Weekly Hydro-meteorological Report, 27 June, 2013

Highlights

Monitoring and Prediction
In the coming week Southwestern regions shall experience higher rainfall compared to the rest of the island. Compared to the rest of the island Kalutara, Galle and Ampara districts shall receive heavier rainfall on the 28th of June. However, no rainfall is being shown for the 29th for the entire country. Existing rainfall shall increase slightly after June 27th and shall persist with variations (6-9 mm/day) till 10th of July in most regions of Sri Lanka. Around 4th July rainfall events shall be significant for the western coastal regions and Southern regions of Sri Lanka.

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Summary

Monitoring


Weekly Monitoring:Rainfall ranged between 5-90 mm during 19th-25th June 2013. 20th was dryer than rest of the days of the week. Except for a few regions in the Northern Province, the entire country received a significant amount of rainfall from 21st-23rd June.


Monthly Monitoring:Sri Lanka received an above average rainfall during the month of May. The entire country received less than 15 mm of daily rainfall, with Western province receiving the highest rainfall during the month (10-15 mm/day).

Predictions

7-day prediction:Southwestern regions shall receive 5-55 mm of rainfall during 26th June-2nd July 2013.

IMD WRF Model Forecast & IRI forecast:For 28th June, IMD WRF model predicts less than 35 mm of rainfall for Kalutara & Galle districts which shall reduce and spread towards the coastal belts of Puttalam & Matara districts and parts of Ratnapura & Kegalle districts. On the same day Ampara district shall receive less than 35 mm of rainfall & shall spread in a reducing manner towards the coastal belts of Batticaloa district. For the 29th of June, dry conditions are predicted for the entire country. NOAA model predicts dryer condition during 25th-30th June for the entire country compared with the past weeks.

1 Month Prediction:Overall- Existing rainfall shall increase slightly after the 27th of June, and shall persist with variations (6-9 mm/day) till 10th of July. But no significant rainfall events shall be expected. Western Slopes – The rainfall pattern persisting in the entire country shall be observed in this region with higher amounts of rainfall. But the rate of rainfall increase shall be higher than the entire country. Western Coast – The rainfall pattern existing in the entire country shall be present in this region with differing amounts of rainfall, and a significant amount of rainfall can be expected around 4th July. Eastern Slopes – The rainfall will gradually increase till it reaches a significant rainfall event around 28th. Eastern Coast – Rainfall shall increase till the 28th & shall remain constant around 10-12 mm/day thereafter. Northern region- The decreasing trend in rainfall shall persist till 6th July. Southern Region- Rainfall shall remain around 2-4 mm/day till 4th July & there shall be a significant rainfall event around 4th July.

Seasonal Prediction:As per IRI Multi Model Probability Forecast issued on June 2013; for July 2013 to September 2013, there is a 50-60% probability for temperature to be above normal in the country while the rainfall is to be climatological.

PACIFIC SEAS STATE June 20, 2013 :During May through mid-June observed ENSO conditions remained neutral. Most of the ENSO prediction models indicate a continuation of neutral ENSO into northern autumn. However few models, mainly but not exclusively statistical models, call for cooling towards borderline or weak La-Nina conditions during the coming northern summer season into the latter part of the 2013.

INDIAN OCEAN STATE :The sea surface temperature around Sri Lanka showed cold anomaly and western seas of the island showed -10C anomaly during 16th-22nd June 2013.