Weekly Hydro-meteorological Report, 21 November, 2013

Highlights

Monitoring and Prediction
Rainfall shall increase gradually till 27th of November and shall decrease gradually thereafter till 2nd of December. Western coast shall receive significant high rainfall during 26th-29th November. However, significant minimum rainfall is likely to observe during 1st-4th December 2013. For the coming week (22nd-28th November) western coastal regions and Badulla and, Moneragala districts are likely to observe more rainfall compared to the rest of the island.

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Summary

Monitoring


Weekly Monitoring: During 13th-19th November 2013, rainfall ranged 5-60 mm/day. However, entire country received less than 10 mm/day of scattered rainfall throughout the week, except small region in Jaffna 18th November.


Monthly Monitoring: Jaffna and Batticaloa districts received an above average rainfall during the month of September.

Predictions

7-day prediction: During 20th-26th November 2013, western half of the island shall experience 5-35 mm of rainfall and shall spread towards central hills in a decreasing pattern.

IMD WRF Model Forecast & IRI forecast:: For 22nd of November, IMD WRF model predicts less 36 mm of rainfall for the entire Kalutara-Hambantota and Ratnapura districts and some regions in Nuwara-Eliya, Badulla and Moneragala districts. For 23rd of November, IMD WRF model predicts less 36 mm of rainfall for the entire country, except for coastal regions of Kilinochchi-Kalutara and Trincomalee-Ampara districts (less than 1 mm of rainfall). NOAA model predicts heavy rainfall for Badulla and Moneragala districts during 20th -25th November 2013.

1 Month Prediction:Overall- Rainfall shall increase gradually till 27th of November and shall decrease gradually thereafter till 2nd of December. However, significant minimum rainfall is likely to observe during 1st-4th December 2013. Western Slopes – The rainfall pattern persisting in the entire country shall be observed in this region with high amount of rainfall. Western Coast – The rainfall pattern persisting in the entire country shall be observed in this region with high amount of rainfall. However, significant high rainfall is likely to observe during 26th-29th November. Eastern Slopes– The rainfall shall vary below 6 mm/day till the end of November and rainfall is not predicted until the 1st week of December. Eastern Coast – The rainfall shall vary below 2 mm/day till 26th of November and rainfall is not predicted until the 1st week of December. Northern region- The rainfall pattern persisting in the entire country shall be observed in this region with low amount of rainfall. Southern Region- The rainfall pattern persisting in the entire country shall be observed in this region.

Seasonal Prediction: As per IRI Multi Model Probability Forecast issued on October 2013; for November, December 2013 to January 2014, there is a 60-70% probability for temperature to be above normal in the country while the rainfall is to be climatological.

PACIFIC SEAS STATE October 17, 2013 :During September through October the observed ENSO conditions remained neutral. Most of the ENSO prediction models indicate a continuation of neutral ENSO through 2013 & the first quarter of 2014. A long lasting mean disagreement between statistical and dynamical models (statistical leaning cooler, dynamical warmer) has diminished. The average forecast of all models indicates a gradual warming tendency during the first half of the 2014.

INDIAN OCEAN STATE :Southern sea of Sri Lanka showed +10C anomaly and rest of the seas around Sri Lanka showed neutral seas surface temperature during 3rd-9th November 2013.
MJO STATE :MJO is neutral and shall not influence Sri Lanka rainfall.