Weekly Hydro-meteorological Report, 16 April, 2015

Highlights


Heavy rainfall was observed in Sri Lanka in South western and Mannar regions which reached up to 140 mm in magnitude. NOAA models predict very heavy rainfall in the next 6 days in Badulla region.
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Summary

Monitoring


Weekly Monitoring::Rainfall was observed throughout the country during 7 th - 13 th of April 2015. Up to 120 mm rainfall was observed on the 7 th in South-western and north central regions of the country. The highest rainfall during this week was observed on the 12 th in Mannar where the magnitude of the rainfall exceeded 140 mm. Up to 40 mm rainfall was observed on 9 th , 10 th and 13 th and 8 th and 11 th of April was relatively dry.


Monthly Monitoring: In March 2015 the western side of the country received above average rainfall averaging up to 12 mm/day while the rest of the country received below average rainfall. During the first ten days of April heavy rainfall was observed on the western half of Sri Lanka.

Predictions

14-day prediction: NOAA NCEP models does not predict a large amount of precipitation in Sri Lanka but predict very heavy rainfall in southernmost regions in India during the next two weeks (15 th - 28 th April) which can serve as a warning for Sri Lanka.

IMD WRF Model Forecast & IRI forecast: According to the IMD WRF model, up to 125 mm rainfall is predicted for Hambantota while there shall be heavy rainfall in south and south-western regions on the 17 th of April. On the 18 th the rainfall shall decrease but coastal regions of Hambantota shall continue to receive very heavy rainfall. NOAA/CFS 6 day forecast predicts very heavy rainfall reaching up to 200 mm in the region surrounding Badulla.

Seasonal Prediction:As per IRI Multi Model Probability Forecast for April to June, the total 3 month precipitation shall be climatological. The 3 month average temperature has more than 60- 70% likelihood of being in the above-normal tercile during this period.

PACIFIC SEAS STATE April, 2014 :During March through early April 2015 the SST just met the thresholds for weak Niño conditions. Some of the atmospheric variables began indicating an El Niño pattern more than they had been earlier, including trade wind weakening and excess rainfall migrating farther to the east. The consensus of ENSO prediction models indicate weak El Niño conditions during the March-May 2015 season in progress, continuing and strengthening El Niño toward mid-2015.
INDIAN OCEAN STATE :Neutral sea surface temperature was observed in the sea immediately around Sri Lanka.
MJO STATE :MJO is weak and therefore shall not have a significant impact on the rainfall