Climate Bulletin For Sri Lanka (13 May 2022)

 

Highlights          

                   

 • NCEP GFS prediction for 11th onwards, the heaviest rainfall in Ratnapura, Galle &Kalutara districts is hazardous. Heavy rainfall above 100mm is expected  in Sabaragamuwa Wester, Southern & Central provinces.

 • During the last week, average daily rainfall over Sri Lanka was 4.4 mm and hydro catchment areas have received 9.4 mm on average.

 • From 2nd - 8th May, up to 10 m/s westerlies and South-westerlies were experienced over the Island.

 • Sea surface temperature was above 0.5℃ to the north and east of Sri Lanka. Land surface Temperature remained near normal during the last week.

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Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 11^th – 17^th May: 

Total rainfall by Provinces:

• >135 mm - Western, Southern, Sabaragamuwa
• 105 mm - Central
•   95 mm - North Western
•   85 mm - Northern, North Central, Uva
•   65 mm - Eastern

From 18^th – 24^th May: 

Total rainfall by Provinces:

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

MJO based OLR predictions:

For the next 15 days: 

MJO shall neutral during 13^th-15^th May, shall moderately suppress the rainfall during 16^th–20^th May and severely suppress during 21^st–25^th May.

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: May 4, 2022 

Equatorial sea surface temperatures (SSTs) are below average across the most of the Pacific Ocean in early-May. The tropical Pacific atmosphere is consistent with La Niña. A large majority of the models indicate La Niña is favored to continue into the Northern Hemisphere summer.

Indian Sea Sate

Sea surface temperature was above 0.5℃ to the North and East of Sri Lanka.

Interpretation

Monitoring

Rainfall: 

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

Ratnapura

Daily Average Rainfall in the Met stations for previous week of (2^nd-9^th May) 

=4.4 mm

Rmax: 105 mm & Rmin: 0.0 mm.

Region	Average rainfall for the Last 8 days
Northern Plains	0.6 mm
Eastern	3.6 mm
Western	8.6 mm
Southern Plains	3.9 mm

The Hydro Catchment Areas recorded 9.4 mm of average rainfall for the last week

Rmax: 98 mm & Rmin: 0 mm. 

Wind:

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

Temperature: 

The temperature anomalies were above normal for the Western, Sabaragamuwa and North-western provinces and neutral for the rest of the country, driven by the warm SST’s.

Predictions

Rainfall:

During the next week (13^th - 17^th May) heavy rainfall (>100 mm) is predicted for the Western, Sabaragamuwa, Southern, and Central provinces. NCEP GFS prediction for 11^th onwards, the heaviest rainfall expected in Ratnapura, Galle & Kalutara districts is hazardous.

Temperature:

The temperature remains slightly below normal in the Central, Uva & Sabaragamuwa provinces and above normal in the Eastern province during 6^th - 14^th May. 

Teleconnections:

La Nina - The SST forecast indicates that La Niña is favored to continue into the Northern Hemisphere summer (June-August 2022).

MJO shall neutral during 13^th-15^th May, shall moderately suppress the rainfall during 16^th–20^th May and severely suppress during 21^st–25^th May.

Seasonal Precipitation: 

The precipitation forecast for the May-June-July season shows below-normal precipitation for the island, but above-normal precipitation for the northern province.