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Friday, May 27, 2022

Climate Bulletin For Sri Lanka (27 May 2022)


Highlights          

                   

 • Heavy  rainfall above 100 mm is expected  in Sabaragamuwa, Western and Southern  provinces during 25th - 31st May.
 • During the last week, the average daily rainfall over Sri Lanka was 4.5 mm and hydro catchment areas have received 11.1 mm on average.
 • From 16th - 22nd May, up to 20 m/s of south-westerlies were experienced over the island.
 • Sea surface temperature was observed to be below average of 0.5°C around the island. Land surface temperature remained near normal during the last week.




Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 
From 25th – 31st May
Total rainfall by Provinces:
  • 115 mm - Western, Southern
  • 105 mm - Sabaragamuwa
  •  55 mm - North Western, Central
  •  45 mm - Uva
  •  25 mm - North Central, Eastern
  •  15 mm - Northern
From 1st – 7th June
Total rainfall by Provinces:
  • 135 mm - Southern, Western
  • 115 mm - Sabaragamuwa
  •  65 mm - Central, North Western, Uva
  •  35 mm - North Central, Eastern 
  •  25 mm - Northern
MJO based OLR predictions:
For the next 15 days: 
MJO shall neutral during 25th - 29th May; shall moderately suppress the rainfall during 30th May – 3rd June and significantly suppress the rainfall during 4th – 8th June.

Ocean State (Text Courtesy IRI)
Pacific Sea Sate: May 18, 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 observed to be below average of 0.5°C around the island.

Interpretation


Monitoring
Rainfall: 
During the last two weeks, there had been very heavy rainfall over the following area: Colombo
Daily Average Rainfall in the Met stations for previous week of (17th - 24th May) = 4.5 mm
Rmax: 105.7 mm & Rmin: 0.0 mm.

Region

Average rainfall for the Last 8 days

Northern Plains

3.4 mm

Eastern

0.05 mm

Western

9.0 mm

Southern Plains

1.6 mm


The Hydro Catchment Areas recorded 11.1 mm of average rainfall for the last week.
Rmax: 108 mm & Rmin: 0 mm. 

Wind:
South-westerly prevailed in the sea area surrounding the island last week. 
Temperature: 
The temperature anomalies were slightly below normal for the north central province, driven by the warm SST’s.

Predictions
Rainfall:
During the next week (27th - 31st May) heavy rainfall (>100 mm) is predicted for the Southern, Western and Sabaragamuwa provinces.
Temperature:
The temperature remains slightly above normal in the Northern and Eastern provinces and slightly below normal in the central province during 27thMay - 4th June
Teleconnections:
La Niña - Though La Niña is favored to continue, the odds for La Niña decrease into the late Northern Hemisphere summer (August-October 2022).
MJO shall neutral during 25th - 29th May; shall moderately suppress the rainfall during 30th May – 3rd June and significantly suppress the rainfall during 4th – 8th 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.

Friday, May 20, 2022

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.




Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 
From 18th – 24th 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 25th – 31st 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 20th - 22nd May and moderately enhance the rainfall during 23rd May – 1st 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 (10th - 17th 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 (20th - 24th 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 20th-28th 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 20th - 22nd May and moderately enhance the rainfall during 23rd May – 1st 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.

Friday, May 13, 2022

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.




Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 
From 11th – 17th 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 18th – 24th 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 13th-15th May, shall moderately suppress the rainfall during 16th–20th May and severely suppress during 21st–25th 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 (2nd-9th 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 (13th - 17th May) heavy rainfall (>100 mm) is predicted for the Western, Sabaragamuwa, Southern, and Central provinces. NCEP GFS prediction for 11th 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 6th - 14th 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 13th-15th May, shall moderately suppress the rainfall during 16th–20th May and severely suppress during 21st–25th 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.