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Thursday, August 11, 2016

Weekly Hydro-meteorological Report, 11, August 2016

Highlights: Mostly dry weather conditions prevailed in the previous week for the period from 3rd-6th while considerable rainfall was experienced by Badulla district in the last two days. Up to 30 mm of rainfall was recorded in Badulla district close to Arawa on 8th while on 9th considerable rainfall was recorded in several districts in the central region of the country. The lowest temperature was recorded in Nuwara Eliya to be between 15-20 0C while the maximum temperature was recorded in the eastern coastal belt to be between 35-40 0C. Up to 54 km/h westerly and north westerly wind was recorded all over the island. For the week from 11th-17th August rainy weather is expected in the western province and the adjoining sea. Up to 55 km/h north westerly and westerly wind is expected in the southern half of the country..
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Weekly Monitoring:No rainfall was observed in any part of the island on 3rd of August. On 4th less than 5 mm rainfall was observed in Moratuwa and nearby south western sea region. Dry weather conditions prevailed throughout the island on 5th and 6th with only Monaragala and neighboring areas receiving less than 5 mm rainfalls on the 7th. On 8th Rainfall up to 30 mm was observed in the regions of Bible and Migahakiula while Badulla and Badalkumbura received rainfall up to 20 mm. On 9th areas near the border of Baulla, Monaragala and Ampara districts received rainfall between 15-20 mm with Beligalla and Padiyathalawa receving up to 20 mm. For the past week, the RFE 2.0 tool shows rainfall between 10-25 mm in Badulla, Monaragala, Buttala and Padiyathalawa areas. It also shows 10-25 mm below average rainfall in adjacent areas of Colombo, Kalutara, Bentota, Ratnapura and south western and southern sea near the island. Above average rainfall of 10-25 mm is shown in Badulla and Ella areas.

Monthly Monitoring: Considering the dry weather condition that prevailed in the month of June, the rainfall for the month of July was comparatively high. The RFE 2.0 tool shows a total rainfall of ~150 mm in Badulla district and close to Ratnapura and Vavuniya towns and ~100 mm in Kalutara, Nuwara Eliya districts and close to Avissawella, Ellegoda, Wellawaya, Bibila areas and in the south western sea close to Galle and Matara. Rest of the north central, central, western and Sabaragamuwa provinces received up to ~75 mm of total rainfall.

For the period from 31st July-6th August, the lowest temperature was recorded in Nuwara Eliya to be between 15-20 0C. The maximum temperature was recorded from the Eastern coastal belt to be between 35-40 0C. The maximum temperature of Kandy, Colombo, Kurunegala, Galle and Matara areas were 30-35 0C.
Both at 850 mb and 700 mb levels north westerly winds with speed between 36-55 km/h was experienced all over the island and the surrounding sea.

Ocean State
Pacific seas state: July 21, 2016
During mid-July 2016 the tropical Pacific SST anomaly was slightly below zero, indicating ENSO-neutral conditions. The key atmospheric variables also indicate neutral ENSO conditions. This includes near-average upper and lower level tropical Pacific winds, as well as mainly near-normal cloudiness and rainfall patterns in the central and eastern equatorial Pacific. Most ENSO prediction models indicate neutral ENSO conditions during July, with likely development of La Niña during August or September, lasting through fall and into winter. Most likely strength is weak. (Text Courtesy IRI)
Indian Ocean State
Neutral sea surface temperature was observed around Sri Lanka.


14-day prediction: NOAA NCEP models predicts 15-25 mm rainfall in the Northern Province and Trincomalee and close to Horana for the period from 10th-16th August. During the same period rest of the country except eastern province and Hambanthota district may experience slight rainfall. For the period from 17th-23rd August, between 35-45 mm of rainfall is expected close to Trincomalee, between 25-35 mm of rainfall is expected in Colombo, Ratnapura, Matara, Eastern side of Kilinochchi, Mullaitivu districts and adjacent sea and close to Talgaswela and Udugama areas in Galle district while the rest of the country except Puttalam and Mannar shall experience 15-25 mm of rainfall.

Weekly predictionIMD GFS model predicts wet weather conditions in the western province for the week from 11th-17th August. No rainfall is predicted on any part of the island on 11th while on 12th up to 20 mm of rainfall is predicted in the coastal regions of Kalutara district, Bentota area and the surrounding sea. On 13th coastal regions of Colombo and Kalutara, Bentota, Balapitiya and the western sea may experience up to 40 mm of rainfall while the rest of the western province, Gampaha and Galle districts may experience between 10-20 mm of rainfall. On 14th coastal areas of Kalutara, Galle and western side of Matara and sea adjacent to these areas may experience up to 40 mm of rainfall while the rest of the western province, Galle and Matara, Gampaha districts and the adjacent sea may experience 10-20 mm of rainfall. On 15th the intensity of the rainfall is seen to be reduced and only up to 20 mm of rainfall is predicted in the coastal region close to Dehiwala and Moratuwa areas. On 16th Colombo, the western region of Kalutara and the adjacent sea may experience up to 20 mm of rainfall while on 17th up to 20 mm of rainfall is predicted in entire Western province, Galle district and the adjacent sea

IMD WRF Model Forecast & IRI forecast:According to the IMD WRF model, up to 35 mm of total rainfall is predicted in the western province, Kurunegala, Puttalam and Galle districts for the period from 10th-12th August. For the period from 10th-13th, up to 35 mm is predicted in the same region as well as in Kegalle, Matara and eastern side of Ratnapura district. No extreme conditions are predicted for the period from 10-15th August.

 Seasonal Prediction:As per IRI Multi Model Probability Forecast for August to October, the total 3-month precipitation shall be climatological. The 3-month temperature has more than 70-80% likelihood in the entire country of being in the above-normal tercile during this period.

NOAA CPC GFS model predicts 35-40 0C maximum temperature along the coastal belt in the Eastern side of the country, Kilinochchi, Vavuniya and Mullaitivu districts. The maximum temperature of Colombo, Kalutara, Kandy and Galle areas will be between 25-30 0C while that of Kurunegala and Matale districts will be between 30-35 0C. For the same period minimum temperature is expected in Nuwara Eliya to be between 15-20 0C.

The 850 mb level predicts up to 55 km/h north westerly wind in the lower half of the country including Kandy and Moneragala areas while up to 36 km/h westerly wind is predicted in the northern half of the country and Ampara and Batticaloa areas. At 700 mb level Hambantota district may experience up to 36 km/h north westerly wind while the rest of the country may experience up to 28 km/h westerly and north westerly wind.

MJO based OLR predictions
MJO will be in the western Pacific Ocean in the next seven days and shall not have an effect on the rainfall patterns of Sri Lanka.

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