Weekly Hydro-meteorological Report, 6 August, 2015

Highlights:


South western, south eastern and north eastern regions of the country received rainfall while rest of the country did not receive significant amount of rainfall on 28th July – 3rd August 2015. Rainfall up to 50 mm observed in the ocean near Trincomalee and on 29th July, rainfall up to 90 mm was observed in Trincomalee and rainfall up to 80 mm was observed in Moneragala and Ampara. NOAA models predict high rainfall in south western, northern and central regions of the country in the next fortnight.
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Summary

Monitoring


Weekly Monitoring:During the time period 28th July – 3rd August 2015, the entire country was not observed significant amount of rainfall except south eastern, north eastern region and south western region which received high rainfall. On 28th July ocean near Trincomalee received rainfall up to 50 mm and on 29th July, ocean near Trincomalee received rainfall up to 90 mm while northern region of Moneragala and Ampara observed rainfall up to 80 mm. On 30th, 31st July and 1st August, the whole country did not receive significant amounts of rainfall and on 2nd August, Trincomalee received rainfall up to 30 mm while ocean near Trincomalee received rainfall up to 50 mm. On 3rd August rainfall up to 30 mm was observed in Kalutara while ocean near south eastern region received rainfall up to 30 mm.


Monthly Monitoring:: In the month July 2015, western and sabaragamuwa regions of the country received above average rainfall of up to 6 mm/day. The rest of the country received below average rainfall during this month.

Predictions

14-day prediction: NOAA NCEP models predict high rainfall in south western region of the country during 5th – 18th August. During the first week, south western region shall receive rainfall up to 45 mm while rest of the country shall receive slight amounts of rainfall. Rainfall up to 45 mm shall receive in the following week in northern and central regions while south western region shall receive rainfall up to 75 mm.

IMD WRF Model Forecast & IRI forecast: According to the IMD WRF model Western region of the country shall receive rainfall up to 35 mm on 7th August. The rest of the country shall not receive significant amounts of rainfall. Western region of the country shall receive rainfall up to 35 mm on 8th August and Kalutara, Ratnapura and Galle shall receive rainfall up to 65 mm while slight amounts of rainfall shall be observed in the rest of the country. IRI CFS model predicts high rainfall in south western region up to 90 mm total rainfall on 5th– 10th August.

Seasonal Prediction:As per IRI Multi Model Probability Forecast for July to September, the total 3 month precipitation has a 40% chance of being below 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 July 16, 2015 :During late June through mid-July 2015 the SST was at a moderate 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 moderate, and likely becoming strong, El Niño conditions during the July-September 2015 season in progress. Further strengthening between summer and fall is likely, with the event lasting into early 2016.
INDIAN OCEAN STATE : 1 0C above average temperature was observed around Sri Lanka.
MJO STATE :MJO is weak and therefore shall not have a significant impact on the rainfall in Sri Lanka.