Climate Bulletin For Sri Lanka (8 December 2023)

              

Highlights          

 • High probability of heavy rainfall is predicted for Sabaragamuwa province and fairly heavy rainfall is predicted for Uva, Southern, Central provinces during      7 - 13 Dec.

 • During the last week, average daily rainfall over Sri Lanka was 10.5 mm and hydro catchment was 14.4 mm. Extreme rainfall (> 150 mm/day) was in Galle. The rainfall of last week was twice as normal.

 • From 27 Nov - 3 Dec , up to 5 m/s of north easterly winds were at 850 mb (1.5 km). During 7 - 13 Dec, up to 5 m/s of north easterly winds are expected at 850 mb (1.5 km). 

 • Sea surface temperature around Sri Lanka was 0.25 - 1.5ºC above normal. From 30 Nov - 6 Dec, maximum daily temperature was recorded in Puttalam & Pottuvil (33.7ºC) and  Ratnapura (32.9ºC).

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Predictions

Rainfall

7-day prediction: 
NOAA NCEP models: 

From 7^th December - 13^th December:  

Total rainfall by Provinces

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

MJO based OLR predictions:

For the next 15 days: 

MJO shall slightly enhance the rainfall during 6^th - 10^th December and near normal the rainfall during 11^th - 15^th December and slightly suppress the rainfall during 16^th - 20^th December for Sri Lanka.

Ocean State (Text Courtesy IRI)

Pacific Sea Sate: December 4, 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 early-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 14^th - 20^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: Galle.

Daily Average Rainfall in the Met stations for previous week of (29^th November - 6^th December) = 10.5 mm

Maximum Daily Rainfall: 116.0 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	12.7	30.1	24.6
Eastern hills	5.3	25.6	18.9
Eastern plains	9.4	30.4	24.3
Western hills	12.6	26.5	19.7
Western plains	9.8	30.5	24.7
Southern plains	10.6	30.0	24.6

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	14.4	136.5	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 Central, Sabaragamuwa, North Western, Southern and Western provinces of the country driven by the warm SST’s.

Predictions

Rainfall: During the next week (7^th December - 13^th December), heavy rainfall is predicted for the Sabaragamuwa province and fairly heavy rainfall is predicted for the Uva, 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 7^th December - 13^th December.

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

MJO shall slightly enhance the rainfall during 6^th - 10^th December and near normal the rainfall during 11^th - 15^th December and slightly suppress the rainfall during 16^th - 20^th December for Sri Lanka.

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