Highlights
• Fairly heavy rainfall is predicted for the Southern and Easter provinces during 23 Feb – 1 Mar. The seasonal forecast shows a higher tendency for above-normal precipitation for southern half of the country from March - May, 2023.
• During the last week, maximum daily rainfall over Sri Lanka was 237 mm in Ampara and hydro catchment areas received 3.7 mm on average. Highest average rainfall 9.1 mm/day received to Eastern plains of the country.
• From 14 - 20 Feb, up to 6 m/s of north easterly winds were experienced at 850 mb level over the island. During 24 Feb- 2 Mar north easterly winds are expected for the country.
• Sea surface temperature around Sri Lanka was below normal for northern half of the island. Land surface temperature remained near normal.
Predictions
Rainfall
14-day prediction:NOAA NCEP models:
From 23rd February – 1st March:
Total rainfall by Provinces:
- 55 mm - Southern, Eastern
- 35 mm - Northern, North Central, Sabaragamuwa
- 25 mm - Western, Uva
- ≤ 15 mm - Central, North Western
From 2nd March – 8th March:
Total rainfall by Provinces:
- 65 mm - Southern, Eastern
- 45 mm - Sabaragamuwa, Northern
- 35 mm - North Central, Western, Uva
- ≤ 25 mm - North Western, Central
MJO based OLR predictions:
For the next 15 days:
MJO shall moderately suppress the rainfall during 23th February – 4th March, and significantly suppress the rainfall during 5th March – 9th March for Sri Lanka.
Ocean State (Text Courtesy IRI)
Pacific Sea Sate: February 20, 2023
Equatorial sea surface temperatures (SSTs) are below average across most of the Pacific Ocean mid - February. The tropical Pacific atmosphere is consistent with La Niña. A large majority of the models indicate ENSO-neutral conditions will begin within the next couple of months, and persist through the Northern Hemisphere spring and early summer.
Indian Sea Sate
Sea surface temperature around Sri Lanka was below - 0.5℃ to the northern half of the country in 1st February, 2023. Across the Indian Ocean, a classical negative Indian Ocean Dipole prevails as is typical during a La Niña.
Interpretation
Monitoring
Rainfall:
During the last two weeks, there had been very heavy rainfall over the following area:
Ampara
Daily Average Rainfall in the Met stations for previous week of (14th February – 21st February) = 4.5 mm
Rmax: 107.2 mm & Rmin: 0.0 mm.
Region | Average rainfall for the Last 8 days |
Northern Plains | 0.4 mm |
Eastern | 9.1 mm |
Western | 4.9 mm |
Southern Plains | 0.9 mm |
The Hydro Catchment Areas recorded 3.7 mm of average rainfall for the last week
Rmax: 55.8 mm & Rmin: 0.0 mm.
Wind:
North easterly winds prevailed in the sea area and around the island last week.
Temperature:
The temperature anomalies were below normal for the Northern half of the island and above normal for the Sabaragamuwa province, driven by the warm SST’s.
Predictions
Rainfall:
During the next week (23rd February – 1st March), Fairly heavy rainfall (55 mm) is predicted for the Southern and Eastern provinces, and less rainfall is expected for rest of the country.
Temperature:
The temperature will remain above normal for some parts of the Sabaragamuwa, North western, North central and Uva provinces and below normal for Nuwara Eliya district during 25th February – 5th March.
Teleconnections:
ENSO-neutral conditions will begin within the next couple of months, and persist through the Northern Hemisphere spring and early summer.
MJO shall moderately suppress the rainfall during 23th February – 4th March, and significantly suppress the rainfall during 5th March – 9th March for Sri Lanka.
Seasonal Precipitation:
The precipitation forecast for the March-April-May 2023 season shows a higher tendency of above-normal precipitation for southern half of the country.
