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Friday, December 30, 2022

Climate Bulletin For Sri Lanka (30 December 2022)

           

Highlights          


 • Moderately heavy rainfall is predicted for Eastern province and less rainfall is predicted for rest of the country during 29th December - 4th January. Seasonal forecast shows higher tendency for above normal precipitation to the country for  January - March, 2023.
 • During the last week, maximum daily rainfall over Sri Lanka was 106.5 mm & hydro catchment areas received 77.5 mm on maximum. Due to storm (98B), floods and landslides were experienced on 25th Dec in the Kandy district & rainfall in Akurana of 121 mm received till 930 AM was among the highest.
 • From 20th - 26th Dec, up to 10m/s of north easterly winds were experienced at 850 mb level over the island. During the last week, strong winds and rough seas were experienced due to storm (98B) over southwest Bay of Bengal.
 • Sea surface temperature around Sri Lanka was near neutral  to the whole country. Land surface temperature remained near normal. 



Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 
From 29th December – 4th January:
Total rainfall by Provinces:   
  • 35 mm - Eastern
  • 25 mm - Western, Sabaragamuwa, North Central, Central
  • ≤ 15mm - North Western, Uva, Southern, Northern
From 5th January – 11th January:
Total rainfall by Provinces:   
  • 75 mm - Eastern
  • 65 mm - North Central, Central, Uva
  • 55 mm - Western, Sabaragamuwa, North Western, Northern
  • 45 mm - Southern
MJO based OLR predictions:
For the next 15 days: 
MJO shall moderately suppress the rainfall during 29th December – 2nd January, slightly suppress the rainfall during 3rd – 7th January, and near neutral the rainfall during 8th – 12th January for Sri Lanka.

Ocean State (Text Courtesy IRI)
Pacific Sea Sate: December 27, 2022 
Equatorial sea surface temperatures (SSTs) are below average across most of the Pacific Ocean late - December. The tropical Pacific atmosphere is consistent with La Niña. A large majority of the models indicate La Niña is favored to continue into the winter, with equal chances of La Niña and ENSO-neutral during January-March 2023. In February-April 2023, there is a 71% chance of ENSO-neutral.

Indian Sea Sate
Sea surface temperature around Sri Lanka was near neutral to the whole country in 21st December, 2022. Across the Indian Ocean, a classical negative Indian Ocean Dipole prevails as is typical during a La Niña.

 

Interpretation


Monitoring
Rainfall: 
During the last two weeks, there had been heavy rainfall over the following areas: Batticaloa, Kegalle, Puttalam

Daily Average Rainfall in the Met stations for previous week of (21st December – 28th December) = 10.1 mm

Rmax: 106.5 mm & Rmin: 0.0 mm.


Region

Average rainfall for the Last 8 days

Northern Plains

10.5 mm

Eastern

10.2 mm

Western

13.3 mm

Southern Plains

3.2 mm

The Hydro Catchment Areas recorded 12.3 mm of average rainfall for the last week

Rmax: 77.5 mm & Rmin: 0.0 mm.

Wind:
North easterly winds prevailed in the sea area and around the island last week.
Temperature: 
The temperature anomalies were above normal for some parts of the Sabaragamuwa province, driven by the warm SST’s.
Storm: 
The storm '98B' originated as a low pressure area over the southwest Bay of Bengal and intensified into the depression (D) on 22nd December. Then it moved west-southwestwards and centered at Southwest Bay of Bengal close to east coast of Sri Lanka. Then it cut across the island on 25th December, causing heavy rainfall over Eastern, Central, and Western provinces of Sri Lanka. 


Predictions
Rainfall:
During the next week (29th Dec – 4th Jan), moderately heavy rainfall is predicted for the Eastern province; and less rainfall is expected for the rest of the country.
Temperature:
The temperature will remain below normal for some parts of the Central, and Uva provinces during 30th December – 5th January.
Teleconnections:
La Niña is favored to continue into the winter, with equal chances of La Niña and ENSO-neutral during January-March 2023.
MJO shall moderately suppress the rainfall during 29th December – 2nd January, slightly suppress the rainfall during 3rd – 7th January, and near neutral the rainfall during 8th – 12th January for Sri Lanka.

Seasonal Precipitation: 
The precipitation forecast for the January-February-March 2023 season shows a higher tendency for above-normal precipitation to the country.

