Weekly Hydro-meteorological Report, 4 December, 2014

Highlights

Monitoring and Prediction

Heavy rainfall was observed throughout the country in the previous week with highest rainfall in the northern region. Northern and north-eastern regions received highly above average rainfall during November while below climatological average rainfall was observed in the rest of the country. Rainfall shall decrease during next week in the entire country but not in a significant level. The entire sea region of Sri Lanka shows a neutral sea surface temperature
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Summary

Monitoring


Weekly Monitoring::On 26th and 27th November high rainfall was observed throughout the country averaging up to 60 mm. Highest amount of rainfall observed was in northern and north-eastern regions of the country which reached up to 100 mm. From 28th to 30th of November about 20 mm average rainfall was observed only around the northern and south-east regions in general. Up to 100 mm rainfall was observed in northern and western areas on 1st of December while Central province has received around 30 mm rainfall on 2nd of December. Northern peninsula has received the highest rainfall during the week.


Monthly Monitoring:An average rainfall of 16 mm-18 mm was observed throughout the country with higher precipitation observed in the north-eastern regions of Sri Lanka during November. Highest rainfall during this month was observed in Northern and Eastern provinces. Also the decadal rainfall average was increased from 14 mm to 18 mm within a week.

Predictions

14-day prediction:NOAA NCEP models predict a decrease in rainfall in the next two weeks compared to previous weeks. The entire country shall receive rainfall around 75 mm during 3rd to 9th December. Rainfall shall decrease throughout the country averaging around 35 mm during the week of 10th to 16th of December.

IMD WRF Model Forecast & IRI forecast:According to the IMD WRF model the southern region (around Galle and Matara) of the country shall receive average rainfall up to 35 mm on 05th of December while light rainfall is expected in the Jaffna peninsula on the same day. Rainfall shall increase again on the 6th of December with the area around Batticaloa expected to receive up to 65 mm rain and the rest of the country expected to receive up to 35 mm rainfall.

Seasonal Prediction:As per IRI Multi Model Probability Forecast issued in November for the season December 2014 to February 2015, Rainfall shall remain climatological while the temperature shall be above normal with about 70% probability.

PACIFIC SEAS STATE November 20, 2014 :During late October through early November the SST exceeded thresholds for weak Niño conditions, although only some of the atmospheric variables indicate an El Niño pattern. Most of the ENSO prediction models indicate weak El Niño conditions during the November-January season in progress, continuing well into the northern spring 2015.
INDIAN OCEAN STATE :Sea surface temperature was neutral in the entire region around Sri Lanka.
MJO STATE :MJO is in Phase 5 in Maritime Continent and shall slightly enhance the rainfall in Sri Lanka.