Weekly Hydro-meteorological Report, 10 January 2013

Highlights

Monitoring and Prediction
Heavy rainfall shall diminish during 9th-15th January for the entire country. However, significant amount of rainfall shall be received for the southern 2/3rd of Sri Lanka during 8th-13th January. The monthly predictions point to an Extreme amount of rainfall for the entire country around 22nd-24th. Extreme rainfall shall persist from 22nd till end of January.

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Summary

Monitoring


Weekly Monitoring: From 4th-8th January 2013, rainfall ranged between 5-185 mm with the highest amount of precipitation observed in the Anuradhapura district on the 7th of January. On 7th January entire country received rainfall between 20-185 mm. During 4th-6th the South-eastern half and eastern regions received heavy rainfall. On 8th the Northern half of Sri Lanka received heavy rainfall.

Predictions

7-day prediction: During the period 9th-15th January 2013, Southern regions shall receive 5-25 mm of rainfall. For the same period, North and middle stretch of the island shall receive 25-55 mm of rainfall, and 55-75 mm of rainfall can be expected for the North-eastern regions.

IMD WRF Model Forecast & IRI forecast:For the 11th of January 2013, IMD WRF model predicts less than 65 mm of rainfall for Batticaloa and Ampara districts. Rainfall shall spread towards the westward direction with a decreasing trend. For the same day the model predicts 8-36 mm of rainfall for Matara, Galle and Kalutara districts. The stretch which combines Monaragala, Badulla and Ratnapura districts and, Gampaha Colombo and Kegalle districts shall receive less than 1 mm of rainfall. On 12th of January 2013, IMD WRF model predicts 8-36 mm of rainfall for Galle, Batticaloa and Ampara districts. Except for South-western districts, Galle, Matara, Eastern and South-eastern regions, entire Sri Lanka shall receive less than 1 mm of rainfall. NOAA models forecast heavy rainfall for the Southern 2/3rd of the island and very heavy rainfall for South-eastern regions of the island from 8-13th January 2013.

1 Month Prediction: Overall- Extreme rainfall is expected for the entire country around 22nd-24th. More or less heavy rainfall shall persist from 22nd- till end of January. Western Slopes- When compared to the rest of the regions, western slopes shall receive higher amount of rainfall. During the month of January, extreme daily rainfall of 17 mm and 15 mm are expected around the 22nd-24th and end of January. Western Coast- Same pattern shall exist for the entire country. Eastern slopes- Comparative amount of daily rainfall (6 mm) shall be received during the period 22nd-25th. Eastern Coast- Extreme amount of rainfall shall be received around 15th-16th and 22nd-24th and end of January. Northern region- Extreme rainfall of 5 mm/day shall persist during 22nd-30th. Southern region - Extreme rainfall shall be received around 21st-24th.

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, 2012 : Most 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 : During January 2013, warmer SST shall be over tropical Indian Ocean than the Bay of Bengal which shall aggravate unusual weather patterns.