Friday, December 23, 2022

Climate Bulletin For Sri Lanka (23 December 2022)

          

Highlights          


 • Due to the low pressure area over southwest Bay of Bengal, fairly heavy rainfall is predicted for the Eastern, Sabaragamuwa and Western provinces during 22nd - 28th DecemberSeasonal forecast shows higher tendency for above normal precipitation to the country for  January - March, 2023.
 • During the last week, maximum daily rainfall over Sri Lanka was 106.6 mm & hydro catchment areas received 83.0 mm on maximum and the highest average rainfall (10.1 mm) was received Eastern plains of the country.
 • From 13th - 19th Dec, up to 8m/s of north easterly winds were experienced at 850 mb level over the island. Strong winds and rough seas are expected for following days due to the effect of low pressure area in vicinity of the country
 • Sea surface temperature around Sri Lanka was above normal to the western, eastern, and southern half of the country. Land surface temperature remained near normal



Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 
From 22nd December – 28th December:
Total rainfall by Provinces:   
  • 55 mm - Eastern, Western, Sabaragamuwa
  • 45 mm - Northern, Central, Southern, North Western, North Central, Uva
From 29th December – 4th January:
Total rainfall by Provinces:   
  • 35 mm - Eastern
  • 25 mm - Western, North Central, Northern
  • ≤ 15 mm - Southern, Sabaragamuwa, Central, North Western, Uva
MJO based OLR predictions:
For the next 15 days: 
MJO shall near neutral the rainfall during 22nd December – 26th December, and moderately suppress the rainfall during 27th December – 5th January for Sri Lanka.

Ocean State (Text Courtesy IRI)
Pacific Sea Sate: December 19, 2022 
Equatorial sea surface temperatures (SSTs) are below average across most of the Pacific Ocean mid - December. The tropical Pacific atmosphere is consistent with La Niña. A large majority of the models indicate La Niña is favored to continue into the winter, with equal chances of La Niña and ENSO-neutral during January-March 2023. In February-April 2023, there is a 71% chance of ENSO-neutral.

Indian Sea Sate
Sea surface temperature around Sri Lanka was above 0.5℃ to the western, eastern, and southern half of the country in 30th November, 2022. Across the Indian Ocean, a classical negative Indian Ocean Dipole prevails as is typical during a La Niña.

 

Interpretation


Monitoring
Rainfall: 
During the last two weeks, there had been very heavy rainfall over the following area: Trincomalee

Daily Average Rainfall in the Met stations for previous week of (13th December – 20th December) =

7.7 mm

Rmax: 106.6 mm & Rmin: 0.0 mm.


Region

Average rainfall for the Last 8 days

Northern Plains

7.5 mm

Eastern

10.1 mm

Western

6.0 mm

Southern Plains

3.8 mm


The Hydro Catchment Areas recorded 8.1 mm of average rainfall for the last week

Rmax: 83.0 mm & Rmin: 0.0 mm.

Wind:
North easterly winds prevailed in the sea area and around the island last week.
Temperature: 
The temperature anomalies were below normal for some parts of the North Western, North Central, and Central provinces, driven by the warm SST’s.


Predictions
Rainfall:
During the next week (22nd Dec – 28th Dec), fairly heavy rainfall is predicted for the Eastern, Western, and Sabaragamuwa provinces; and ≥ 45 mm rainfall is expected for the rest of the country.
Temperature:
The temperature will remain below normal for some parts of the Central, Uva, and Sabaragamuwa provinces during 23rd – 29th December.
Teleconnections:
La Niña is favored to continue into the winter, with equal chances of La Niña and ENSO-neutral during January-March 2023.
MJO shall near neutral the rainfall during 22nd December – 26th December, and moderately suppress the rainfall during 27th December – 5th January for Sri Lanka.

Seasonal Precipitation: 
The precipitation forecast for the January-February-March 2023 season shows a higher tendency for above-normal precipitation to the country.

