Weekly Hydro-meteorological Report, 25, October 2018

Highlights:

•   The IRI weekly rainfall forecast predicts total rainfall up to 200 mm in Kandy, Badulla and Nuwara Eliya districts during 24 - 29 Oct.
•   Between 17 – 22 Oct: up to 90 mm of rainfall was recorded in Colombo district on the 22nd.
•   From 14 – 20 Oct: entire island recorded a minimum temperature between 20-25 ^OC and a maximum temperature between  30-35 ^OC.
•  From 16 - 22 Oct: up to 11 km/h, northwesterly winds were experienced by the entire island.
•   0.5 ^OC above average sea surface temperature was observed in the seas around Sri Lanka.

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Summary

Monitoring

Weekly Monitoring: On October 17th, Anuradhapura and Kurunegala districts received up to 30 mm of rainfall; and Jaffna, Kilinochchi, Mullaitivu, Mannar, Vavuniya, Puttalam, Trincomalee, Kegalle, Kandy and Nuwara Eliya districts up to 20 mm.  On the 18th, Jaffna district received up to 30 mm of rainfall; and Kilinochchi district up to 20 mm. On the 19th, Kegalle district received up to up to 50 mm rainfall; Kurunegala, Gampaha, Ratnapura, Kandy, Nuwara Eliya, Badulla and Monaragala districts up to 30 mm; and Puttalam, Matale, Colombo and Kalutara districts up to 20 mm. On the 20th, Puttalam, Kurunegala, Matale, Kandy and Badulla districts received up to 20 mm of rainfall; and most parts of the island up to 10 mm. On the 21st, Kurunegala, Matale, Polonnaruwa, Ampara, Kandy, Nuwara Eliya, Kegalle, Badulla and Monaragala districts received up to 20 mm of rainfall; and most parts of the island up to 10 mm. On the 22nd, Colombo district received up to 90 mm of rainfall; Kalutara and Galle districts up to 80 mm; Puttalam, Kurunegala, Vavuniya, Kandy, Badulla, Kegalle, Ratnapura, Nuwara Eliya and Monaragala districts; up to 30 mm in Anuradhapura, Ampara and Matara districts; and rest of the island up to 20 mm. 

Total Rainfall for past week :  The RFE 2.0 tool shows total rainfall up to 100-150 mm of total rainfall in Badulla and Monaragala districts; up to 75-100 mm in Puttalam, Kurunegala, Kandy, Nuwara Eliya, Kegalle, Ratnapura, Gampaha, Colombo and Kalutara districts; up to 50-75 mm in Anuradhapura, Galle, Matara and Polonnaruwa districts; and up to 50 mm in most parts of the island. Above average rainfall up to 50-100 mm is shown for Monaragala district; and up to 25-50 mm in Badulla, Nuwara Eliya and Kandy districts. Below average rainfall up to 50-100 mm is showan for Mannar, Kurunegala and Anuradhapura districts; up to 25-50 mm for Jaffna, Kilinochchi, Vavuniya, Mullaitivu, Trincomalee, Polonnaruwa, Batticaloa, Kalutara, Galle and Matara districts.

Monthly Monitoring: During September - above average rainfall conditions up to 210 mm were experienced by Ratnapura, Monaragala, Badulla, Kandy, Anuradhapura districts and north eastern regions of Kurunegala district; and up to 60 mm in Mannar, Vavuniya, Puttalam, Matale, Polonnaruwa, Kalutara, Galle and several regions of Matara and Ampara districts. Mullaitivu, Trincomalee, Batticaloa, Gampaha, Colombo and south western regions of Kurunegala district experienced below average rainfall up to 90 mm. The CPC Unified Precipitation Analysis tool shows up to 300 mm of total rainfall in Ratnapura, Kalutara and Galle districts; and up to 200 mm in Anuradhapura, Kurunegala, Kandy, Nuwara Eliya, Kegalle, Colombo, Matara, Badulla and Monaragala districts. 

Predictions

14-day prediction:
NOAA NCEP Models:

From 24th – 30th Oct: Total rainfall up to 115 mm in Mullaitivu, Vavuniya, Anuradhapura, Mannar and Kurunegala districts; up to 95-105 mm in Puttalam, Matale, Polonnaruwa and Trincomalee districts; up to 85-95 mm in Jaffna, Kilinochchi, Gampaha, Colombo, and Kegalle districts; and up to 75-85 mm in Galle, Ratnapura, Nuwara Eliya and Kandy districts.

From 31st Oct – 6th Nov: Total rainfall up to 125 mm in Anuradhapura and Kurunegala districts; up to 105-115 mm in Mannar, Puttalam, Kurunegala, Anuradhapura, Matale, Gampaha, Colombo, Kalutara Kegalle, Ratnapura and Galle districts; up to 95-105 mm in Vavuniya, Polonnaruwa and Trincomalee; and up to 75-85 mm in Jaffna, Batticaloa, Badulla, Matar and Monaragala districts.

IMD WRF Model Forecast: 

26th Oct: Up to 160 mm of rainfall in Kegalle, Ratnapura, Galle, Matara, Nuwara Eliya and Badulla districts; and up to 80 mm in Vavuniya, Ampara and Hambantota districts; and up to 40 mm in Puttalam, Kurunegala, Gampaha, Colombo and Monaragala districts.

27th Oct: Up to 160 mm in Ratnapura, Matara and Hambantota districts; and up to 40 mm in Batticaloa, Ampara and Galle districts.

IRI Weekly forecast:
From 24 – 29 Oct: Total rainfall up to 200 mm in Kandy, Badulla and Nuwara Eliya districts; up to 150 mm in Mullaitivu, Trincomalee, Anuradhapura, Polonnaruwa, Batticaloa, Matale, Kurunegala, Kegalle, Gampaha, Colombo, Kalutara, Ratnapura and Monaragala districts; up to 100 mm in Jaffna, Kilinochchi, Vavuniya, Puttalam, Galle, Matara and Hambantota districts; and up to 75 mm in rest of the island.

Ocean State (Text Courtesy IRI)
PACIFIC SEAS STATE : October 19, 2018

While ENSO-neutral conditions prevailed in September, signs of El Niño increased in early October 2018 as east-central tropical Pacific SSTs warmed to weak El Niño levels. Also, low level winds showed westerly anomalies in most of the last three weeks. The subsurface water temperature continued to be above-average, and increased further recently. The official CPC/IRI outlook calls for a 70-75% chance of El Niño development during October/November, continuing through winter 2018-19. An El Niño watch is in effect. New forecasts of statistical and dynamical models collectively favor imminent El Niño development, most likely weak to moderate strength, continuing through winter.

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

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