Weekly Hydro-meteorological Report, 22 October, 2015

Highlights:


Up to 40 mm rainfall was observed in north western, western and southern regions of the country during the time period 14th – 20th October. Gampaha received heavy rainfall up to 160 mm on 18th October and rainfall up to 140 mm was observed in Hikkaduwa. Udawela received rainfall up to 110 mm on 20th October. Every prediction model predict increase of rainfall during the next week.
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Summary

Monitoring


Weekly Monitoring:During 14th–20th October western, north western and southern regions mostly received rainfall. On 14th October rainfall up to 80 mm was observed around Attanagalla while Kuruwita received rainfall up to 50 mm. On 15th October, north eastern region of Kurunegala and Dambulla received rainfall up to 60 mm. Thanamalwila received rainfall up to 50 mm while rainfall up to 40 mm was observed Ratnapura and Embilipitiya on 16th October. Rainfall up to 50 mm was observed around Anamaduwa and in the ocean near Puttalam on 17th October while rainfall up to 30 mm was observed in Mutur, Kinniya, Haputale and Galle. Heavy rainfall up to 160 mm was observed in the coastal region of Gampaha on 18th October while Hikkaduwa received rainfall up to 140 mm. On 19th October, rainfall up to 80 mm was observed in the coastal region of Kalutara while Kuliyapitiya, Rambukkana and Balangoda received rainfall up to 50 mm. Udawela received rainfall up to 110 mm and Galgamuwa received rainfall up to 90 mm on 20th October.


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 21st - 27th October. Total rainfall above 135 mm is expected during the week in the south western region and total rainfall up to 85 mm is expected in the rest of the country except the northern region. Northern region is expected to receive rainfall up to 45 mm. These models predict the rainfall shall be increased during 28th October – 3rd November and total rainfall above 135 mm is expected in southern, central and western regions, total rainfall up to 135 mm is expected in north central region and the northern region shall receive total rainfall up to 95 mm.

IMD WRF Model Forecast & IRI forecast: According to the IMD WRF model rainfall up to 125 mm is expected in Badulla and Moneragala on 23rd October while central and south eastern regions shall receive heavy rainfall up to 65 mm and rest of the country also shall receive slight amounts of rainfall. On 24th October rainfall is expected up to 65 mm in Udawalawe and the coastal region of Hambantota while rainfall up to 35 mm is expected in south eastern region. IRI CFS models predict total rainfall up to 100 mm in south eastern region of the country during 21st - 26th October

Seasonal Prediction:As per IRI Multi Model Probability Forecast for November to January, the total 3 month precipitation shall be climatological. 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 15, 2015 :During late September through mid-October 2015 the tropical Pacific SST was at a strong El Niño level. All atmospheric variables strongly 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 October-December 2015 season in progress. Some slightly further strengthening is possible into later fall, with the event slowly weakening during spring 2016.
INDIAN OCEAN STATE : 1 0C above average temperature was observed around Sri Lanka.
MJO STATE :MJO is weak and therefore significant impact on rainfall is not expected.