Thunderstorms and Friction...Added : Thursday at 10:25 Turning pretty warm over the next 24 hours across much of the UK as a plume of warmer air comes in from the South with temperatures up into the low 30's across the Southeast corner.
Now, usually, with these scenarios where you have a plume extending from the South and then cooler air coming in from the West we tend to start talking about thunderstorms developing, but this time we've been a little quiet about it. You might think we haven't noticed the plume (but we have). You might think we have no idea what will happen (but we do) or you may think we are still being distracted by that Amazon delivery which tells us it will be here sometime today before 9pm (which it might).
But, it's none of those.
If you look at the GFS ► for tomorrow then you can see the plume across the UK :-
Nothing strange about that. Now look at where the cold front is for the system :-
Yup, the surface and upper level cold front are both aligned vertically out across Ireland. This is important. Plumes which develop into thunderstorms tend to be tilted with height. The cooler air comes in aloft at around 35,000ft from the West as the winds change and this progressively lowers as the cold front approaches. This process effectively erodes the CAP and the hot temperatures near the surface have more of a chance of break through and rising which creates the thunderstorms ahead of the front.
But tomorrow, the cold front is very well vertically stacked which delays this process. As the front moves East across the UK, so the cooler air near the surface is slowed down a little by friction. This then allows the cold front to start tilting a little more and the risk of thunderstorms increases, but different models show different speeds of this happening.
The GFS ► shows this happening once the front clears the East coast :-
FMI on the other hand has this a little quicker and as a result we see a plume develop with thunderstorms across Central areas :-
So, as you can see, it's not quite as clear cut as we might expect or hope for. We will continue to see if the models come to some consensus through the course of today, it's possible the end result will sit in the middle with thunderstorms across Eastern areas.
But, we just wanted to let you know as to why meteorologists are holding back on the advisories for thunderstorms for this system more than usual.
Now, where is that Amazon parcel? Still at the depot... great!
METEOROLOGIST : YOURPARCELWILLBEWITHYOUSOON |