Weekly Hydro-meteorological Report, 31 July, 2014

Highlights

Monitoring and Prediction


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Summary

Monitoring


Weekly Monitoring:: During 23rd – 25th July no rainfall was observed in any part of the country. On the 26th light rainfall was observed in south western region of the country as well as in the sea toward North East of the country. On the 27th rainfall increased covering the entire southern half of the country. Up to 50 mm of rainfall was observed on this day. Rainfall shifted towards south west on the 28th with heavy rainfall observed in the south western sea. Once again rainfall completely ceased on the 29th.


Monthly Monitoring:The southwest monsoon was active during the month of June. Due to this the south western region received higher rainfall than rest of the country. The entire southern half of the island received rainfall during this month but except for Colombo, Kaluthara, Galle, Matara, Ratnapura, Kegalle, western areas of Nuwara-Eliya and southern areas of Gampaha districts, rainfall received in the country was below-average. In the above mentioned districts up to 200 mm of excess rainfall, compared to the average rainfall received in the past during June, was observed.

Predictions

14-day prediction:Up to 45 mm rainfall is expected in the south western parts of the country during 30th July to 5th August. Rainfall shall be intensified during 6th – 12th August.

IMD WRF Model Forecast & IRI forecast: According to the IMD WRF model western half of the country shall receive rainfall on the 1st and 2nd of August. Heavy rainfall is expected in the Gampaha district on the 1st. IRI models also predict up to 50 mm rainfall during 30th July to 4th August. No extreme rainfall events are expected during this period.

Seasonal Prediction:As per IRI Multi Model Probability Forecast issued on July 2014; for August 2014 to October 2014, the precipitation shall be climatological while there is a 70% chance that temperature shall be above normal.

PACIFIC SEAS STATE July 17, 2014 :During June through early-July the observed ENSO conditions remained near the borderline of a weak El Niño condition in the ocean, but the atmosphere so far has shown little involvement. Most of the ENSO prediction models indicate more warming coming in the months ahead, leading to sustained El Niño conditions by the middle or late portion of northern summer.
INDIAN OCEAN STATE :A 0.5⁰C positive sea surface anomaly was observed around Sri Lanka.
MJO STATE :MJO is at phase 7 in the Western Pacific and shall slightly suppress precipitation in Sri Lanka.