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Thursday, December 8, 2016

Weekly Hydro-meteorological Report, 8, December 2016


  •  The IMD WRF model predicts rainfall up to 64 mm on 9th December for coastal regions of Batticaloa district.  
  •  Between Nov 30 & Dec 6, the highest rainfall of 50 mm was recorded on the 30th in Jaffna, Kilinochchi and Mannar districts.
  •  From Nov 27 – Dec 3, Minimum temperature of 15 OC was recorded from Nuwara Eliya district while most parts of the island recorded a maximum temperature between 30-35 OC.
  •  From Nov 29 – Dec 5, up to 18 km/h north easterly winds were experienced in Jaffna, Kilinochchi and Mullaitivu regions while rest of the island experienced north westerly wind with speeds less than 10 km/h.

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Weekly Monitoring: On November 30th Jaffna, Kilinochchi and Mannar districts received rainfall up to 50 mm; Mullaitivu, Vavuniya, Puttalam and Anuradhapura districts up to 30 mm; Kurunegala, Batticaloa, and Trincomalee districts up to 20 mm; and adjacent eastern sea up to 140 mm. On 1st of December Jaffna district including Mannar island received rainfall up to 50 mm; Kilinochchi district including Kekirawa region up to 30 mm; Mullaitivu district and several regions of Vavuniya district up to 20 mm. Up to 90 mm rainfall was received by north western sea on the 2nd. No significant rainfalls were recorded in any part of the island on the 2ndor 3rd. On 4th up to 50 mm rainfall was received by Galle, Matara, Ratnapura, Kalutara districts and up to 20 mm rainfall by several regions of Colombo, Hambantota and Kurunegala districts. Galle and adjacent sea region received up to 20 mm rainfall on the 5th. No significant rainfalls were recorded on the 6th.

Total Rainfall for past week : The RFE 2.0 tool shows total rainfall up to 100 mm in Kilinochchi and Jaffna regions; up to 50 mm for Kalutara, Ratnapura, Galle, Matara, Mannar, Vavuniya, Mullaitivu and Anuradhapura regions; up to 25 mm for Puutalam, Kurunegala, Polonnaruwa and Colombo regions. It shows below average rainfall of 10-25 mm for south western and northern regions of the country and below average rainfall of 25-50 mm for the rest of the island.

Monthly Monitoring:Above average rainfall conditions were experienced in Jaffna, Kilinochchi, Kegalla, Gampaha, Colombo, Galle, Matara and several regions of Kurunegala and Puttalam districts during November. Monthly average rainfall for these regions amounted to 360 mm/month. Rest of the island experienced below average rainfall conditions with a monthly average not exceeding 180 mm/month. The CPC Unified Precipitation Analysis tool shows ~300 mm of total rainfall in, Kilinochchi, Mullaitivu, Gampaha, Colombo, Ratnapura, Batticaloa, Kalutara, Hambantota, Galle and Matara districts; ~200 mm in Vavuniya, Mannar, Anuradhapura, Polonnaruwa, Puttalam, Kurunegala, Kegalla and Monaragala districts; and 150 mm in rest of the island.


14-day prediction:
From 7th – 13th December, the NOAA NCEP models predicts total rainfall up to 55 mm for coastal regions of Colombo, and Hambantota and several regions of Ratnapura and Matara districts; 35-45 mm in Gampaha and Kegalla districts; 25-35 mm in Nuwara Eliya district; and 65-75 mm in western and southern sea regions adjacent to the island.

From 14th – 20th December, total rainfall between 25-35 mm is expected in Colombo and 15-25 mm in Ratnapura, Galle, Matara and Hambantota districts.

IMD WRF Model Forecast & IRI forecast:: According to the IMD WRF model, up to 64 mm of rainfall is expected on the 9th in coastal regions of Batticaloa; up to 35 mm of rainfall in rest of Batticaloa, Anuradhapura, Polonnaruwa and Matale districts; and up to 7 mm in most parts of the island. On the 10th, Hambantota, Embilipitiya, Balangoda, and Kataragama regions will receive up to 7 mm of rainfall; and a decreasing tendency of rainfall is expected throughout the country.

Seasonal Prediction:As per IRI Multi Model Probability Forecast for December to February 2017, the total 3-month precipitation shall be climatological for the whole island. The 3-month temperature has more than 70-80% likelihood in the entire country of being in the above-normal tercile during this period.

Ocean State (Text Courtesy IRI)
PACIFIC SEAS STATE : November 17, 2016
During mid-November 2016 the tropical Pacific SST anomaly was slightly cooler than -0.5C, the threshold for weak La Niña. Also, most of the atmospheric variables across the tropical Pacific have been consistent with weak La Niña conditions. The upper and lower atmospheric winds have been suggestive of a strengthened Walker circulation, and the cloudiness and rainfall have also been consistent with weak La Niña conditions. The collection of ENSO prediction models indicates SSTs near or slightly cooler than the threshold of La Niña during the remainder of fall, persisting through mid-winter, then weakening to cool-neutral by later winter.

INDIAN OCEAN STATE :0.5 OC above average sea surface temperature was observed in the south western and north eastern seas of Sri Lanka.  

MJO STATE :For the next 15 days, MJO shall enhance the rainfall in Sri Lanka during the next 5 days and shall not have a significant impact on rainfall for the following 5 days. MJO shall suppress the rainfall for the succeeding 5 days.

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