Ex-Hurricane Bertha threatens rain, gales and disruption this weekend
As I wrote a few days ago, the remnants of Hurricane Bertha are heading our way this weekend, bringing the potential for unseasonably heavy rain and strong winds.
So far this summer, the weather has been consistently good for most of us with sunshine and warmth, but Sunday will see a deepening area of low pressure move across the UK.
Even though three days have passed since my blog on Monday, the weather computer models are still struggling to resolve the detail for the track of the low pressure – something that will have a huge influence on which places see the worst of the weather.
Some weather computer models take the low pressure on a more southerly track into northern France, which would take the strongest winds and heavy rain there.
However, others take the low pressure north eastwards across England and Wales, which would bring heavy rain and gales for us.
Why is there still so much uncertainty?
Weather computer models don’t tend to handle the remnants of former hurricanes or tropical storms very well when they arrive at our latitude.
It’s often because of the huge amount of moisture and potential energy that they contain, with the interaction with the jet stream playing a crucial role.
If engaged by the jet stream, the hurricane remnants can spawn deep areas of low pressure bringing gales and heavy rain.
On the other hand, if the jet stream doesn’t engage with this moisture and potential energy, then low pressure is less likely to form and the end result can be very different.
So effectively, different weather computer models are handling this interaction with the jet stream slightly differently, producing a range of possible outcomes.
Possible impacts
Whilst the level of impact from the low pressure system is dependent on the path it takes, the potential for disruption is certainly there.
The latest warning from the Met Office lists a number of potential hazards that could be experienced in the worst affected areas on Sunday.
In terms of rainfall, some places could see as much as 50mm of rain in the space of 24 hours, which would have the potential to cause flash flooding.
One of the more potentially dangerous elements will be the strength of the wind. Around the southern side of the low pressure, winds could gust to around 60mph for coastal areas and 35-45mph inland.
The point to highlight here is that trees are in full leaf and their leaves offer a greater surface area, acting as sails, increasing the risk of branches being blown off or even some trees being blown over.
Along coastal areas, large waves will be an additional concern as the wind whips up the water and pushes it towards the coastline.
Even though there is still some uncertainty in the forecast, it is worth factoring in the potentially severe weather into your plans and keeping a close eye on the forecast this weekend.
As the latest information becomes available, I’ll be posting updates throughout the weekend on Twitter – @liamdutton
You can get the latest flood warnings information for England and Wales on the Channel 4 News live flood warnings map.