Weekly Hydro-meteorological Report, 28, December 2017

Highlights:

•   The IRI Model predicts total rainfall between 50-75 mm in Kandy, Nuwara Eliya, Badulla, Ratnapura and Monaragala districts during 27th Dec 2017-01st Jan 2018.
•   Between 20 - 25 Dec: Rainfall up to 60 mm was recorded in Hambantota, Nuwara Eliya, Ratnapura and Badulla districts on December 20th.
•   From 17- 23 Dec:  minimum temperature of 15 ^OC was recorded from Nuwara Eliya district while western and southern parts of the island recorded a maximum temperature between  30-35 ^OC.
•   From 19- 25 Dec: up to 36 km/h, northeasterly winds were experienced by the entire island.
•   0.5 ^OC above average sea surface temperature was observed in the southern seas of Sri Lanka.

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Summary

Monitoring

Weekly Monitoring: On December 20th, Hambantota, Nuwara Eliya, Ratnapura and Badulla districts received up to 60 mm of rainfall; Kegalla, Ampara and Monaragala districts up to 50 mm; Batticaloa, Polonnaruwa, Gampaha, Colombo, Kalutara, Matara, Matale and Kandy districts up to 30 mm; Mannar, Vavuniya, Anuradhapura, Puttalam, Kurunegala, Trincomalee and Galle districts up to 20 mm; and rest of the island up to 10 mm. On the 21st Gampaha, Colombo, Kalutara, Ratnapura, Galle and Matara districts received up to 30 mm of rainfall; and Jaffna, Kilinochchi, Nuwara Eliya, Ampara and Monaragala districts up to 10 mm. No significant rainfalls were recorded in any part of the island during 22nd-23rd. On the 24th, Ratnapura district received up to 50 mm of rainfall; and several regions of Kalutara, Matara, Badulla and Monaragala districts up to 20 mm. On the 25th, Jaffna and Kilinochchi districts received up to 20 mm of rainfall. 

Total Rainfall for past week :  The RFE 2.0 tool shows total rainfall of 75-100 mm in Nuwara Eliya, Kegalla, Ratnapura, Badulla and Monaragala districts; up to 50-75 mm in Gampaha, Colombo, Kalutara, Galle, Ampara and Hambantota districts; up to 25-50 mm Matara, Matale, Kandy and Batticaloa districts. It shows above average rainfall up to 50-100 mm in Ratnapura, Badulla, and Nuwara Eliya districts; and up to 25-50 mm in Colombo, Kegalla, Kandy, Monaragala and Hambantota districts. It also shows below average rainfall up to 50-100 mm in Trincomalee, Polonnaruwa, Batticaloa and Ampara districts; and up to 25-50 mm in Mannar, Mullaitivu, Kilinochchi, Mullaitivu, Vavuniya, Anuradhapura and Matale districts.

Monthly Monitoring: During November - below average rainfall conditions were experienced in the western and central regions of the island and above average rainfall in northern, southern and eastern regions. Kurunegala, Puttalam, Anuradhapura, Polonnaruwa, Matale, and Vavuniya districts received up to 180 mm below average rainfall. Galle, Matara, Ratnapura, Hambantota, Badulla, Monaragala and Ampara districts received up to 180 mm of above average rainfall. The CPC Unified Precipitation Analysis tool shows ~500 mm of total rainfall in Colombo, Ratnapura, Galle, Matara, Hambantota, Badulla, Monaragala and Ampara districts; up to ~300 mm in Jaffna, Trincomalee, Matale, Kandy, Nuwara Eliya, Kegalla and Polonnaruwa districts.

Predictions

14-day prediction:
NOAA NCEP Models:

From 27th Dec 2017 – 02nd Jan 2018: Total rainfall between 65-75 mm in Ratnapura, Matara, Hambantota, Monaragala and Ampara districts; between 55-65 mm in Galle and Badulla districts; between 45-55 mm in Kalutara and Nuwara Eliya districts; between 25-35 mm in Colombo, Gampaha, Kegalle, Kandy and Batticaloa districts; Up to 5 mm total rainfall rest of the island.

From 03rd Jan – 09th Jan: Total rainfall between 65-75 mm in Hambantota, Monaragala, Badulla and Ampara districts; between 55-65 mm in Galle, Matara and Ratnapura districts; between 45-55 mm in Nuwara Eliya and Batticaloa districts; between 35-45 mm in Colombo, Kegalle and Kandy districts; between 25-35 mm in Gampaha, Matale and Polonnaruwa districts; between 15-25 mm in Puttalam, Kurunegala and Trincomalee districts; Up to 15 mm total rainfall rest of the island.

IMD WRF Model Forecast: 

29th Dec: Up to 7.6 mm of rainfall in Hambantota, Monaragala, Badulla, Ampara, Batticaloa, Trincomalee, Polonnaruwa, Anuradhapura, Vavuniya and Mullaitivu districts; Up to 2.5 mm in Jaffana, Kilinochchi, Mannar, Puttalam, Matale, Kandy, Gampaha, Colombo, Kalutara,  Galle and Matara districts.

30th Dec: Up to 7.6 mm of rainfall in Hambantota, Monaragala, Ampara, Kilinochchi and Mullaitivu districts; Up to 2.5 mm in Colombo, Kalutara, Jaffna, Mannar, Vavuniya, Puttalam, Anuradhapura, Trincomalee, Polonnaruwa and Batticaloa districts.

IRI Weekly forecast:
27th Dec 2017– 1st Jan 2018: Total rainfall between 50-75 mm in Kandy, Nuwara Eliya, Badulla, Ratnapura and Monaragala districts; between 25-50 mm in Matale, Kurunegala, Gampaha, Kegalle, Colombo, Kalutara, Galle, Matara, Hambantota, Ampara, Batticaloa and Polonnaruwa districts; Up to 25 mm total rainfall rest of the island.


Ocean State (Text Courtesy IRI)
PACIFIC SEAS STATE : December 19, 2017

In mid-December 2017, the tropical Pacific reflected La Niña conditions, with SSTs in the east-central tropical Pacific in the range of weak to moderate La Niña and all atmosphere variables showing patterns suggestive of La Niña conditions. The collection of latest ENSO prediction models indicates weak, but not far from threshold of moderate, La Niña as the most likely scenario for the Northern Hemisphere winter, lasting into spring. The official CPC/IRI outlook favors continuation of La Niña through middle or late spring.

INDIAN OCEAN STATE :   0.5 ^OC above average sea surface temperature was observed in the southern seas of Sri Lanka.

MJO STATE :  MJO shall not have impact on the rainfall in Sri Lanka in the next 5 days and shall enhance the rainfall in following 10 days.