Met Office Weather Warnings

If you have to be out and about this evening and tomorrow, do take care.

Looking out at a lush green lawn – too lush tbh – on this bright sunny morning with a glorious blue sky, punctuated only by fluffy little clouds (cue The Orb), it's hard to believe the Met Office have issued weather warnings.

Storm Ciaran (Kee-ron) set to hit us by about 19.00hrs brings an ever increasing likelihood of heavy rains and strong gusty winds right through the night. Into tomorrow, it's more of the same, with a greater than 90% chance of rain and winds potentially gusting up to about 50 mph at the peak – around lunchtime – easing off towards the end of the afternoon/early evening. Phew.

But what does that mean?

Chance of Rain – or Probability of Precipitation (PoP)

Forecasters use the term "PoP" when attributing a percentage to the chance of rain. It isn't a measure of how heavy the rain will be, it is a measure of how likely it is that somewhere within your selected search area within the given time-frame there is likely to be rain.

The number of raindrops falling from the grey cloud symbol is the measure of how heavy it is.

So a percentage chance of rain forecast somewhere in the vicinity of Curry Rivel doesn't mean you'll get wet – though your neighbours might!

Wind Speed and gusting

Wind speed refers to the average speed over a period of time, while gusts are sudden and rapid increases in strength of wind relative to the wind speed. Gusts are short-lived, usually followed by a lull.

So your weather app will likely show the wind speed and direction – maybe SSW 20 mph – as an average over a given period.

The black circles with arrows – used in most weather forecasts – are the wind gusts, often accompanied by a warning such as gusts of up to 50 mph are possible. Not great for umbrellas.

What about the trees?

Well, there isn't a simple answer. Whilst studies suggest that at a constant wind speed of +90mph almost any tree will uproot or break (speed, not gusts). So much depends on other factors that it isn't really possible to estimate which, if any, trees might be at risk.

Factors include soil conditions, the health of the tree, age, thickness of the trunk, size of the canopy, its situation i.e middle of an open field, side of a mountain, middle of a forest or wood ... ... ...

But I guess we'll all lose a few leaves.

So if you must be out, be careful.