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Friday, July 21, 2023

Climate Bulletin For Sri Lanka (21 July 2023)


Highlights          


 • Fairly heavy rainfall (55 mm) is predicted for the Southern, Sabaragamuwa provinces and less rainfall is predicted for the rest of the country during 20 - 26 July.
 • During the last week, average daily rainfall over Sri Lanka was 1.2 mm and  hydro catchment areas received 3.4 mm. Highest average rainfall of 3.5 mm/day received in Eastern hills.
 • From 11 - 17 Jul, up to 15 m/s of northwest-westerly winds were at 850 mb (1.5 km).
During 21 - 27 Jul, up to 15 m/s of northwest-westerly winds are expected at 850 mb (1.5 km)
 • Sea surface temperature around Sri Lanka was 0.5 - 1.5ºC above normal. Average maximum land temperature ranged from 31 - 32ºC and minimum ranged from 24 - 25ºC with a drop in the hills. 




Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 
From 20th July – 26th July:  
Total rainfall by Provinces
  • 55 - Southern, Sabaragamuwa
  • 45 - Western
  • 35 - Central
  • 25 - Uva
  • ≤ 5 - Northern, North Western, North Central, Eastern
MJO based OLR predictions:
For the next 15 days: 
MJO shall near neutral the rainfall during 20th - 24th July, and slightly suppress the rainfall during 25th July - 3rd August for Sri Lanka.


Ocean State (Text Courtesy IRI)
Pacific Sea Sate: July 17, 2023 
El Nino Mode has set in now according to NOAA since 8th of June. Equatorial sea surface temperatures (SSTs) are above average across the central and eastern Pacific Ocean mid-July. There is a greater than 90% chance that El Niño conditions will continue through the Northern Hemisphere winter.

Indian Sea Sate
Sea surface temperature around Sri Lanka was 0.5ºC above normal to the northern and southern half of the country in 27th June - 3rd July, 2023. A positive Dipole Mode has set in across the Indian Ocean since 8th of June.

 

Interpretation


Monitoring
Rainfall:

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


Daily Average Rainfall in the Met stations for previous week of (12th July – 19th July) = 1.2 mm

Maximum Daily Rainfall: 43.9 mm & Minimum Daily Rainfall: 0.0 mm. 


Region

Average rainfall for last 8 days (mm)

Average temperature for last 8 days (ºC)

Maximum

Minimum

Northern plains

0.1

33.6

26.7

Eastern hills

3.5

29.7

18.7

Eastern plains

0.1

35.5

25.6

Western hills

2.9

27.1

20.5

Western plains

2.1

31.2

26.6

Southern plains

0.4

33.3

25.8













Region

Average rainfall for last 8 days (mm)

Daily maximum rainfall for last 8 days (mm)

Daily minimum rainfall for last 8 days (mm)

Hydro catchment

3.4

43.0

0.0







Wind: Northwest-westerly 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, Western, and Central provinces of the country driven by the warm SST’s.


Predictions
Rainfall: During the next week (20th July - 26th July), fairly heavy rainfall (55 mm) is predicted for the Southern and Sabaragamuwa provinces and less rainfall is predicted for the rest of the country.
Temperatures: The temperature will remain above normal for some parts of the Eastern, Uva, Northern, North Central, and Southern provinces and below normal for some parts of the Central province during 21st - 27th July.
Teleconnections: A positive Dipole Mode has set in across the Indian Ocean since 8th of June. MJO shall near neutral the rainfall during 20th - 24th July, and slightly suppress the rainfall during 25th July - 3rd August for Sri Lanka.
Seasonal Precipitation: The precipitation forecast for the August-September-October, 2023 season shows above normal precipitation for the country.


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