Sea surface temperature is expected to fall below the La Nina base in January

25-Dec-2024 06:24 PM

The current and upcoming developments in sea surface temperatures (SST) in the Pacific Ocean suggest a complex and shifting weather scenario for the next few months, with implications for both the La Niña and El Niño phenomena. Here's a breakdown of the situation:

1. La Niña vs. El Niño Conditions:

   • La Niña: There is an expectation that SST will fall below the baseline typically associated with La Niña by January 2025, possibly triggering the La Niña cycle. The U.S. Weather Center reports that there is a 72% chance of La Niña conditions developing between December and February, though it is expected to be weak rather than strong. La Niña is characterized by cooler-than-average SSTs in the central and eastern tropical Pacific, which can influence weather patterns globally.
   • El Niño-Southern Oscillation (ENSO) Neutral Conditions: On the other hand, the Australian Bureau of Meteorology (BOM) and international models suggest that the SST will likely remain within the neutral range through April 2025. This neutral phase means that neither El Niño nor La Niña will dominate, but a subtle tendency towards La Niña-like conditions remains possible, especially if the trade winds strengthen, which can help push cooler waters to the surface.

2. Impact on Global Weather Patterns:

   • India Subcontinent: With the potential for La Niña-like conditions, there could be favorable pre-monsoon rains in the Indian subcontinent. La Niña often brings above-average rainfall to India during the pre-monsoon and monsoon seasons.
   • Latin America: Conversely, Latin American countries, particularly in the Southern Cone (Brazil, Argentina, Uruguay, Paraguay, and parts of Mexico), may experience adverse conditions such as drought in some regions due to the altered atmospheric circulation patterns associated with La Niña. Heavy rainfall and floods could affect other parts of the region. The disruption of agricultural activities, particularly the timing of sowing, could exacerbate these impacts.

3. Trade Winds and SSTs:

   • The strengthening of trade winds in recent weeks has been a key indicator pointing towards the likelihood of La Niña conditions. These winds push warm water away from the South American coast, causing colder water to rise in its place. As this process continues, the atmosphere responds by reinforcing the typical La Niña weather patterns.

4. SST in the Pacific:

   • SSTs are currently either near or slightly below the average in most areas of the eastern and central Pacific Ocean, reinforcing the likelihood of La Niña development. The neutral SST conditions in the tropical Pacific are being closely monitored by meteorologists, as they may transition into either La Niña or El Niño conditions, depending on subtle changes in atmospheric and oceanic factors.

Summary:

While the risk of a strong La Niña event is low, there is still a strong possibility of moderate La Niña conditions emerging in the next few months, particularly from December to February. This will lead to significant weather variations, including potential pre-monsoon rains in South Asia and adverse conditions, such as droughts and floods, in parts of Latin America. Meteorological models and observations suggest that the Pacific Ocean's SSTs and atmospheric patterns will remain in a state of transition, with neutral ENSO conditions likely until at least April 2025.