Weekly Hydro-meteorological Report, 10 September, 2015

Highlights:


Up to 40 mm rainfall was observed in various parts of the country during the time period 1st-7th September. Rainfall was mostly observed in northern and north central regions of the country. The entire country received rainfall on 3rd September where Badulla received rainfall up to 100 mm. Trincomalee and southern region of Moneragala received 70 mm rainfall on 6th September. Every prediction model predict high rainfall in western and south western regions during the next week.
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Summary

Monitoring


Weekly Monitoring:During 1st -7th of September, rainfall observed mostly in North central region. On 1st September, rainfall up to 40 mm observed in the southern region of Mullaitivu and on 2nd September, rainfall up to 30 mm observed in Ampara. Entire country received heavy rainfall on 3rd September while Badulla received rainfall up to 100 mm and Galle, Anuradhapura, Kurunegala received rainfall up to 90 mm. Vavuniya, southern region of Anuradhapura and ocean near Jaffna received rainfall up to 40 mm on 4th September and on 5th September, Mullaitivu observed rainfall up to 40 mm. Trincomalee and southern region of Moneragala received rainfall up to 70 mm on 6th September. On 7th September, only southern region of Kalutara and northern region of Galle received rainfall up to 30 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 the south western region of the country compared to the rest of the country during 9th-15th September. South western region shall receive total rainfall up to 45 mm during this week while rest of the country shall receive total rainfall up to 35 mm. These models predict further increment in rainfall during 16th-22nd September where up to 75 mm total rainfall expected in the south western region and total rainfall up to 55 mm in the rest of the country.

IMD WRF Model Forecast & IRI forecast: According to the IMD WRF model high rainfall up to 65 mm is expected in the coastal region of Puttalam district on 11th September. Western and south western regions shall receive up to 35 mm rainfall on the same day. Other regions shall receive slight amounts of rainfall. Rainfall shall decrease on 12th September but western region shall continue receiving 35 mm rainfall. Light rainfall is possible in other regions of the country. IRI CFS models predict total rainfall up to 50 mm in south eastern, central and south western regions during 8th- 13th September. Total rainfall up to 100 mm shall receive in the ocean near Colombo during this period.

Seasonal Prediction:As per IRI Multi Model Probability Forecast for September to November, 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 August 20, 2015 :During late July through early-August 2015 the 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 August-October 2015 season in progress. Some further strengthening into fall is likely, with the event lasting into spring 2016.
INDIAN OCEAN STATE : 1 0C above average temperature was observed around Sri Lanka.Indian Ocean Dipole is also active.
MJO STATE :MJO is weak and therefore shall not influence the rainfall in Sri Lanka.