Jacob's weather forecasts

The impacts of an AMOC collapse on Europe Introduction As the Earth has warmed, one section of the Atlantic Ocean has been cooling. This has been attributed to an ocean current, known as the Atlantic Meridional Overturning Circulation (AMOC) weakening. This ocean current regulates the climate worldwide by transporting waters at different temperatures, but this is expected to continue to weaken with climate change, bringing worrying consequences on the climate. However, a more extreme, but still a very plausible scenario of the current collapsing may occur as early as mid-century, where the climate may rapidly change within a few decades. In this summary, I'll focus on Europe. Source: High-resolution ‘fingerprint’ images reveal a weakening Atlantic Ocean circulation (AMOC) The AMOC brings warmer water from the Gulf of Mexico to Europe, contributing to keeping its climate mild in comparison to areas such as Canada. Under a collapse, a lot of the warmer water is shut off, shown by the...

First, let's look at the main factors at play. Current situation Lack of a clear tropospheric polar vortex Higher pressure over Greenland, but not strong enough to have a big influence aside from weakening the Atlantic storm track High pressure over Scandinavian snow cover, trapping cold air that forces the Atlantic storm track to weaken and shift south as it moves west, into the UK Active Atlantic storm track, albeit weaker on the eastern side as it passes over the UK As a result, you have a weak zonal flow dominating the UK, causing rain, as well as more settled weather between low pressure systems. The lack of jet stream amplification keeps temperatures close to average. Mid-range model output On Monday to Wednesday, pressure over Scandinavia is reduced, strengthening the storm track. It creates wetter and slightly milder conditions On the rest of the week, cold air in Scandinavia and Siberia mixes with the Atlantic storm track. In the north of the UK, there's more influence...

Before I come to any conclusions, let's look at the variables at play Current situation An existing, but disorganized TPV (white circle), driving Atlantic storm track (black line) across the ocean, to the UK Persistent high pressure at the surface over Scandinavian snow cover (red circle), blocking the storm track from eastern Europe, weakening it and driving it south. It keeps cold air nearby Mid-range model output Cold air from Scandinavia may draw east into northeastern England in the short term. Otherwise, the somewhat stormy, average pattern over the rest of the UK continues Beginning next weekend, a weakening of the Atlantic storm track may force the jet stream south, allowing the cold air in Scandinavia to push west, into the UK. However, this sort of pattern is especially precarious and subtle shifts in the pattern could doom the UK back into the Atlantic storm track. As well as this, strong blocking to our west (that could make this pattern a whole lot more likely) seems u...