Climate Bulletin For Sri Lanka (17 November 2023)

           

Highlights          

 • High probability of heavy rainfall (100 - 130 mm) is predicted for Sabaragamuwa, Uva, Western provinces and fairly heavy rainfall is predicted for Southern, Central provinces during     16 - 22 Nov.

 • During the last week, average daily rainfall over Sri Lanka was 16.7 mm and hydro catchment was 16.6 mm. Extreme rainfall (≥ 150 mm/day) was in Ampara and Badulla. The rainfall of last week was twice as normal.

 • From 6 - 12 Nov, up to 4 m/s of north easterly winds were at 850 mb (1.5 km). During 16 - 22 Nov, up to 4 m/s of north westerly winds are expected at 850 mb (1.5 km). 

 • Sea surface temperature around Sri Lanka was 0.5 - 1.5ºC above normal. From 8 - 15 Nov, maximum daily temperature was recorded in Ratnapura  (34.1ºC) and Puttalam (33.7ºC).

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Predictions

Rainfall

7-day prediction: 
NOAA NCEP models: 

From 16^th November - 22^nd November:  

Total rainfall by Provinces

• 70 - 130 mm - Sabaragamuwa, Uva, Western
• 40 - 70 mm   - Southern, Central
• 20 - 40 mm   - Eastern, North Central, North Western
• ≤ 20 mm       - Northern

MJO based OLR predictions:

For the next 15 days: 

MJO shall slightly suppress the rainfall during 15^th - 19^th November, slightly enhance the rainfall during 20^th - 24^th November, and moderately enhance the rainfall during 25^th - 29^th November for Sri Lanka.

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: November 13, 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 mid-November. El Niño is anticipated to continue through the Northern Hemisphere spring (with a 62% chance during April-June 2024).

Indian Sea Sate

Sea surface temperature around Sri Lanka was 0.5 ℃ above normal to the Western, Southern, and Northern half of the country in 24^th - 30^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 areas: Ampara, Badulla

Daily Average Rainfall in the Met stations for previous week of (8^th November - 15^th November) = 16.7 mm

Maximum Daily Rainfall: 131.5 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	18.8	29.7	24.2
Eastern hills	10.2	26.0	18.5
Eastern plains	18.3	31.1	24.3
Western hills	13.6	28.1	19.4
Western plains	16.7	31.1	24.4
Southern plains	19.8	30.6	22.7

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	16.6	77.0	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, Central, and Western provinces of the country driven by the warm SST’s.

Predictions

Rainfall: During the next week (16^th November - 22^nd November), heavy rainfall is predicted for the Sabaragamuwa, Uva, and Western provinces and fairly heavy rainfall is predicted for the Southern and Central provinces and less rainfall is predicted for rest of the country.

Temperatures: The temperature will remain seasonably near normal for the country during 16^th November - 22^nd November.

Teleconnections: A positive Dipole Mode has set in across the Indian Ocean since 8^th of June.

MJO shall slightly suppress the rainfall during 15^th - 19^th November, slightly enhance the rainfall during 20^th - 24^th November, and moderately enhance the rainfall during 25^th - 29^th November for Sri Lanka.

Seasonal Precipitation: The precipitation forecast for the December-January-February, 2024 season shows near normal precipitation.