Jacob's weather forecasts

 Temperatures represent the average for the coldest day

  The most likely scenario is now significant cold weather dropping from the north, limiting temperatures to around freezing. Under the flow, there's an exceptional risk of little areas of low pressure to appear, bringing snow, as well as the usual risk for a battleground situation later on. Take the ICON 0z for example There's also a notable risk of ice days in London. This risk would only be higher further north

F orecasts of colder winters after an AMOC collapse are reliant on climate model output to simulate the effects on such a complex atmospheric system. One well known example is in "Physics-based early warning signal shows that AMOC is on tipping course", where a climate model produced this figure below. As you can see, the winter climate cools to a ludicrous extent. London gets 15C colder in February, while this temperature drop exceeds 30C in the far north of Scotland. Then, if you factor in global warming, this change in temperature is drastically reduced. For example, in "European Temperature Extremes Under Different AMOC Scenarios in the Community Earth System Model", under 2C of climate change, very little change in January temperatures are left. Under 4C of climate change, all cooling is eradicated. In addition, the theory of a colder Europe becomes even more redundant when you factor in how models overestimate the cooling. A prime example is the Younger Dryas,...

In lots of cases, cold air flooding south in North America may be particularly unsupportive of cold weather, but that doesn't seem to be the case at day 7. Particularly low pressure, bringing cold air will go far south enough to provide enough anticlockwise energy along the eastern coast to bring amplification and pull high pressure north, into the North Atlantic, reloading the mid-Atlantic blocking that would be diminishing otherwise There is uncertainty when it comes to the positioning of the renewed blocking, so therefore uncertainty in the result for us, but it at least creates potential for cold setups