Weekly Hydro-meteorological Report, 24 October, 2013

Highlights

Monitoring and Prediction
Rainfall shall increase during 24th-27th and is likely to decrease gradually till the end of month (October 2013). However, significant rainfall event is likely to observer around 26th-28th October for the western slopes. Heavy rainfall is likely to observe for the southwestern regions and northeastern regions during coming two days (26th & 27th October).

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Summary

Monitoring


Weekly Monitoring:During 15th-22nd October 2013, rainfall ranged between 5 – 90 mm/day. Entire country received rainfall on 18th October. However, the island was comparatively wetter than the September 2013.


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

Predictions

7-day prediction:Southwestern regions shall receive rainfall of less than 75 mm/day and shall spread towards North-east direction in a reducing pattern during 23rd-29th October 2013.

IMD WRF Model Forecast & IRI forecast:For 26th of October, IMD WRF model predicts less than 36 mm of rainfall for Kalutara-Hambantota, Ratnapura and Trincomalee districts and shall spread to nearby districts in a reducing manner. For 27th of October, model predicts less than 65 mm/day of rainfall for Galle district and shall spread to nearby districts in a reducing manner. However, NOAA model predicts more rainfall for Northeastern regions of Sri Lanka during 23rd-28th October 2013.

1 Month Prediction:Overall- Rainfall shall increase during 24th-27th and is likely to decrease gradually till the end of month (October 2013). Thereafter rainfall shall vary between 2-5 mm/day. Western Slopes – The rainfall pattern persisting in the entire country shall be observed in this region with high amount of rainfall. However, significant rainfall event is likely to observer around 26th-28th October. Western Coast – The rainfall pattern persisting in the western slopes shall be observed in this region. Eastern Slopes– Rainfall is likely to decrease gradually till the end of month (October 2013). Thereafter rainfall shall vary between 1-4 mm/day. Eastern Coast – Rainfall is likely to decrease gradually till the end of month (October 2013). Thereafter rainfall shall vary between 1-4 mm/day. However, rainfall is not predicted during 28th Ocotber-2nd November 2013. Northern region- The rainfall pattern persisting in the Eastern slopes shall be observed in this region. 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 July 18, 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 :The sea surface temperature around Sri Lanka was neutral during 13th-19th October 2013.
MJO STATE :MJO is neutral and not influences Sri Lanka rainfall.