Weekly Hydro-meteorological Report, 26 March, 2015

Highlights


No rainfall was observed during the previous weeks but many climate models predict rainfall during the next week. NOAA/ CFS model predicts up to 100 mm total 6 day-rainfall in Badulla area in the next few days without any heavy rainfall events.
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Summary

Monitoring


Weekly Monitoring:: No rainfall was observed in any part of the country during 18 th - 24 th March 2015.


Monthly Monitoring: After a dry January, almost the entirety of the country received above average rainfall during February. Only places where less than average rainfall was observed are Puttalam, Kurunegala and Polonnaruwa districts. Batticaloa and Ratnapura areas received highest rainfall during this month. Decreased rainfall was observed during the first 10 days of March compared to the last 8 days of February. In March until the 10 th , rainfall was mostly observed in the western and southwestern parts of the country.

Predictions

14-day prediction: NOAA NCEP models predict rainfall during 25 th - 31 st March in the whole country up to 55 mm. Thereafter until 7 th of April no rainfall is expected in the country.

IMD WRF Model Forecast & IRI forecast: According to the IMD WRF model, up to 35 mm rainfall is expected on the 27 th of March in the eastern side of the country. The rainfall is expected to increase on the 28 th . Eastern to central region as well as south western region of the country shall receive up to 35 mm rainfall and the rest of the country shall also receive light rainfall. NOAA/CFS models predict Up to 100 mm rainfall in Badulla district and up to 75 mm rainfall in adjacent districts during 25 th - 30 th March 2015. However extreme rainfall events are not predicted during this period.

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 March 19, 2014 :During February through midMarch 2015 the SST just met the thresholds for weak Niño conditions. During the last month, 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 around Sri Lanka.
MJO STATE :MJO is in phase 8. Therefore rainfall in Sri Lanka shall be suppressed due to this.