Weekly Hydro-meteorological Report, 24 May 2012

Summary

Monitoring 

Weekly Monitoring: During the week of 15th May-21st May rainfall ranged between 0-10 mm. During 15th-17th no rainfall was observed for the entire country. However during 18th-21st May there was rainfall compared to the period of 15th-17th, but rainfall was observed for the scattered places over Sri Lanka. 

Monthly Monitoring: During April, the entire island has shown an above average rainfall. 

Predictions 

7 Day Prediction: During next week, an accumulated rainfall of 5 mm -55 mm is predicted for the South-western regions of the island. 

IMD WRF Model Forecast & IRI forecast: For the 26th May 2012, WRF Model Predicts less than 65 mm rainfall for Kalutara and Colombo districts and rainfall shall spreads towards Gampaha, Kegalle, Ratnapura and Galle districts in a reducing pattern. On 27th May, less than 36 mm rainfall is predicted for the Kalutara and Colombo districts and 8 mm rainfall is predicted for the Gampaha and Ratnapura. IRI models forecast less than 25 mm, 45-75 mm and 25-45 mm of rainfall for the Northern, Southern and in between regions of Sri Lanka, respectively. 

1 Month Prediction: Overall, from 24th-26th May 2012, rainfall shall increase and then it shall decrease gradually till the 2nd June. There onwards rainfall shall increase gradually with minor fluctuation between 5th -8th June followed by a gradual increase till the 20th June. Western Slopes- Rainfall received for western slopes is high compared to the other regions of Sri Lanka. A rapid increase of rainfall shall be expected duing 24th-26th May and shall decrease gradually till 8th June with minor peaks on 29th May and 4th June. There onwards ranfall shall increase gradually. Eastern Slopes- Rainfall shall decrease gradually during 24th May-7th June and shall increase gradually therefter. Northern Region- Rainfall shall increase during 24th-26th and shall decrease till 31st May. Rainfall shall shows constant during 31st May-5th June 2012 and threafter rainfall shall increase gradually. 

Seasonal Prediction: As per IRI Multi Model Probability Forecast for June 2012 to August 2012, issued in May 2012, there is a 45%-50% probability for temperature to be above normal for the country. There is 40% probability for rainfall to be climatological. 

Inside this Issue 

1. Monitoring 

a. Daily Satellite Derived Rain fall Estimates 

b. Monthly Rain fall Estimates 

c. Decadal (10 Day) Satellite Derived Rainfall Estimates 

d. Weekly Average SST Anomalies 

2. Predictions 

a. NCEP GFS Ensemble 1-7 day predictions, NOAA, CPC,USA 

b. IMD WRF Model Forecast 

c. Weekly precipitation forecast (IRI) 

d. 1 month experimental predictions by Paul Roundy and L. Zubair 

e. Seasonal Predictions from IRI 

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