Lake Snow EffectAdded : Tuesday at 16:40 First up, let's take a look at the current temperature chart across Europe at 2 metres :-
We don't need to tell you that's cold as you have probably put your nose outside today and realised that for yourself. One thing which shows up well on the satellite today though is the lake snow effect across the North Sea :-
Lake snow develops when you have freezing air coming off land and moving over warmer seas or lakes. If you take a closer look at the image you'll see that the longer the fetch of water which the air is travelling over, the better organised the showers further on. The showers are also better defined, heavier and more spaced out as they develop into Cumulonimbus clouds and develop outflow which creates the space around them.
For lake snow to occur you need land either side to be at freezing or below and the water in between to be above freezing. The greater the temperature difference, the heavier the showers.
This effect happens around the world, and by looking at the satellite images you can tell a few things. Here is one between Sweden and Finland across the Baltic Sea :-
Note that the clouds are less defined when they reach Sweden. The reason? A short fetch and also the temperature of the Baltic Sea is just above freezing which means less of a temperature difference and hence less convection.
Here is a great example with cold air coming off the ice floes of the Sea of Okhotsk in Eastern Russia towards the North Pacific :-
You can see decent convection thanks to the long fetch and milder waters as the air heads Southeast.
So, snow showers for the East coast, but the intensity, frequency and distribution is down to the distance of the fetch and temperature difference of the air approaching from the East.
METEOROLOGIST : MARSH |