Weekly Hydro-meteorological Report, 28, February 2018

Highlights:

•   The IRI weekly forecast predicts total rainfall between 75-100 mm in Nuwara Eliya, Badulla and Kandy districts during 27th Feb - 4th Mar. 
•   Between 20-26 Feb: up to 90 mm of rainfall was recorded in Matara district on the 26th.
•   From 11-17 Feb:  minimum temperature of 15 ^OC was recorded from Nuwara Eliya district while Gampaha, Kurunegala and Colombo districts  recorded a maximum temperature between  30-35 ^OC.
•   From 19-25 Feb: up to 18 km/h, northeasterly winds were experienced by the entire island.
•   0.5 ^OC below average sea surface temperature was observed in the northern seas of Sri Lanka.

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Summary

Monitoring

Weekly Monitoring: No significant rainfalls were recorded in any part of the island during February 20-23. On February 24th, Ampara district and northern regions of Monaragala district received up to 80 mm of rainfall; Badulla district received up to 50 mm; Batticaloa district up to 30 mm; and several regions of Kandy, Trincomalee and Polonnaruwa districts up to 20 mm. On the 25th, Ampara and Polonnaruwa districts received up to 50 mm of rainfall; Colombo, Kalutara, Badulla, Trincomalee, Batticaloa and Matale districts up to 30 mm; Mullaitivu, Gampaha, Kandy and Monaragala districts up to 20 mm; and many central and southern regions of the island up to 10 mm. On the 26th, Matara district received up to 90 mm of rainfall; Hambantota district up to 60 mm; Kalutara, Galle, Matale and Polonnaruwa districts received up to 50 mm; Batticaloa district up to 40 mm; Ampara and Ratnapura districts up to 30 mm; Trincomalee, Puttalam, Gampaha, Colombo, Kalutara, Kandy, Nuwara Eliya and Monaragala districts up to 20 mm.

Total Rainfall for past week :  The RFE 2.0 tool shows total rainfall of 75-100 mm in Polonnaruwa, Matale, Ampara, Badulla and Monaragala districts; up to 50-75 mm in Trincomalee, Batticaloa, Galle and Matara districts; and up to 25-50 mm in Colombo, Kalutara, Ratnapura, Kandy, Anuradhapura, Kurunegala and Hambantota districts. It also shows above average rainfall up to 50-100 mm in Matale, Polonnaruwa, Anuradhapura, Badulla, Monaragala, Ampara, Galle and Matara districts; and up to 25-50 mm in Colombo, Kalutara and Kandy districts. Below average rainfall up to 25-50 mm is shown for Kurunegala district.

Monthly Monitoring: During January - below average rainfall conditions were experienced by the entire island. Trincomalee, Polonnaruwa, Batticaloa, Matale, Colombo, Kalutara, Galle, Ratnapura, Badulla, Monaragala and Ampara districts received up to 180 mm below average rainfall; and rest of the island up to 120 mm. The CPC Unified Precipitation Analysis tool shows ~100 mm of total rainfall in Puttalam, Kalutara, Nuwara Eliya and Badulla districts; and up to ~75 mm in Anuradhapura, Kurunegala, Gampaha, Kegalla, Ratnapura, Galle, Matara, Matale, Kandy, Monaragala and Ampara districts. 

Predictions

14-day prediction:
NOAA NCEP Models:

From 27th Feb – 05th Mar: Total rainfall between 45-55 mm in Colombo, Kegalle, Kandy, Nuwara Eliya, Badulla, Monaragala, Ratnapura, Galle and Matara districts; between 35-45 mm in Gampaha, Kurunegala, Matale, Ampara and Hambantota districts; between 25-35 mm in Puttalam, Polonnaruwa and Batticaloa districts; between 15-25 mm in Anuradhapura and Trincomalee districts; Up to 15 mm of total rainfall rest of the island.

From 06th – 12th Mar: Total rainfall between 35-45 mm in Badulla, Ampara and Monaragala districts; between 25-35 mm in Polonnaruwa, Matale, Batticaloa, Kandy, Nuwara Eliya, Ratnapura, Kegalle, Gampaha and Colombo districts; Up to 15 mm total rainfall rest of the island.

IMD WRF Model Forecast: 

1st Mar: Up to 35.6 mm of rainfall in Ampara and Batticaloa districts; Up to 7.6 mm of rainfall in Mullaitivu, Vavuniya, Trincomalee, Anuradhapura, Polonnaruwa, Monaragala, Hambantota, Galle, Badulla, Kandy and Matale districts; Up to 2.5 mm in Jaffna, Mannar, Puttalam, Gampaha, Colombo, Kalutara, Matara, Ratnapura and Nuwara Eliya districts.

2nd Mar: Up to 35.6 mm of rainfall in Ampara, Monaragala and Hambantota districts; Up to 7.6 mm in Mullaitivu, Vavuniya, Anuradhapura, Trincomalee, Polonnaruwa, Batticaloa, Galle, Kurunegala, Kegalle and Kandy districts; Up to 7.6 mm of rainfall in rest of the island.

IRI Weekly forecast:
From 27th Feb – 4th Mar: Total rainfall between 75-100 mm in Nuwara Eliya, Badulla and Kandy districts; between 50-75 mm in Puttalam, Kurunegala, Matale, Ampara, Monaragala, Ratnapura, Kalutara, Colombo, Gampaha and Kegalle districts; between 25-50 mm in Anuradhapura, Polonnaruwa, Trincomalee, Batticaloa, Hambantota, Matara and Galle districts; Up to 25 mm total rainfall rest of the island.


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

In mid-February 2018, 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 most key atmospheric variables showing patterns suggestive of La Niña conditions. The official CPC/IRI outlook calls for La Niña continuing through at least early spring, followed by a likely return to neutral conditions around mid-spring. Support for this scenario is provided by the latest forecasts of statistical and dynamical models.

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

MJO STATE :  MJO shall enhance the rainfall in Sri Lanka.