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Friday, July 13, 2012

Weekly Hydro-meteorological Report, 12 July 2012



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.

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.

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

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