Climate Bulletin For Sri Lanka (20 May 2022)

 

Highlights          

                   

 • Heavy  rainfall above 100 mm is expected  in Sabaragamuwa Western & Southern  provinces during 20th to 24th May.

 • During the last week, average daily rainfall over Sri Lanka was 5.6 mm and hydro catchment areas have received 24.1 mm on average.

 • From 9th - 15th May, up to 15 m/s South-westerlies were experienced over the Island.

 • Sea surface temperature was near-neutral around the Island. Land surface Temperature remained near normal during the last week.

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Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 18^th – 24^th May: 

Total rainfall by Provinces:

• 125 mm - Southern
• 115 mm - Western
• 105 mm - Sabaragamuwa
•  65 mm - Central, North Western
•  55 mm - Uva
•  45 mm - North Central
•  35 mm - Northern, Eastern

From 25^th – 31^st May: 

Total rainfall by Provinces:

• 105 mm - Southern
•  95 mm - Western
•  85 mm - Sabaragamuwa
•  55 mm - Central
•  45 mm - Uva, North Western
•  35 mm - North Central
•  25 mm - Northern, Eastern

MJO based OLR predictions:

For the next 15 days: 

MJO shall slightly suppress the rainfall during 20^th - 22^nd May and moderately enhance the rainfall during 23^rd May – 1^st June.

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: May 11, 2022 

Equatorial sea surface temperatures (SSTs) are below average across most of the Pacific Ocean in mid-May. The tropical Pacific atmosphere is consistent with La Niña. A large majority of the models indicate, though La Niña is favored to continue, the odds for La Niña decrease into the late Northern Hemisphere summer before slightly increasing through the Northern Hemisphere fall and early winter 2022.

Indian Sea Sate

Sea surface temperature was near-neutral around the Island.

Interpretation

Monitoring

Rainfall: 

During the last two weeks, there had been heavy rainfall over the following area: 

Kalutara

Daily Average Rainfall in the Met stations for previous week of (10^th - 17^th May) = 5.6 mm

Rmax: 76 mm & Rmin: 0.0 mm.

Region	Average rainfall for the Last 8 days
Northern Plains	0.6 mm
Eastern	0.6 mm
Western	14.8 mm
Southern Plains	6.5 mm

The Hydro Catchment Areas recorded 24.1 mm of average rainfall for the last week

Rmax: 135 mm & Rmin: 0 mm. 

Wind:

South-westerly prevailed in the sea area surrounding the island last week. 

Temperature: 

The temperature anomalies were near-neutral for the country, driven by the warm SST’s.

Predictions

Rainfall:

During the next week (20^th - 24^th May) heavy rainfall (>100 mm) is predicted for the Southern, Western and Sabaragamuwa provinces.

Temperature:

The temperature remains slightly above normal in the Eastern province during 20^th-28^th May. 

Teleconnections:

La Niña - The SST forecast indicates a continuation of the La Niña event with high probability during May-Jul. And there is some disagreement between the two forecast methods thereafter.

MJO shall slightly suppress the rainfall during 20^th - 22^nd May and moderately enhance the rainfall during 23^rd May – 1^st June.

Seasonal Precipitation: 

The precipitation forecast for the June-July-August season shows below-normal precipitation for the southern province and above-normal precipitation to the north province.