Weekly Hydro-meteorological Report, 28 May, 2015

Highlights:


During 20th – 26th May 2015, only slight amounts of rainfall was observed throughout the country. Rainfall was only observed in the south western region during this period. However NOAA models predict high rainfall in the north western region of the country in the next fortnight while rainfall in the south western region is expected in the next few days. The MJO has been weak for some time now and therefore no influence on the rainfall from MJO is expected.
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Summary

Monitoring


Weekly Monitoring:During the time period 20th May – 26th May 2015, a significant amount of rainfall was not observed in any part of the country. Only light rainfall was observed in south western region of the country.


Monthly Monitoring: In April 2015 the entire country received above average rainfall except in Trincomalee, Batticaloa, Jaffna and Polonnaruwa districts and the northern regions of Ampara district.

Predictions

14-day prediction: NOAA NCEP models predict high rainfall in the north western region of the country in the next two weeks. Up to 65 mm total rainfall is expected in this region during this period.

IMD WRF Model Forecast & IRI forecast: According to the IMD WRF model south western region of the country shall receive rainfall up to 35 mm and the rest of the country shall not receive any rainfall on 29th and 30th May. NOAA CFS models also predict some rainfall (up to 50 mm total) in the south western region during 27th May- 1st June 2015.

Seasonal Prediction:As per IRI Multi Model Probability Forecast for June to August, the total 3 month precipitation shall be climatological. The 3 month temperature has more than 70-80% likelihood in the entire country of being in the above-normal tercile during this period.

PACIFIC SEAS STATE May 21, 2014 :During late April through mid-May 2015 the SST was at a weak to moderate Niño level. The atmospheric variables also indicate an El Niño pattern, including weakened trade winds, low Southern Oscillation Index and excess rainfall in the central tropical Pacific. The consensus of ENSO prediction models indicate weak to moderate El Niño conditions during the May-July 2015 season in progress, likely strengthening during summer and lasting through 2015.
INDIAN OCEAN STATE :0.5 degrees C above average temperature was observed around Sri Lanka
MJO STATE :MJO continues to be weak and therefore shall not have a significant impact on the rainfall in Sri Lanka