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. 

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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 20^th - 24^th July, and slightly suppress the rainfall during 25^th July - 3^rd 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 8^th 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 27^th June - 3^rd July, 2023. A positive Dipole Mode has set in across the Indian Ocean since 8^th 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 (20^th July - 26^th 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 21^st - 27^th July.

Teleconnections: A positive Dipole Mode has set in across the Indian Ocean since 8^th of June. MJO shall near neutral the rainfall during 20^th - 24^th July, and slightly suppress the rainfall during 25^th July - 3^rd August for Sri Lanka.

Seasonal Precipitation: The precipitation forecast for the August-September-October, 2023 season shows above normal precipitation for the country.