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Thursday, December 29, 2016

Weekly Hydro-meteorological Report, 29, December 2016


  •  The IMD WRF model predicts rainfall up to 35 mm on 30th December in northern and eastern parts of the island.  
  •  Between Dec 20–26: highest rainfall of 50 mm was recorded on the 26th in the surrounding regions of Padawiya in Anuradhapura district.
  •  From Dec 18–24: minimum temperature of 15 OC was recorded from Nuwara Eliya district while many parts of the island recorded a maximum temperature between 30-35 OC.
  •  From Dec 20–26: up to 18 km/h north easterly winds were experienced by the entire island.

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Weekly Monitoring: On December 20th Padukka, Labugama regions in Colombo district and Ratnapura town area received up to 20 mm of rainfall. During the period 21st-25th Dec no significant rainfalls were recorded in any part of the island. On 26th Vavuniya and Anuradhapura districts received up to 50 mm of rainfall; Mullaitivu, Trincomalee, Polonnaruwa, Batticaloa and Ampara districts up to 30 mm; and Kilinochchi district received up to 20 mm of rainfall.

Total Rainfall for past week : The RFE 2.0 tool shows total rainfall up to 75 mm for Vavuniya district and for the coastal regions of Colombo district; up to 50 mm for Jaffna, Mullaitivu, Anuradhapura, Polonnaruwa, Trincomalee, Batticaloa, Ampara and Badulla districts; and up to 25 mm for many parts of the island. It shows above average rainfall of 100-200 mm for the coastal regions of the Colombo district; 25-50 mm for the eastern regions of Vavuniya district; below average rainfall of 25-50 mm for Mannar, Anuradhapura, Polonnaruwa, Trincomalee, Batticaloa, Ampara, Monaragala, Hambantota, Matara, Galle, Kurunegala and Puttalam districts; and 10-25 mm for rest of the island.

Monthly Monitoring:During November - above average rainfall conditions were experienced in Jaffna, Kilinochchi, Kegalla, Gampaha, Colombo, Galle, Matara and several regions of Kurunegala and Puttalam districts. 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:
NOAA NCEP Models: From 28th Dec – 3rd Jan: Total rainfall up to 55 mm for the eastern coastal regions of Hambantota district; 35-45 mm for Ampara district; 25-35 mm for Monaragala and Matara districts; and 15-25 mm in Badulla, Galle and eastern regions of Ratnapura districts.
From 4th – 10th January: Total rainfall between 25-35 mm is expected in the eastern coastal regions of Hambantota district; and 15-25 mm in Ampara, Monaragala, and Matara districts.

IMD WRF Model Forecast & IRI forecast: Up to 35 mm of rainfall is expected on the 30th in Mannar, Vavuniya, Trincomalee, Anuradhapura, Batticaloa and Ampara districts; and up to 7 mm of rainfall in many parts of the island. On the 31st, Batticaloa, Ampara and northern regions of Badulla and Monaragala districts will receive up to 30 mm of rainfall and rest of the eastern coastal regions will receive up to 7 mm of rainfall.

Seasonal Prediction: As per IRI Multi Model Probability Forecast for January to March 2017, the total 3-month precipitation has 40-50% likelihood of being in the above-normal tercile 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 : December 15, 2016
During mid-December 2016 the tropical Pacific SST anomaly was near -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, although subseasonal atmospheric variability weakened some of them in late November. 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 the threshold of La Niña persisting through mid-winter, then weakening to cool-neutral by later winter.

INDIAN OCEAN STATE : Sea surface temperature was climatological in the seas around Sri Lanka.

MJO STATE : For the next 15 days: MJO shall suppress the rainfall in Sri Lanka.

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