Highlights
• Fairly heavy (≥75 mm) rainfall is predicted for the Eastern,
Western, Sabaragamuwa, Uva, Central, and North Central provinces and ≥ 55 mm
rainfall is predicted for the rest of the country during 14th - 20th December.
• During the last week, average daily rainfall
over Sri Lanka was 5.8 mm & hydro catchment areas received 3.0 mm on
average. Due
to the intense impact of cyclonic storm 'Mandous', highest average rainfall
(10.2 mm) was received to the Northern plains of the country .
• From 5th - 11th Dec, up to 10m/s of north westerly winds were experienced by the effect of
cyclonic storm 'Mandous' at 850 mb level over the island. During 15th - 21st Dec, up to 8m/s of north easterly winds are expected to the
country.
• Sea surface temperature around Sri Lanka was
above normal to the western, eastern, and southern half of the country. Land surface temperature remained near
normal.
Predictions
Rainfall
14-day prediction:NOAA NCEP models:
From 14th December – 20th December:
Total rainfall by Provinces:
- 85 mm - Eastern
- 75 mm - Western, Sabaragamuwa, Uva, Central, North Central
- 65 mm - Northern
- 55 mm - North Western, Southern
From 21st December – 27th December:
Total rainfall by Provinces:
- 65 mm - Western
- 55 mm - Sabaragamuwa, Eastern
- 45 mm - Northern, Uva, Central, North Central
- ≤ 35 mm - Southern, North Western
MJO based OLR predictions:
For the next 15 days:
MJO shall near neutral the rainfall during 14th
– 18th December, slightly increase the rainfall during 19th
– 23rd December, and moderately increase the rainfall during 24th
– 28th December for Sri Lanka.
Ocean State (Text Courtesy IRI)
Pacific Sea Sate: December 12, 2022
Equatorial
sea surface temperatures (SSTs) are below average across most of the Pacific
Ocean mid - December. The tropical Pacific atmosphere is consistent with La Niña. A
large majority of the models indicate La Niña is favored to continue into the
winter, with equal chances of La Niña and ENSO-neutral during January-March
2023. In February-April 2023, there is a 71% chance of ENSO-neutral.
Indian Sea Sate
Sea surface temperature around Sri
Lanka was above 0.5℃ to
the western, eastern, and southern half of the country in 30th November,
2022. 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: Jaffna
Daily Average Rainfall in the Met stations for previous week of (6th December – 13th December) = 5.8 mm
Rmax: 145.1 mm & Rmin: 0.0 mm.
Region | Average rainfall for the Last 8 days |
Northern Plains | 10.2 mm |
Eastern | 5.0 mm |
Western | 4.3 mm |
Southern Plains | 1.6 mm |
The Hydro Catchment Areas recorded 3.0 mm of average rainfall for the last week
Rmax: 36.0 mm & Rmin: 0.0 mm.
Wind:
North westerly winds prevailed in the sea area
and around the island last week.
Temperature:
The temperature anomalies
were below normal for Central, North Central provinces and some parts of the
Northern, Eastern, Western, Sabaragamuwa, and North Western provinces, driven by the warm SST’s.
Cyclone: The cyclonic storm 'Mandous' originated as a low pressure
area over the southwest Bay of Bengal (8.2° N 88.2° E) and intensified into the
cyclonic storm (CS) on 7th December. Then it moved
west-northwestwards and developed as a severe cyclonic storm (SCS) on 8th
December, maintaining 85 - 95 kmph peak wind speed for north Tamilnadu and
Puducherry coasts. After making landfall on 10th December, it
weakened into a deep depression (DD) over North Tamil Nadu and adjoining South
Karnataka and North Kerala.
Predictions
Rainfall:
During the next week (14th Dec
– 20th Dec), fairly heavy (≥ 75 mm) rainfall is predicted for the Eastern,
Western, Sabaragamuwa, Uva, Central, and North Central provinces; and ≥ 55 mm rainfall is expected for the rest of the country.
Temperature:
The temperature will remain below normal for some
parts of the Central, and Uva provinces during 15th – 21st
December.
Teleconnections:
La Niña is favored to
continue into the winter, with equal chances of La Niña and ENSO-neutral during
January-March 2023.
MJO shall near neutral the rainfall during
14th – 18th December, slightly increase the rainfall
during 19th – 23rd December, and moderately increase the
rainfall during 24th – 28th December for Sri Lanka.
Seasonal Precipitation:
The precipitation
forecast for the December-January-February 2023 season shows a higher tendency
for near-normal precipitation to the country.
