Weekly Hydro-meteorological Report, 02 October, 2014

Highlights

Monitoring and Prediction

Heavy rainfall was observed throughout the country during the previous week and further heavy rainfall is expected in the entire country during the next week as well. Badulla, Kandy, Kaluthara and Galle districts shall receive heavy rainfall during this period. Up to 200 mm rainfall is expected in Badulla. Unusually heavy rainfall is expected in the region from Monaragala to Polonnaruwa for the 2nd consecutive week. The north-western sea of Sri Lanka shows an above average sea surface temperature while the south eastern sea shows a below average sea surface temperature.
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Summary

Monitoring


Weekly Monitoring::On the 23rd and 24th of September only light rainfall was observed throughout Sri Lanka. The average rainfall was in the 40 mm-55 mm range during 25th to 28th, mostly in the western, central and north-central regions. On 29th the south-west regions had the highest rainfall of the week while the rest of the areas had light rainfalls.


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:The entire country shall receive total rainfall up to 55 mm during 1st of October to 14th October.

IMD WRF Model Forecast & IRI forecast: According to the IMD WRF model the entire country shall receive high rainfall on the 4th of October. Most of the country shall receive up to 8 mm rainfall with exceptions of central, western and south-western regions, which shall receive up to 125 mm rainfall. By 4th of October entire country shall receive an average rainfall around 35 mm.

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 September 18, 2014 :During August through early September 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 sea surface temperature in northern sea and 0.50C below average in south- eastern sea was observed.
MJO STATE :MJO is in Phase 4 in the Maritime continent and therefore shall slightly enhance the rainfall in Sri Lanka.