Climate Bulletin For Sri Lanka (3 November 2023)

         

Highlights          

 • High probability of heavy rainfall (100 - 135 mm) for the entire country during 1 - 7 November. >100 mm of  Heavy rainfall  is predicted during 8 - 14 November.

 • During the last week, average daily rainfall over Sri Lanka was 10.0 mm and hydro catchment was 13.7 mm. The rainfall of last week was twice as normal.

 • From 23 - 29 Oct, up to 3 m/s of north easterly winds were at 850 mb (1.5 km). During 3 - 9 Nov, up to 2 m/s of easterly winds are expected at 850 mb (1.5 km). 

 • Sea surface temperature around Sri Lanka was 0.5 - 1.5ºC above normal. From 25 Oct - 1 Nov, maximum daily temperature was recorded in Kurunegala  (33.5ºC) and Ratnapura  (33.4ºC).

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Predictions

Rainfall

14-day prediction: 
NOAA NCEP models: 

From 1^st November - 7^th November:  

Total rainfall by Provinces

• > 135 mm - Southern, Sabaragamuwa, Western, Uva, Central
•   135 mm - Eastern, North Western
•   125 mm - North Central, Northern

From 8^th November - 14^th November:

Total rainfall by Provinces

• > 135 mm - Southern, Sabaragamuwa, Western, Uva
•   135 mm - Central, Eastern
•   115 mm - North Western, North Central, Northern

MJO based OLR predictions:

For the next 15 days: 

MJO shall slightly enhance the rainfall during 1^st - 5^th November and moderately enhance the rainfall during 6^th - 15^th November for Sri Lanka.

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: October 30, 2023 

El Nino Mode has set in according to NOAA since 8^th of June. Equatorial sea surface temperatures (SSTs) are above average across the central and eastern Pacific Ocean late-October. El Niño is anticipated to continue through the Northern Hemisphere spring (with an 80% chance during March-May 2024).

Indian Sea Sate

Sea surface temperature around Sri Lanka was 0.5 ℃ above normal to the Western, Southern, and Eastern half of the country in 10^th - 16^th October, 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 very heavy rainfall over the following area: Ratnapura

Daily Average Rainfall in the Met stations for previous week of (25^th October - 1^st November) = 10.0 mm

Maximum Daily Rainfall: 92.1 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	6.4	31.6	24.4
Eastern hills	7.7	26.5	17.7
Eastern plains	7.6	31.6	23.9
Western hills	16.2	28.2	18.7
Western plains	18.0	31.5	24.0
Southern plains	3.3	31.3	23.9

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	13.7	82.0	0.0

Wind: North easterly winds prevailed in the sea area and around the island last week.

Temperatures: The temperature anomalies were above normal for some parts of the Sabaragamuwa and Central provinces of the country driven by the warm SST’s.

Predictions

Rainfall: During the next week (1^st November - 7^th November), heavy rainfall (> 135 mm) is predicted for the Southern, Sabaragamuwa, Western, Uva, and Central provinces and ≥ 125 mm rainfall is predicted for the Eastern, North Western, North Central, and Northern provinces.

Temperatures: The temperature will remain seasonably near normal for the country during 3^rd November - 9^th November.

Teleconnections: A positive Dipole Mode has set in across the Indian Ocean since 8^th of June. MJO shall slightly enhance the rainfall during 1^st - 5^th November and moderately enhance the rainfall during 6^th - 15^th November for Sri Lanka.

Seasonal Precipitation: The precipitation forecast for the November-December-January, 2024 season shows a 40 - 45% tendency toward above normal precipitation.