Weekly Hydro-meteorological Report, 15 October, 2015

Highlights:


Up to 40 mm rainfall was observed in northern, north eastern, western and south western regions of the country during the time period 7th – 13th October. Nuwara Eliya received heavy rainfall up to 70 mm on 11th October and rainfall up to 90 mm was observed in Ratnapura and Anuradhapura on 13th October. Very heavy rainfall is expected in the central region of the country in the next week. Every prediction model predict an increase in the rainfall during the next week.
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Summary

Monitoring


Weekly Monitoring:During 7th – 13th October, few regions of the country received rainfall. On 7th October, southern region of Badulla received rainfall up to 40 mm. On 8th October rainfall up to 40 mm was observed in the northern region of Badulla and rainfall up to 30 mm was observed in southern regions of Ampara and Ratnapura. Rainfall up to 30 mm was observed in Moneragala on 9th October and rainfall up to 65 mm was observed in the ocean near Puttalam on 10th October while western region of Kurunegala and central region of Moneragala received rainfall up to 30 mm. Rainfall up to 70 mm was observed in Nuwara Eliya on 11th October while southern region of Polonnaruwa and Moneragala received rainfall up to 40 mm. On 12th October, ocean near Puttalam received rainfall up to 65 mm and ocean near Jaffna received rainfall up to 30 mm. On 13th October rainfall up to 90 mm was observed in Ratnapura and Anuradhapura while western region of the country received rainfall up to 80 mm.


Monthly Monitoring::In August 2015 most of south western, north western and north central regions received above average rainfall. Colombo district, central and eastern provinces received below average rainfall. Highest rainfall was observed in Ratnapura district. Southern sea of the country also received above average rainfall during this month.

Predictions

14-day prediction: NOAA NCEP models predict relatively high rainfall in south western region of the country compared to the rest of the country during 14th - 20th October. Total rainfall up to 85 mm is expected during the week in the south western region and total rainfall up to 55 mm is expected in the rest of the country except the northern region. These models predict that the rainfall shall increase during 21st - 27th October with total rainfall up to 135 mm expected in south western region and total rainfall up to 95 mm expected in southern region and the rest of the country shall receive total rainfall up to 55 mm.

IMD WRF Model Forecast & IRI forecast: AAccording to the IMD WRF model rainfall up to 125 mm is expected in Badulla, southern region of Kurunegala and Polonnaruwa on 16th October while central province shall receive heavy rainfall up to 65 mm and rest of the country also shall receive rainfall. On 17th October rainfall up to 65 mm is expected in Hambantota, Galle, Kalutara and Ratnapura while rainfall up to 35 mm is expected in central and southern regions. IRI CFS models predict very heavy rainfall in the central region of the country towards the eastern slopes of the central mountain, Up to 200 mm rainfall is expected between 14th to 19th October in Central mountains.

Seasonal Prediction:As per IRI Multi Model Probability Forecast for October to December, the total 3 month precipitation has 50% likelihood of being above 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 October 8, 2015 :During late September through early October 2015 the tropical Pacific SST was at a strong 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 strong El Niño conditions during the September-November 2015 season in progress. Some further strengthening into later fall is possible, with the event lasting well into spring 2016.
INDIAN OCEAN STATE : Neutral sea surface temperature was observed around Sri Lanka.
MJO STATE :MJO is weak and therefore significant impact on rainfall is not expected.