Climate Bulletin For Sri Lanka (15 December 2023)

               

Highlights          

 • High probability of heavy rainfall (> 100 mm) is predicted for Sabaragamuwa, Northern provinces and fairly heavy rainfall is predicted for Central, Uva, North Western provinces during      15 - 21 Dec.

 • During the last week, average daily rainfall over Sri Lanka was 10.4 mm and hydro catchment was 16.5 mm. Extreme rainfall (> 150 mm/day) was in Badulla. The rainfall of last week was twice as normal.

 • From 4  - 10 Dec , up to 4 m/s of south westerly winds were at 850 mb (1.5 km). During 14 - 20 Dec, up to 8 m/s of easterly winds are expected at 850 mb (1.5 km). 

 • Sea surface temperature around Sri Lanka was 0.25 - 1.5ºC above normal. From 7 - 13 Dec, maximum daily temperature was recorded in Moneragala (34.3ºC) and Ratnapura (33.8ºC).

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Predictions

Rainfall

7-day prediction: 
NOAA NCEP models: 

From 15^th December - 21^st December:  

Total rainfall by Provinces

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

MJO based OLR predictions:

For the next 15 days: 

MJO shall moderately suppress the rainfall during 13^th - 22^nd December and slightly suppress the rainfall during 23^rd - 27^th December for Sri Lanka.

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: December 11, 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-December. 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 country in 21^st - 27^th November, 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: Badulla.

Daily Average Rainfall in the Met stations for previous week of (6^th December - 13^th December) = 10.4 mm

Maximum Daily Rainfall: 94.9 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	8.9	30.8	24.7
Eastern hills	8.1	25.5	18.6
Eastern plains	11.6	30.9	24.3
Western hills	11.5	27.7	19.3
Western plains	13.6	31.4	24.4
Southern plains	7.0	31.2	24.4

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	16.5	119.9	0.0

Wind: South westerly winds prevailed in the sea area and around the island last week.

Temperatures: The temperature anomalies were above normal for the country driven by the warm SST’s.

Predictions

Rainfall: During the next week (15^th December - 21^st December), heavy rainfall is predicted for the Sabaragamuwa, Northern provinces and fairly heavy rainfall is predicted for the Central, Uva, North Western provinces and less rainfall is predicted for rest of the country.

Temperatures: The temperature will remain seasonably near normal for the country during 14^th December - 20^th December.

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

MJO shall moderately suppress the rainfall during 13^th - 22^nd December and slightly suppress the rainfall during 23^rd - 27^th December for Sri Lanka.

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