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Weather updates from site founder Brian Gaze that keep you in the know.
Most seasonal computer models are pointing towards the UK having a milder than average winter. In fact some suggest the likelihood of it being very mild! However, it is not a certainty and there could be a number of surprises.
Projections from medium range models are inconsistent at the moment. There isn't a strong signal for a cold weather early in the meteorological winter but there is a suggestion that the Atlantic flow will be disrupted. If we end up with high pressure centred to the southeast a very mild upper level air mass may end up sitting over us for a long period of time.
On the other hand if high pressure become established to the north and west the chances are it will quickly turn cold. Some computer models show this happening. This morning's ECM 00z run is an example but there have been others in recent days. I'd definitely recommend keeping an eye open in the coming days.
In the longer term there is a lot of interest in the possibility of a Sudden Stratospheric Warming (SSW) event. SSWs have been discussed elsewhere on TWO. The key thing to remember is they lead to the westerly flow becoming disrupted with more amplified or meridional patterns developing. That means cold blocks of upper level air are shunted out of the arctic down to mid latitude locations such as the UK. Cold weather isn't a given though. It depends on where the ridges and troughs set-up. In fact last winter the record breaking warmth in February was in part due to a meridional flow with the UK sitting under a warm air mass from the south rather than a cold one originating in the arctic.
The video below shows the GFS 00z 10hPa ( a level in the stratosphere) forecast for the next 16 days. The oranges which appear later in the sequence show the warming.
There has been a lot of talk about the coming winter being mild or very mild. That outcome is very possible. However, other factors suggest the likelihood of surprises. With medium range computer models possibly hinting at colder conditions and the likelihood of an SSW increasing, the chance of it being cold or very cold shouldn't be discounted at this stage. The TWO winter forecast will be issued at the end of November so you'll need to wait until then to see which side of the fence we have landed on.
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