Weekly Hydro-meteorological Report, 4 September, 2014

Highlights

Monitoring and Prediction

Below average rainfall was observed in the entirety of the country during the month of July, however during August, the precipitation observed over Sri Lanka was above average. Ratnapura district received highest amount of rainfall during August. But in the past week rainfall conditions in Sri Lanka once again was observed to be dry compared to the week before. The only significant rainfall event recorded this week was observed in the sea west of Puttalam.
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Summary

Monitoring


Weekly Monitoring:: During 26th to 29th August no rainfall was observed in the country save for some light rainfall observed throughout the country. On the 30th and 31st of August rainfall up to 20 mm was observed in western and south-western regions of Sri Lanka and the nearby sea. This rainfall increased on the 1st of September with heavy rainfall up to 120 mm observed in the sea west of Puttalam. Rainfall up to 40 mm was observed in the coastal region near Puttalam and coastal regions of Gampaha, Colombo and Kalutara also received rainfall up to 20 mm on the same day.


Monthly Monitoring:An above average rainfall was observed throughout the country with higher precipitation observed in the south-western regions of Sri Lanka during August. Highest rainfall during this month was observed in Ratnapura district.

Predictions

14-day prediction:Up to 75 mm rainfall is expected in South-Western and southern Sri Lanka during 3rd -16th September.

IMD WRF Model Forecast & IRI forecast: According to the IMD WRF model western coastal region and eastern region of Sri Lanka shall receive up to 7.5 mm of rainfall on the 5th of September. On the 6th rainfall increase in the west up to 35 mm while expanding inward. IRI models predict up to 50 mm of cumulative precipitation for the six days starting from 3rd of September in south-western and central regions and in the Jaffna peninsula. Unusually high rainfall events are not expected during these 6 days.

Seasonal Prediction:As per IRI Multi Model Probability Forecast issued in August for the season September to November 2014, Rainfall shall remain climatological while the temperature shall be above normal with 60- 70% probability.

PACIFIC SEAS STATE August 21, 2014 :During July through early-August the observed ENSO conditions were neutral. Most of the ENSO prediction models indicate warming to El Niño levels coming around early northern fall, peaking at weak strength during winter 2014-15 and lasting into the first few months of 2015.
INDIAN OCEAN STATE :Around 10 C above average sea surface temperature was observed around Sri Lanka.
MJO STATE :MJO is at phase 3 in the Indian Ocean and shall enhance rainfall conditions in Sri Lanka