Weekly Hydro-meteorological Report, 29 October, 2015

Highlights:


Up to 40 mm rainfall was observed in north eastern, western and southern regions of the country during 21st – 27th October. Kalkudah, Kalmunai and Kattankudy received heavy rainfall up to 220 mm on 24th October and rainfall up to 160 mm was observed in the ocean near Trincomalee while Trincomalee received rainfall up to 140 mm on 27th October. Every prediction model predict an increase of rainfall during the next week.
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Summary

Monitoring


Weekly Monitoring:During 21st–27th October western, north eastern and southern regions mostly received rainfall. On 21st October rainfall up to 60 mm was observed around Kuruwita and rainfall up to 50 mm was observed around Kekirawa and Kuruwita on 22nd October. On 23rd October Kegalle, Kuruwita, Eheliyagoda, Dehiattakandiya and western province received rainfall up to 50 mm. On 24th October Kalkudah, Kattankudy and Kalmunai received rainfall up to 220 mm while Moneragala, Polonnaruwa, Hambantota and southern regions of Galle and Matara received rainfall up to 80 mm. On 25th October rainfall up to 50 mm was observed around Kalmunai and Kattankudy while ocean near Batticaloa received rainfall up to 70 mm. Northern region of Moneragala, ocean near Batticaloa and Trincomalee received rainfall up to 120 mm while Vavuniya and Kalmunai received rainfall up to 90 mm on 26th October. Rainfall up to 160 mm was observed in the ocean near Trincomalee on 27th October while Trincomalee received rainfall up to 140 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 28th October – 3rd November. Total rainfall above 135 mm is expected during the week in the south western region and total rainfall up to 115 mm is expected in the rest of the country except the northern region. Northern region is expected to receive rainfall up to 95 mm. These models predict the rainfall shall be decreased during 4th- 10th November and total rainfall above 135 mm is expected in southern region, total rainfall up to 115 mm is expected in north western region and the northern and south eastern regions shall receive total rainfall up to 95 mm.

IMD WRF Model Forecast & IRI forecast: AAccording to the IMD WRF model rainfall up to 65 mm is expected around Nilaveli on 30th October while eastern region shall receive rainfall up to 35 mm and rest of the country also shall receive slight amounts of rainfall. On 31st October, rainfall is expected up to 125 mm in northern region of Kurunegala while rainfall up to 65 mm is expected around Weligama and Pelawatta. Central and southern regions also shall receive rainfall up to 35 mm. IRI CFS models predict total rainfall up to 200 mm in south eastern region of the country during 28th October – 2nd November.

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 phase is in 2 therefore shall slightly enhance rainfall in Sri Lanka.