Weekly Hydro-meteorological Report, 20 August, 2015

Highlights:


SSignificant amount of rainfall was only observed in north central and central regions of the country on the 15th and 16th August with up to 70 mm magnitude. The rest of the country did not receive much rainfall. Dry conditions were observed in the northern, western and eastern regions of the country. NOAA models predict rainfall in south western and central regions of the country in the next fortnight.
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Summary

Monitoring


Weekly Monitoring:During the time period 11th August – 17th August 2015, the whole country received average rainfall up to 20 mm. On 11th, 12th and 13th August, the whole country did not receive much rainfall. On 14th August northern region of Moneragala and eastern region of Polonnaruwa received rainfall up to 30 mm. Rainfall up to 70 mm observed in North central province, Vavuniya, Mullaitivu, Mannar, Trincomalee, Matale, northern region of Kandy, eastern regions of Kurunegala and Puttalam, northern region of Kegalle on 15th August. Kurunegala, Puttalam, Gampaha, Anuradhapura, Hambantota, western region of Polonnaruwa, northern region of Matale and western region of Matara received rainfall up to 70 mm on 16th August. On 17th August, southern region of Kurunegala received rainfall up to 70 mm.


Monthly Monitoring:: In the month July 2015, south western region of the country received above average rainfall of up to 6 mm/day. The rest of the country received below average rainfall during this month.

Predictions

14-day prediction: NOAA NCEP models predict rainfall in south western region of the country during 19th August– 1st September. During the first week, south western region shall receive rainfall up to 45 mm and central and north central regions shall receive rainfall up to 35 mm. South western region shall receive up to 65 mm rainfall in the following week and the rest of the country shall receive rainfall up to 45 mm.

IMD WRF Model Forecast & IRI forecast: According to the IMD WRF model western and eastern regions of the country shall receive rainfall up to 7 mm and some regions in Colombo and Puttalam shall receive rainfall up to 35 mm on 21st August. The same rainfall pattern shall continue on the 22nd as well. IRI CFS model predicts up to 50 mm total 6 day rainfall on the northern, north eastern, central and south western regions of the country during 19th- 24th August 2015.

Seasonal Prediction:As per IRI Multi Model Probability Forecast for July to September, the total 3 month precipitation has a 40% chance of being below average. The 3 month temperature has more than 70-80% likelihood in the entire country of being in the above-normal tercile during this period.

PACIFIC SEAS STATE August 13, 2015 :During late July through early-August 2015 the SST was at a moderate El Niño level. All atmospheric variables support the El Niño pattern, including weakened trade winds and excess rainfall in the east-central tropical Pacific. The consensus of ENSO prediction models indicate continuation of moderate, and likely becoming strong, El Niño conditions during the July-September 2015 season in progress. Further strengthening between summer and fall is likely, with the event lasting into early 2016.
INDIAN OCEAN STATE : 1 0C above average temperature was observed around Sri Lanka.
MJO STATE :MJO is weak and therefore shall not have a significant impact on the rainfall in Sri Lanka.