Weekly Hydro-meteorological Report, 23, February 2017

Highlights:

•  The WRF model predicts up to 65 mm of rainfall in Kalutara district and 36 mm of rainfall in Southern region of country on the 24th. 
•  Between 15-21 Feb: highest rainfall of 20 mm was recorded on the 18th in Lunugala region of Badulla distict.
•  From 12-18 Feb: minimum temperature of 15  ^OC was recorded from Nuwara Eliya district while Gampaha, Colombo and Kegalla districts recorded a maximum temperature between 30-35  ^OC.
•  From 14-20 Feb: up to 36 km/h north easterly winds were experienced by the entire island.
•   0.5  ^OC below average sea surface temperature was observed in the northern and western seas of Sri Lanka.

Download Full Report




Summary

Monitoring

Weekly Monitoring: On February 15th Alut Oya region of Polonnaruwa district and Dematawewa of Anuradhapura district recived up to 10 mm of rainfall. No rainfalls were recorded within the island on 16th and 17th. On the 18th Batticaloa, Ampara, Monaragala, Hambantota, Galle, Ratnapura and Kegalla districts recived up to 10 mm of rainfall; Badulla district up to 20 mm; and adjacent south eastern sea up to 120 mm of rainfall. On the 19th adjacent south eastern sea received up to 140 mm of rainfall. On the Monaragala and Hambantota, districts received up to 20 mm of rainfall. No significant rainfalls were recorded on the 21st.

Total Rainfall for past week : The RFE 2.0 tool shows total rainfall up to 25 mm for Hambantota, Monaragala and Badulla districts; up to 10 mm for Galle, Matara, Kegalla, Ratnapura, Polonnaruwa, Batticaloa and Ampara districts. It shows above average rainfall of 10-25 mm for Monaragala and Hambantota districts; and below average rainfall of 10-25 mm for Gampaha, Colombo, Kalutara, Polonnaruwa and Ratnapura districts.

Monthly Monitoring: During January - above average rainfall conditions were experienced in Jaffna, Kilinochchi, Mannar, and several regions of Anuradhapura, Polonnaruwa, Matale, Puttalam, Matara and Hambantota districts. These regions received up to 60 mm above average rainfall. Batticaloa, Ampara and Badulla districts received up to 150 mm below average rainfall; and up to 90 mm below average rainfall in many parts of the island. Monthly average rainfall for Anuradhapura, Polonnaruwa, Batticaloa, Ampara, Ratnapura, Galle, Matara and Hambantota amounted to 150 mm/month; and 90 mm/month for many parts of the island. The CPC Unified Precipitation Analysis tool shows ~100 mm of total rainfall in Mannar, Anuradhapura, Polonnaruwa, Galle, Batticaloa, Ampara, Hambantota, Ratnapura and Matale districts; and up to ~75 mm for many parts of the island.

Predictions

14-day prediction:
NOAA NCEP Models:
From 22nd – 28th Feb: No rainfall.
From 1st – 7th Mar: Total rainfall between 75-85 mm in Vavuniya, Anuradhapura and Trincomalee districts; and between 65-75 mm in Mullaitivu, Mannar, Puttalam, Kegalla, Matale, Kandy, Polonnaruwa, Batticaloa, Badulla, Monaragala and Ampara districts.

IMD WRF Model Forecast & IRI forecast:
 24th Feb: Rainfall up to 65 mm in Kalutara district; up to 36 mm of rainfall in Galle, Matara, Hambantota, Ratnapura and Ampara; up to 8 mm of rainfall in Kegalle, Nuwara Eliya and Badulla Districts; and up to 3 mm rainfall in Colombo, Kandy and Batticaloa districts.
 25th Feb: Rainfall up to 8 mm rainfall in Kandy, Badulla, Kalutara, Galle and Matara districts; and up to 3 rainfall in Kurunegala, Puttalam, Kegalla, Nuwara Eliya, Ampara, Ratnapura, Monaragala and Hambantota districts.

Seasonal Prediction: March to May: the total 3-month precipitation shall be climatological for the whole island. The 3-month temperature has more than 70-80% likelihood in the southern region and 60-70% likelihood in the northern region of being in the above-normal tercile.

Ocean State (Text Courtesy IRI)
PACIFIC SEAS STATE : February 16, 2017
During mid-February 2017, the tropical Pacific SST anomaly was close to 0.0C, in the ENSO-neutral range. Although most of the atmospheric variables across the tropical Pacific are now approximately ENSO-neutral, one or two still show a weak La Niña pattern. In particular, the pattern of cloudiness and rainfall in the central and western tropical Pacific remains indicative of a weak La Niña condition. The collection of ENSO prediction models indicates SSTs are likely to remain neutral through May 2017, with a chance for El Niño development later in the year.

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

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