Weekly Hydro-meteorological Report, 12 July 2012

Summary

Monitoring

Weekly Monitoring: During the last week (4th June- 9th July) rainfall ranged between 0 mm - 95 mm. South and

Central regions of the island received light rainfall on the 4th, 5th & 7th of July while rainfall was observed in

North Central and Central regions on the 6thof July. Heavy rainfall was observed in South Eastern region of the

island on 8th of July and Central to Western regions on 9th of July.

Monthly Monitoring: During June, parts of Puttalam, Mannar, Kilinochchi, Jaffna, Anuradhapura and

Trincomalee districts experienced above average rainfall, up to a surplus of 20 mm. The rest of the country

experienced below average rainfall.

Predictions

7 Day Prediction: For the coming week an accumulated rainfall of 5 - 55 mm is predicted for the South Western

and Northern regions of the island.

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IMD WRF Model Forecast & IRI forecast: WRF Model Predicts 35- 125 mm rainfall particularly for Gampaha,

Colombo, and Kalutara districts and 2.5-35 mm rainfall for Galle, Matara districts and Central to Eastern

regions of the country on the 13th of July. For the 14th of July, the Model predicts a slight reduction in the

rainfall, having a similar pattern as the previous day. NOAA models forecast up to 20 mm of rainfall for the

entire island.

1 Month Prediction: Overall a rapid increase in rainfall 10th-13th of July. Then it shall remain the same for a

brief period and then decrease gradually till the 27th of July with minor fluctuations during 20th- 24th of July.

There onwards it shall increase gradually. Western slopes- Nearly the same pattern shall be expected with

increased rainfall. Rainfall shall decrease gradually till 27st July with minor fluctuations between 16th and 24th of

July. Thereafter it shall increase gradually. Eastern slopes- Rainfall shall gradually decrease with minor

fluctuations between 13th and 26th of July. Then it shall increase afterwards. Northern region- Rainfall shall

increase slightly during 10th -13th of July. Then it shall decrease until 20th of July. Between 20th of July and 2nd of

August rainfall shall remain the same with minor fluctuations. Thereafter it shall increase.

Seasonal Prediction: As per IRI Multi Model Probability Forecast for July 2012 to September 2012, issued in

June 2012, there is a 45%-50% probability for temperature to be above normal in the country. There is 40%

probability for rainfall to be climatological.

Experimental Climate Monitoring and Prediction

(Prepared for the Water Management Secretariat of the Mahaweli Authority)

by: Prabodha Agalawatte, Sewwandhi Chandrasekara, Madhura Weerasekera, , Sanjaya Ratnayake, Zeenas Yahiya,

Lareef Zubair and Michael Bell (FECT and IRI1)

12 July 2012

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

International