Weekly Hydro-meteorological Report, 22, June 2017

Highlights:

•   The WRF model predicts up to 36 mm of rainfall in Western regions of the country on 23rd and 24th of June.  
•   Between 14-20 Jun: Rainfall up to 80 mm was recorded in Galle district on the 14th.
•   From 4-10 Jun: minimum temperature of 15 ^OC was recorded from Nuwara Eliya district while northern and eastern coastal regions of the island recorded a maximum temperature between 30-35 ^OC.
•   From 11-17 Jun: up to 54 km/h, northwesterly winds were experienced by the whole island.
•   Average sea surface temperature was observed in the seas around Sri Lanka.

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Summary

Monitoring

Weekly Monitoring: On June 14th, Galle district received up to 80 mm of rainfall; Matara district up to 50 mm; Ratapura and Kalutara districts up to 20 mm; and most southwestern regions of the island up to 10 mm. On the 15th several regions of Ratnapura, Matara, Hambantota, Ampara, Badulla and Monaragala districts received up to 10 mm of rainfall. On the 16th Ampara and Monaragala districts received up to 30 mm of rainfall; and Kaluara, Ratnapura, Batticaloa and Badulla districts up to 20 mm. On the 17th northern regions of Badulla district received up to 30 mm of rainfall; and Kandy district up to 20 mm. On the 18th Ampara and Monaragala districts received up to 30 mm of rainfall; Badulla. Kandy and Nuwara Eliya districts up to 20 mm; and Kegalla and Gampaha districts up to 10 mm. On the 19th Ampara district received up to 70 mm of rainfall; Batticaloa district up to 50 mm; Monaragala district up to 30 mm and Badulla district up to 20 mm. No significant rainfalls were recorded on the 20th.

Total Rainfall for past week :  The RFE 2.0 tool shows total rainfall of 50-75 mm in Galle, Ampara, Badulla and Monaragala districts; up to 25-50 mm in Batticaloa, Ratnapura and Matara districts. It shows below average rainfall up to 50 mm Ampara, Badulla, Monaragala and Galle districts; and below average rainfall up to 10-25 mm in many western and northern parts of the island.

Monthly Monitoring: During May - above average rainfall conditions were experienced in the entire island except for Batticaloa, Ampara and Jaffna districts. Ratnapura district received up to 450 mm above average rainfall; and Kegalla, Kalutara, Matara and Galle districts received up to 360 mm; Nuwara Eliya district up to 240 mm and many parts of the island up to 120 mm. Monthly total rainfall for Ratnapura, Kalutara and Galle districts amounted to 540 mm; up to 420 mm for Kegalla district; and 360 mm for Nuwara Eliya, Colombo and Gampaha districts. The CPC Unified Precipitation Analysis tool shows ~1000 mm of total rainfall in Ratnapura district; up to ~750 mm in Kegalla, Colombo, Kalutara and Galle districts; and up to ~500 mm Kurunegala, Gampaha, Nuwara Eliya and Matara districts; up to 300 mm in Puttalam, Kandy, Badulla, Monaragala and Hambantota districts; and up to 200 mm in Anuradhapura, Polonnaruwa and Matale districts.

Predictions

14-day prediction:
NOAA NCEP Models:
From 21st-27th Jun: Total rainfall between 115-125 mm Ratnapura district; up to 95-105 mm in Colombo, Kegalla, Kandy, Nuwara Eliya and Galle districts; up to 45-55 mm in Gampaha, Matale, Kandy, Nuwara Eliya and Matara districts; up to 35-45 mm in Puttalam and Kurunegala districts.
From 28th Jun-4 Jul: Total rainfall between 95-105 mm in Kegalla, Gampaha and Ratnapura districts; and up to 45-55 mm in Puttalam, Kurunegala, Kandy, Nuwara Eliya and Galle districts.

IMD WRF Model Forecast & IRI forecast:
23th Jun: Up to 36 mm of rainfall in Puttalam, Kurunegala, Gampaha, Colombo, Kalutara, Galle, Ratnapura and Kegalla districts; and up to 8 mm in Mannar, Vavuniya, Anuradhapura, Matale, Kandy, Nuwara Eliya, Ampara, Monaragala and Matara.
24th Jun: Up to 36 mm of rainfall in Puttalam, Kurunegala, Gampaha, Colombo, Kalutara, Galle, Ratnapura and Kegalla districts; and up to 8 mm in Mannar, Vavuniya, Anuradhapura, Matale, Kandy, Nuwara Eliya, Ampara and Matara.

Seasonal Prediction:  Apr to Jun: the total 3-month precipitation shall be climatological for the whole country. The 3-month temperature has more than 70-80% likelihood in the whole of the island of being in the above-normal tercile.

Ocean State (Text Courtesy IRI)
PACIFIC SEAS STATE : June 15, 2017
In mid-June 2017, the tropical Pacific remained in an ENSO-neutral state, with SSTs not far from the El Niño threshold in the east-central tropical Pacific but the atmosphere maintaining ENSO-neutral patterns. The collection of latest ENSO prediction models indicates ENSO-neutral as the most likely condition during summer, with chances for El Niño development rising to about 40-45% during fall and early winter.

INDIAN OCEAN STATE : Average sea surface temperature was observed in the seas around Sri Lanka.

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