Weekly Hydro-meteorological Report, 03 January 2013

Highlights

Monitoring and Prediction
Rainfall accumulation of more than 135 mm is expected for the 2nd-8thJanuary for the entire country. 1/3rd of Southern Sri Lanka shall receive extremely heavy rainfall, and heavy showers shall be experienced in the remaining regions of Sri Lanka. The monthly predictions point to significantly high rainfall on the 22nd of January for the entire country, however considerable amount of rainfall shall persists during the month of January for entire Sri Lanka.

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Summary

Monitoring


Weekly Monitoring: From 24th December 2012-1st January 2013, rainfall ranged between 5-145 mm with the highest amount of precipitation observed in the Galle district on the 25th of December. During 24th-27th more or less the entire country received heavy rainfall compared to the period of 25th December-1st January 2013.

Predictions

7-day prediction: During the period 2nd-8th January 2013, the entire country shall receive more than 135 mm rainfall.

IMD WRF Model Forecast & IRI forecast: For the 5th of January 2013, IMD WRF model predicts less than 36 mm of rainfall for Batticaloa and Polonnaruwa districts. Rainfall shall spread with a decreasing trend towards northern parts of Sri Lanka. For the same day less than 2.5 mm of rainfall is predicted for the Galle district. For the 6th of January 2013, less than 8 mm of rainfall is predicted for Batticaloa, Ampara and Badulla districts. NOAA models forecast extremely heavy rainfall for the southern part of the country and very heavy rainfall for the remaining regions.

1 Month Prediction: Overall- Ongoing heavy rainfall shall persist till 5th January 2013 and rainfall shall decrease during 5th-10th. Rainfall shall increase on the 22nd and an extreme amount of rainfall is expected for the entire country. Western Slopes- When compared to rest of the regions, western slopes shall receive higher amount of rainfall. During the month of January, the heaviest daily rainfall of 18 mm is expected on the 22nd of January. Western Coast- Rainfall shall remain constant for the period of 2nd-20th January and vary in the range between 5-9 mm. The heaviest rainfall of the month is expected on the 22nd. Eastern slopes- Significant heavy rainfall is not predicted for this region, but there shall be a significant increase in the rainfall on the 22nd. Eastern Coast- Compared with the eastern slopes more rainfall shall be observed for this season with a similar rainfall pattern. Northern & Southern- Significant heavy rainfall is not predicted for these regions, but there shall be a significant increase in the rainfall on the 22nd.

Seasonal Prediction:As per IRI Multi Model Probability Forecast for January 2013 to March 2013, issued in December 2012, 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 December 20, 2012Most of the ENSO prediction models predict natural ENSO conditions through the first half of 2013. During early December the observed SST conditions have been in the neutral range.

INDIAN OCEAN STATE January 4th-5th, 2013During January 4th-5th 2013, SST shall be warmer over tropical Indian Ocean than the Bay of Bengal.