Weekly Hydro-meteorological Report, 23 September, 2015

Highlights:


Up to 30 mm rainfall was observed in southern and western regions of the country during the time period 15th-21st September. Southern region of the country received heavy rainfall on 18th September up to 80 mm. Every prediction model predict high rainfall in eastern and south western regions during the next week.
Download Full Report




Summary

Monitoring


Weekly Monitoring: During 15th -21st of September, rainfall was mostly observed in western and southern regions of the country. On 15th September rainfall up to 40 mm was observed in the ocean near Colombo and rainfall up to 30 mm was observed in western province and Polonnaruwa. Rainfall up to 40 mm was observed in Moneragala and the ocean near Matara and Hambantota. On 16th September and on 17th September only the ocean near Hambantota received rainfall up to 30 mm. The ocean near Galle received rainfall up to 80 mm on 18th September while Galle and Matara received rainfall up to 60 mm. On 19th September only the ocean near southern province received rainfall up to 30 mm and on 20th September, ocean near Mullaitivu received rainfall up to 60 mm and rainfall up to 30 mm observed in southern region of Kegalle. On 21st September significant amount of rainfall was not observed in any part of the country.


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 high rainfall in the south western region of the country during 22nd -28th September. South western region shall receive total rainfall up to 135 mm during the week while total rainfall up to 85 mm is expected in south eastern region and rest of the country shall receive total rainfall up to 55 mm. These models predict the rainfall shall be slightly decreased during 29th September - 05th October and total rainfall up to 85 mm is expected in south western region and the rest of the country shall receive total rainfall up to 55 mm.

IMD WRF Model Forecast & IRI forecast: According to the IMD WRF model heavy rainfall up to 125 mm shall receive in Vavuniya, Polonnaruwa and the northern region of Badulla on 24th September while Mullaitivu, Badulla, Nuwara Eliya and Matale shall receive rainfall up to 65 mm. The western and southern regions of the country shall receive rainfall up to 35 mm and the rest of the country shall also receive slight amounts of rainfall. Rainfall up to 125 mm is expected in Galle on 25th September and south western region shall receive rainfall up to 65 mm while rest of the country shall receive slight amounts of rainfall. IRI CFS models predict total rainfall up to 100 mm in south western and central regions of the country during 22nd-27th September.

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 September 17, 2015 :During late August through early September 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 : 1 0C above average temperature was observed around Sri Lanka.Indian Ocean Dipole is also active.
MJO STATE :MJO is in phase 4 therefore shall slightly enhance the rainfall in Sri Lanka.