th to 10th of October heavy rainfall was observed throughout the country averaging up to 20 mm. During 11th to 13th, rainfall was observed only around the south-west region. On 14th of October very high rainfall was observed in northern-central region averaging around 40 mm-60 mm. Ratnapura, Polonnaruwa and Trincomalee and surrounding areas received the highest rainfalls (up to 140 mm) 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 decreased from 18 mm to 10 mm within a week.

Predictions

14-day prediction:The south-west region shall receive total rainfall more than 135 mm during 15th October to 21st October. Rainfall is expected to increase throughout the country during 22nd to 28th of October 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 on the 17th of October. By 18th of October the south-west and central regions shall receive a very high rainfall around 64.5 mm-124.5 mm with the rest of the country receiving an average of 2.5 mm-7.6 mm. Heavy rainfall continues in the Indian Ocean as previous week. Extremely heavy rainfall is expected during 15th – 20th October in the central region of the country.

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

PACIFIC SEAS STATE October 9, 2014 :During September through early October the observed ENSO conditions moved to those of a borderline El Niño. Most of the ENSO prediction models indicate weak El Niño conditions during the September-November season in progress, strengthening slightly and peaking at weak strength during winter 2014-15 and lasting into the first few months of 2015.
INDIAN OCEAN STATE :Around 0.50C above average sea surface temperature was observed towards the west coast.
MJO STATE :MJO is in Phase 8 in the Western Hemisphere and therefore shall slightly enhance the rainfall in Sri Lanka.