Friday, December 16, 2022

Climate Bulletin For Sri Lanka (16 December 2022)

         

Highlights          


 • Fairly heavy (75 mm) rainfall is predicted for the Eastern, Western, Sabaragamuwa, Uva, Central, and North Central provinces and ≥ 55 mm rainfall is predicted for the rest of the country during 14th - 20th December.
 • During the last week, average daily rainfall over Sri Lanka was 5.8 mm & hydro catchment areas received 3.0 mm on average. Due to the intense impact of cyclonic storm 'Mandous', highest average rainfall (10.2 mm) was received to the Northern plains of the country .
 • From 5th - 11th Dec, up to 10m/s of north westerly winds were experienced by the effect of cyclonic storm 'Mandous' at 850 mb level over the island. During 15th - 21st Dec, up to 8m/s of north easterly winds are expected to the country.
 • Sea surface temperature around Sri Lanka was above normal to the western, eastern, and southern half of the country. Land surface temperature remained near normal. 



Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 
From 14th December – 20th December:
Total rainfall by Provinces:   
  • 85 mm - Eastern
  • 75 mm - Western, Sabaragamuwa, Uva, Central, North Central
  • 65 mm - Northern
  • 55 mm - North Western, Southern
From 21st December – 27th December:
Total rainfall by Provinces:   
  • 65 mm - Western
  • 55 mm - Sabaragamuwa, Eastern
  • 45 mm - Northern, Uva, Central, North Central
  • ≤ 35 mm - Southern, North Western
MJO based OLR predictions:
For the next 15 days: 
MJO shall near neutral the rainfall during 14th – 18th December, slightly increase the rainfall during 19th – 23rd December, and moderately increase the rainfall during 24th – 28th December for Sri Lanka.

Ocean State (Text Courtesy IRI)
Pacific Sea Sate: December 12, 2022 
Equatorial sea surface temperatures (SSTs) are below average across most of the Pacific Ocean mid - December. The tropical Pacific atmosphere is consistent with La Niña. A large majority of the models indicate La Niña is favored to continue into the winter, with equal chances of La Niña and ENSO-neutral during January-March 2023. In February-April 2023, there is a 71% chance of ENSO-neutral.

Indian Sea Sate
Sea surface temperature around Sri Lanka was above 0.5℃ to the western, eastern, and southern half of the country in 30th November, 2022. Across the Indian Ocean, a classical negative Indian Ocean Dipole prevails as is typical during a La Niña.

 

Interpretation


Monitoring
Rainfall: 
During the last two weeks, there had been very heavy rainfall over the following area: Jaffna

Daily Average Rainfall in the Met stations for previous week of (6th December – 13th December) = 5.8 mm

Rmax: 145.1 mm & Rmin: 0.0 mm.


Region

Average rainfall for the Last 8 days

Northern Plains

10.2 mm

Eastern

5.0 mm

Western

4.3 mm

Southern Plains

1.6 mm


The Hydro Catchment Areas recorded 3.0 mm of average rainfall for the last week

Rmax: 36.0 mm & Rmin: 0.0 mm.

Wind:
North westerly winds prevailed in the sea area and around the island last week.
Temperature: 
The temperature anomalies were below normal for Central, North Central provinces and some parts of the Northern, Eastern, Western, Sabaragamuwa, and North Western provinces, driven by the warm SST’s.
Cyclone: The cyclonic storm 'Mandous' originated as a low pressure area over the southwest Bay of Bengal (8.2° N 88.2° E) and intensified into the cyclonic storm (CS) on 7th December. Then it moved west-northwestwards and developed as a severe cyclonic storm (SCS) on 8th December, maintaining 85 - 95 kmph peak wind speed for north Tamilnadu and Puducherry coasts. After making landfall on 10th December, it weakened into a deep depression (DD) over North Tamil Nadu and adjoining South Karnataka and North Kerala.


Predictions
Rainfall:
During the next week (14th Dec – 20th Dec), fairly heavy (≥ 75 mm) rainfall is predicted for the Eastern, Western, Sabaragamuwa, Uva, Central, and North Central provinces; and ≥ 55 mm rainfall is expected for the rest of the country.
Temperature:
The temperature will remain below normal for some parts of the Central, and Uva provinces during 15th – 21st December.
Teleconnections:
La Niña is favored to continue into the winter, with equal chances of La Niña and ENSO-neutral during January-March 2023.
MJO shall near neutral the rainfall during 14th – 18th December, slightly increase the rainfall during 19th – 23rd December, and moderately increase the rainfall during 24th – 28th December for Sri Lanka.

Seasonal Precipitation: 
The precipitation forecast for the December-January-February 2023 season shows a higher tendency for near-normal precipitation to the country.