Weekly Hydro-meteorological Report, 12 December, 2013

Highlights

Monitoring and Prediction
Rainfall shall increase gradually till 15th of December 2013. However, Northern, North-central, and Central provinces are likely to experience moderate rainfall during coming week (10th-17th December 2013). For coming two days (13th & 14th December), Northwestern, Western and central provinces are likely to observe heavy rainfall and rainfall shall decrease towards the North.

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Summary

Monitoring


Weekly Monitoring: During 2nd and 3rd December 2013, rainfall ranged 5-30 mm/day. Maximum rainfall observed on 2nd December for Killinochchi and Jaffna districts. Rest of the days received lower amount of rainfall compared to the beginning of the week. Heavy rainfall prevailed over the Northeastern Sea around Sri Lanka ranging up to 130 mm during the week.


Monthly Monitoring: Moneragala and Ratnapura district received highest average rainfall during the month of November 2013.

Predictions

7-day prediction:During 3rd-9th December 2013, entire Sri Lanka is expected to receive above 75 mm of rainfall. Rainfall is expected to decrease towards Southwest region and Central, North-central and Western provinces shall experience less than 55 mm of rainfall.

IMD WRF Model Forecast & IRI forecast: For 13th of December, IMD WRF model predicts less than 36 mm of rainfall for Uva region and some parts of eastern province shall receive less than 2 mm of rainfall. For 14th of December, IMD WRF model predicts less than 65 mm of rainfall for North Western, Western, and Southern province and rainfall shall diminish towards the North of Sri Lanka. NOAA model predicts the heavy rainfall (more than 75 mm/week) for the Ampara and Batticaloa districts and shall decreases towards the southwest during 11th-17th December 2013.

1 Month Prediction:Overall- Rainfall shall increase gradually till 16th of December. Western Slopes –Rainfall shall increase gradually during 12th-15th December and it shall decrease prominantly thereafter. Western Coast – Rainfall shall vary below 11 mm/day till 16th December. However, western slopes and western coasts shall receive same magnitude of the rainfall. Eastern Slopes– Rainfall shall increase gradually till 17th of December and decrease thereafter. Eastern Coast – The rainfall shall decrease gradually till 17th. Northern region- The rainfall gradually increases till 17th December. Southern Region- The rainfall rate gradually decreases below 2.5 mm till 17th December.

Seasonal Prediction::As per IRI Multi Model Probability Forecast issued on November 2013; for December 2013 to February 2014, 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 November 21, 2013 :During October through mid-November the observed ENSO conditions remained neutral. Most of the ENSO prediction models indicate a continuation of neutral ENSO into the first quarter of 2014. During northern spring and summer a warming tendency is seen in both dynamical and statistical models.

INDIAN OCEAN STATE :Southern sea of Sri Lanka showed +1 degree Celsius anomaly and rest of the seas around Sri Lanka showed neutral seas surface temperature during 24th to 30th November 2013.
MJO STATE :MJO is entering phase 3 and is likely to enter phase 4 during next week. This phenomenon shall influence Sri Lanka rainfall this week.