Weekly Hydro-meteorological Report, 18, April 2019

Highlights:

•   The IRI weekly rainfall forecast predicts up to 150 mm of total rainfall in Kandy, Badulla and Nuwara Eliya during 17 – 22 Apr.
•   Between 10 – 15 Apr: up to 50 mm of rainfalls were recorded in several districts on 11th, 12th, 13th and 14th.
•  From 9 – 15 Apr: up to 10 km/h, easterly winds were experienced by the entire island.
•   0.5 ⁰C above average sea surface temperature was observed in the seas around Sri Lanka.

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Summary

Monitoring

Weekly Monitoring: On April 10th, Kurunegala and Anuradhapura districts received up to 20 mm of rainfall. On the 11th, Kurunegala district received up to 50 mm of rainfall; Kandy district up to 30 mm; and Anuradhapura, Polonnaruwa, Matale, Kegalle and Nuwara Eliya districts up to 20 mm. On the 12th, Kegalle, Kandy, Colombo and Galle districts received up to 50 mm of rainfall; Kalutara, Gampaha, Nuwara Eliya, Ratnapura and Hambantota districts up to 30 mm; and Puttalam, Matara and Monaragala districts up to 20 mm. On the 13th, Anuradhapura and Kandy districts received up to 50 mm of rainfall; Kurunegala and Matale districts up to 30 mm; and Vavuniya, Trincomalee, Polonnaruwa, Ampara, Badulla, Nuwara Eliya, Kegalle, Kalutara, Galle and Ratnapura districts up to 20 mm. On the 15th, Kegalle, Colombo, Kalutara, Galle and Matara districts received up to 10 mm of rainfall.

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

Monthly Monitoring: During March – Above average rainfall conditions up to 60 mm were experienced in coastal regions of Galle and Matara districts. Below average rainfall conditions up to 180 mm were experienced by Anuradhapura, Polonnaruwa, Batticaloa, Ampara, Monaragala, Ratnapura, Nuwara Eliya, Badulla, Kandy, Kegalle, Matale, Kurunegala and Puttalam districts; and up to 60 mm in rest of the island. The CPC Unified Precipitation Analysis tool shows up to 100 mm of total rainfall in Gampaha, Ratnapura and Kalutara districts; up to 75 mm in Kegalle, Colombo, Galle and Nuwara Eliya districts; up to 50 mm in Puttalam, Kurunegala Kandy, Matara, Monaragala and Badulla districts; and up to 25 mm in Mannar, Anuradhapura, Matale, Batticaloa, Ampara and Hambantota districts. 

Predictions

14-day prediction:
NOAA NCEP Models:

From 17th – 23rd Apr: Total rainfall up to 35 mm in Gampaha, Colombo, Kegalle, Ratnapura, Galle and Matara districts; and up to 15-25 mm in Puttalam, Kurunegala, Anuradhapura, Polonnaruwa, Matale, Kandy, Nuwara Eliya, Badulla, Monaragala, Hambantota and Ampara districts.

From 24th – 30th Apr: Total rainfall up to 85 mm in Galle and Matara districts; up to 65-75 mm Ratnapura and Hambantota districts; up to 55-65 mm in Colombo, Colombo and Kalutara districts; and up to 45-55 mm in Gampaha, Kegalle, Nuwara Eliya, Badulla and Monaragala districts.

IMD WRF Model Forecast: 

19th Apr: Up to 160 mm of rainfall in Mannar, Puttalam, Kurunegala, Gampaha, Kegalle, Matale, Kandy, Nuwara Eliya and Ratnapura districts; and up to 80 mm in Vavuniya, Anuradhapura, Polonnaruwa, Colombo, Kalutara, Badulla and Monaragala districts.

20th Apr: Up to 160 mm of rainfall in Mannar, Kilinochchi, Anuradhapura districts; up to 80 mm in Vavuniya, Puttalam, Kurunegala, Matale, Kandy, Nuwara Eliya, Kalutara and Ratnapura districts; and up to 40 mm in Gampaha and Colombo districts.

IRI Weekly forecast:
From 17th – 22nd Apr: Total rainfall up to 150 mm is expected in Kandy, Badulla and Nuwara Eliya districts; up to 100 mm in Matale, Ampara, Monaragala and Ratnapura districts; up to 75 mm Polonnaruwa, Kurunegala, Kegalle and Batticaloa districts; and up to 50 mm in Trincomalee, Anuradhapura, Puttalam, Gampaha, Colombo, Kalutara, Galle, Matara and Hambantota districts.

Ocean State (Text Courtesy IRI)
PACIFIC SEAS STATE : April 11, 2018

SSTs in the tropical Pacific maintained a weak El Niño level during March and early April, while subsurface waters continued to be warmer than average. Patterns in the atmosphere also continue to show El Niño conditions. Collective model forecasts show a continuation of at least weak El Niño-level SSTs lasting through 2019. The somewhat more cautious official CPC/IRI outlook, with an El Niño advisory, calls for an approximate 65% chance of El Niño prevailing during Jun-Aug, decreasing to 50-55% for Sep-Nov.

INDIAN OCEAN STATE :   0.5 ⁰C above average sea surface temperature was observed in the seas around Sri Lanka.

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