Weekly Hydro-meteorological Report, 21 February 2013

Highlights

Monitoring and Prediction
Except for the eastern coastal belt of Sri Lanka, there shall be no rainfall for the period from 20th-26th February. Certain parts of Batticaloa and Ampara districts shall receive rainfall less than 2.5 mm, on the 22nd & 23rd February 2013. However a drastic drop in rainfall shall be experienced during 21st-23rd and shall gradually increase thereafter.

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Summary

Monitoring


Weekly Monitoring:Rainfall ranged between 5-145 mm during 13th-19th February 2013. Maximum rainfall was observed on the 13th February in the eastern boundary of the Hambantota district. Dry conditions prevailed throughout the country on the 15th of February.

Predictions

7-day prediction:Eastern coastal belt of Sri Lanka shall receive 0-35 mm of rainfall during 20th-26th February, and no rainfall is recorded for the rest of the country.

IMD WRF Model Forecast & IRI forecast:For 22nd of February 2013, IMD WRF model predicts less than 2.5 mm of rainfall for a small area in the Batticaloa district, and less than 1 mm of rainfall for the entire country. For the 23rd of February, IMD WRF model predicts less than 1 mm of rainfall for the entire country, and less than 2.5 mm rainfall for a small area in the Ampara district. NOAA model predicts rainfall for the Southern 1/3rd of the country from 20th– 25th February.

1 Month Prediction: Overall- Existing rainfall shall drop during 21st-23rd February. Thereafter rainfall shall increase gradually till 4th March. Western Slopes – Existing rainfall shall drop drastically (10 mm/day to 2 mm/day) during 21st-23rd February. Thereafter rainfall shall increase gradually to more than 10 mm/day during 23rd February-6th March. Western Coast - Existing rainfall shall reach more or less 0 mm/day on 22nd and shall increase gradually till it reaches 8 mm/day. Eastern slopes & Eastern Coast – The rainfall pattern existing in the entire country shall be present in these two regions. Northern region- Constant amount of rainfall shall persist throught last two weeks of February. Southern Region- The rainfall pattern existing in the entire country shall be present in this region.

Seasonal Prediction:As per IRI Multi Model Probability Forecast issued on January 2013; for February 2013 to April 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 February 7, 2013 :Most of the ENSO prediction models predict natural ENSO conditions through the first half of 2013. During January the observed SST conditions have become below average, but in the neutral range.

INDIAN OCEAN STATE :In the Pacific, the El Nino state has weakened to neutral although there is weak warming remnant in the El Nino index areas. The unusually warmer sea surfaces of the Arabian Sea/Central Western and South-Eastern Indian Ocean remain.